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I previously applied this change in r13-4565 but reverted it due to
PR108071. That PR was then fixed by r13-4712, but I didn't re-apply this
change then because we weren't making the array static; since r14-1500 for
PR110070 we now make the initializer array static, so let's bring this back.
In situations where the maybe_init_list_as_range optimization isn't viable,
we can build an initializer_list<string> with a loop over a constant array
of string literals.
This is represented using a VEC_INIT_EXPR, which required adjusting a couple
of places that expected the initializer array to have the same type as the
target array and fixing build_vec_init not to undo our efforts.
PR c++/105838
gcc/cp/ChangeLog:
* call.cc (convert_like_internal) [ck_list]: Use
maybe_init_list_as_array.
* constexpr.cc (cxx_eval_vec_init_1): Init might have
a different type.
* tree.cc (build_vec_init_elt): Likewise.
* init.cc (build_vec_init): Handle from_array from a
TARGET_EXPR. Retain TARGET_EXPR of a different type.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/initlist-opt5.C: New test.
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In this other testcase from PR110122, during regeneration of the generic
lambda with V=Bar{}, substitution followed by coerce_template_parms for
A<V>'s template argument naturally yields a copy of V in terms of Bar's
(implicitly) defaulted copy constructor.
This however happens inside a template context so although we introduced
a use of the copy constructor, mark_used didn't actually synthesize it,
which causes subsequent constant evaluation of the template argument to
fail with:
nontype-class59.C: In instantiation of ‘void f() [with Bar V = Bar{Foo()}]’:
nontype-class59.C:22:11: required from here
nontype-class59.C:18:18: error: ‘constexpr Bar::Bar(const Bar&)’ used before its definition
We already make sure to instantiate templated constexpr functions needed
for constant evaluation (as per P0859R0). So this patch fixes this by
making us synthesize defaulted constexpr functions needed for constant
evaluation as well.
PR c++/110122
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_call_expression): Synthesize defaulted
functions needed for constant evaluation.
(instantiate_cx_fn_r): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/nontype-class59.C: New test.
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DR 2543 clarifies that constinit variables should follow the language, and
diagnose non-constant initializers (according to [expr.const]) even if they
can actually initialize the variables statically.
DR 2543
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_outermost_constant_expr): Preserve
TARGET_EXPR flags.
(potential_constant_expression_1): Check TARGET_EXPR_ELIDING_P.
* typeck2.cc (store_init_value): Diagnose constinit sooner.
gcc/testsuite/ChangeLog:
* g++.dg/DRs/dr2543.C: New test.
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The restriction on the "permitted result of a constant expression" to not
refer to an immediate function applies regardless of context. The previous
code tried to only check in cases where we wouldn't get the check in
cp_fold_r, but with the next patch I would need to add another case and it
shouldn't be a problem to always check.
We also shouldn't talk about immediate evaluation when we aren't dealing
with one.
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_outermost_constant_expr): Always check
for address of immediate fn.
(maybe_constant_init_1): Evaluate PTRMEM_CST.
gcc/testsuite/ChangeLog:
* g++.dg/DRs/dr2478.C: Handle -fimplicit-constexpr.
* g++.dg/cpp23/consteval-if12.C: Adjust diagnostics.
* g++.dg/cpp2a/consteval20.C: Likewise.
* g++.dg/cpp2a/consteval24.C: Likewise.
* g++.dg/cpp2a/srcloc20.C: Likewise.
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Here we're incorrectly deeming the templated call a.g() inside b's
initializer as potentially constant, despite g being non-constexpr,
which leads to us needlessly instantiating the initializer ahead of time
and which subsequently triggers a bug in access checking deferral (to be
fixed by the follow-up patch).
This patch fixes this by calling get_fns earlier during CALL_EXPR
potentiality checking so that when we extract a FUNCTION_DECL out of a
templated member function call (whose overall callee is typically a
COMPONENT_REF) we do the usual constexpr-eligibility checking for it.
In passing, I noticed the nearby special handling of the object argument
of a non-static member function call is effectively the same as the
generic argument handling a few lines below. So this patch just gets
rid of this special handling; otherwise we'd have to adapt it to handle
templated versions of such calls.
PR c++/109480
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1) <case CALL_EXPR>:
Reorganize to call get_fns sooner. Remove special handling of
the object argument of a non-static member function call. Remove
dead store to 'fun'.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept59.C: Make e() constexpr so that the
expected "without object" diagnostic isn't replaced by a
"call to non-constexpr function" diagnostic.
* g++.dg/template/non-dependent25.C: New test.
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While looking at the empty base handling for 109678, it occurred to me that
we ought to be able to look for an empty base at a specific offset, not just
in general.
PR c++/109678
gcc/cp/ChangeLog:
* cp-tree.h (lookup_base): Add offset parm.
* constexpr.cc (cxx_fold_indirect_ref_1): Pass it.
* search.cc (struct lookup_base_data_s): Add offset.
(dfs_lookup_base): Handle it.
(lookup_base): Pass it.
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Here, when dealing with a class with a complex subobject structure, we would
try and fail to find the relevant FIELD_DECL for an empty base before giving
up. And we would do this at each level, in a combinatorially problematic
way. Instead, we should check for an empty base first.
PR c++/109678
gcc/cp/ChangeLog:
* constexpr.cc (cxx_fold_indirect_ref_1): Handle empty base first.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/variant1.C: New test.
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We were assuming that the result of evaluation of TARGET_EXPR_INITIAL would
always be the new value of the temporary, but that's not necessarily true
when the initializer is complex (i.e. target_expr_needs_replace). In that
case evaluating the initializer initializes the temporary as a side-effect.
PR c++/109357
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_constant_expression) [TARGET_EXPR]:
Check for complex initializer.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/constexpr-dtor15.C: New test.
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This testcase in this PR (already fixed by r13-6526-ge4692319fd5fc7)
demonstrates that maybe_constant_init can be called on an unevaluated
operand (e.g. from massage_init_elt) so this entry point should also
limit constant evaluation in that case, like maybe_constant_value does.
PR c++/109030
gcc/cp/ChangeLog:
* constexpr.cc (maybe_constant_init_1): For an unevaluated
non-manifestly-constant operand, don't constant evaluate
and instead call fold_to_constant as in maybe_constant_value.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/constexpr-inst2.C: New test.
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We crash here since r10-3661, the store_init_value hunk in particular.
Before, we called cp_fully_fold_init, so e.g.
{.str=VIEW_CONVERT_EXPR<char[8]>("")}
was folded into
{.str=""}
but now we don't fold and keep the VCE around, and it causes trouble in
cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
.str's initializer but since it's wrapped in a VCE, we skip the STRING_CST
check and then crash on the CONSTRUCTOR_NO_CLEARING.
PR c++/107280
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_store_expression): Strip location wrappers.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-lambda28.C: New test.
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When processing a noexcept, constructors aren't elided: build_over_call
has
/* It's unsafe to elide the constructor when handling
a noexcept-expression, it may evaluate to the wrong
value (c++/53025). */
&& (force_elide || cp_noexcept_operand == 0))
so the assert I added recently needs to be relaxed a little bit.
PR c++/109030
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_call_expression): Relax assert.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept77.C: New test.
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Similarly to PR107938, this also started with r11-557, whereby cp_finish_decl
can call check_initializer even in a template for a constexpr initializer.
Here we are rejecting
extern const Q q;
template<int>
constexpr auto p = q(0);
even though q has a constexpr operator(). It's deemed non-const by
decl_maybe_constant_var_p because even though 'q' is const it is not
of integral/enum type.
If fun is not a function pointer, we don't know if we're using it as an
lvalue or rvalue, so with this patch we pass 'any' for want_rval. With
that, p_c_e/VAR_DECL doesn't flat out reject the underlying VAR_DECL.
PR c++/107939
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1) <case CALL_EXPR>: Pass
'any' when recursing on a VAR_DECL and not a pointer to function.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/var-templ74.C: Remove dg-error.
* g++.dg/cpp1y/var-templ77.C: New test.
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The stmtexpr19.C testcase used to be rejected as it has a static
variable in statement expression in constexpr context, but as that
static variable is initialized by constant expression, when P2647R1
was implemented we agreed to make it valid.
Now, as reported, the testcase compiles fine, but doesn't actually link
because the static variable isn't defined anywhere, and with -flto ICEs
because of this problem. This is because we never
varpool_node::finalize_decl those vars, the constant expression in which
the DECL_EXPR is present for the static VAR_DECL is folded (constant
evaluated) into just the address of the VAR_DECL.
Now, similar testcase included below (do we want to include it in the
testsuite too?) works fine, because in
cp_finish_decl -> make_rtl_for_nonlocal_decl
we have since PR70353 fix:
/* We defer emission of local statics until the corresponding
DECL_EXPR is expanded. But with constexpr its function might never
be expanded, so go ahead and tell cgraph about the variable now. */
defer_p = ((DECL_FUNCTION_SCOPE_P (decl)
&& !var_in_maybe_constexpr_fn (decl))
|| DECL_VIRTUAL_P (decl));
and so don't defer them in constexpr/consteval functions. The following
patch calls rest_of_decl_compilation which make_rtl_for_nonlocal_decl didn't
call when encountering DECL_EXPRs of such vars during constant evaluation
if they weren't finalized yet.
2023-03-04 Jakub Jelinek <jakub@redhat.com>
PR c++/108702
* constexpr.cc: Include toplev.h.
(cxx_eval_constant_expression) <case DECL_EXPR>: When seeing a local
static initialized by constant expression outside of a constexpr
function which has been deferred by make_rtl_for_nonlocal_decl,
call rest_of_decl_compilation on it.
* g++.dg/ext/stmtexpr19.C: Use dg-do link rather than dg-do compile.
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According to [basic.start.static]/2 and [expr.const]/2, a variable
with static storage duration initialized with a constant initializer
has constant initialization, and such an initializer is manifestly
constant-evaluated.
For copy initialization, we're already getting this right because in
that case check_initializer would consistently call store_init_value,
which for TREE_STATIC variables calls fold_non_dependent_init with
m_c_e=true.
But for direct (or default) initialization, check_initializer doesn't
always call store_init_value. We instead however always call
maybe_constant_init from expand_default_init[1], albeit with m_c_e=false
which means we don't get the "manifestly constant-evaluated" part right
for non-copy-init.
This patch fixes this by setting m_c_e=true in maybe_constant_init for
static storage duration variables, mainly for benefit of the call
to maybe_constant_init from expand_default_init.
[1]: this maybe_constant_init call isn't reached in the copy-init
case because there init is a CONSTRUCTOR rather than a TREE_LIST,
and so we exit early from expand_default_init, returning an INIT_EXPR.
This INIT_EXPR is ultimately what causes us to consistently hit the
store_init_value code path from check_initializer in the copy-init case.
PR c++/108243
gcc/cp/ChangeLog:
* constexpr.cc (maybe_constant_init_1): Override
manifestly_const_eval to true if is_static.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/is-constant-evaluated14.C: New test.
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Here we're attempting to evaluate a PTRMEM_CST in a class that hasn't
been completed yet, but that doesn't work:
/* We can't lower this until the class is complete. */
if (!COMPLETE_TYPE_P (DECL_CONTEXT (member)))
return cst;
and then this unlowered PTRMEM_CST is used as EXPR in
tree op1 = build_nop (ptrdiff_type_node, expr);
and we crash in a subsequent cp_fold_convert which gets type=ptrdiff_type_node,
expr=PTRMEM_CST and does
else if (TREE_CODE (expr) == PTRMEM_CST
&& same_type_p (TYPE_PTRMEM_CLASS_TYPE (type),
PTRMEM_CST_CLASS (expr)))
where TYPE_PTRMEM_CLASS_TYPE (type) is going to crash since the type
is ptrdiff_type_node. We could just add a TYPE_PTRMEM_P check before
accessing TYPE_PTRMEM_CLASS_TYPE but I think it's nicer to explain why
we couldn't evaluate the expression.
PR c++/107574
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_constant_expression): Emit an error when
a PTRMEM_CST cannot be evaluated.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/ptrmem-cst1.C: New test.
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Here we're mishandling the unevaluated array new-expressions due to a
supposed non-constant array size ever since r12-5253-g4df7f8c79835d569
made us no longer perform constant evaluation of non-manifestly-constant
expressions within unevaluated contexts. This shouldn't make a difference
here since the array sizes are constant literals, except they're expressed
as NON_LVALUE_EXPR location wrappers around INTEGER_CST, wrappers which
used to get stripped as part of constant evaluation and now no longer do.
Moreover it means build_vec_init can't constant fold the MINUS_EXPR
'maxindex' passed from build_new_1 when in an unevaluated context (since
it tries reducing it via maybe_constant_value called with mce_unknown).
This patch fixes these issues by making maybe_constant_value (and
fold_non_dependent_expr) try folding an unevaluated non-manifestly-constant
operand via fold(), as long as it simplifies to a simple constant, rather
than doing no simplification at all. This covers e.g. simple arithmetic
and casts including stripping of location wrappers around INTEGER_CST.
In passing, this patch also fixes maybe_constant_value to avoid constant
evaluating an unevaluated operand when called with mce_false, by adjusting
the early exit test appropriately.
Co-authored-by: Jason Merrill <jason@redhat.com>
PR c++/108219
PR c++/108218
gcc/cp/ChangeLog:
* constexpr.cc (fold_to_constant): Define.
(maybe_constant_value): Move up early exit test for unevaluated
operands. Try reducing an unevaluated operand to a constant via
fold_to_constant.
(fold_non_dependent_expr_template): Add early exit test for
CONSTANT_CLASS_P nodes. Try reducing an unevaluated operand
to a constant via fold_to_constant.
* cp-tree.h (fold_to_constant): Declare.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/new6.C: New test.
* g++.dg/cpp2a/concepts-new1.C: New test.
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The r13-2965-g73d9b0e5947e16 change changed the line touched in this patch
from
return RECUR (tmp, want_rval);
to
return RECUR (DECL_INITIAL (tmp), want_rval);
This is on DECL_EXPR handling code, where tmp can be lots of different
trees and DECL_INITIAL unfortunately also means different things on
different trees.
It is the initializer on VAR_DECL, DECL_ARG_TYPE on PARM_DECLs (though
those are unlikely to have DECL_EXPRs), for FUNCTION_DECLs the body,
..., USING_DECL_DECLS on USING_DECLs and DECL_FRIENDLIST on TYPE_DECLs.
The testcase below ICEs because we have a DECL_EXPR for TYPE_DECL
which has non-NULL DECL_FRIENDLIST and we certainly can't recurse on
the friend list.
The following patch will RECUR on DECL_INITIAL only for VAR_DECLs and
for anything else just return true.
2023-03-01 Jakub Jelinek <jakub@redhat.com>
PR c++/108606
* constexpr.cc (potential_constant_expression_1) <case DECL_EXPR>:
Only recurse on DECL_INITIAL (tmp) if tmp is a VAR_DECL, otherwise
just return true.
* g++.dg/cpp1y/pr108606.C: New test.
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In constexpr-nsdmi3.C, with -fno-elide-constructors, we don't elide
the Y::Y(const Y&) call used to initialize o.c. So store_init_value
-> cxx_constant_init must constexpr-evaluate the call to Y::Y(const Y&)
in cxx_eval_call_expression. It's a trivial function, so we do the
"Shortcut trivial constructor/op=" code and rather than evaluating
the function, we just create an assignment
o.c = *(const struct Y &) (const struct Y *) &(&<PLACEHOLDER_EXPR struct X>)->b
which is a MODIFY_EXPR, so the preeval code in cxx_eval_store_expression
clears .ctor and .object, therefore we can't replace the PLACEHOLDER_EXPR
whereupon we crash at
/* A placeholder without a referent. We can get here when
checking whether NSDMIs are noexcept, or in massage_init_elt;
just say it's non-constant for now. */
gcc_assert (ctx->quiet);
The PLACEHOLDER_EXPR can also be on the LHS as in constexpr-nsdmi10.C.
I don't think we can do much here, but I noticed that the whole
trivial_fn_p (fun) block is only entered when -fno-elide-constructors.
This is true since GCC 9; it wasn't easy to bisect what changes made it
so, but r240845 is probably one of them. -fno-elide-constructors is an
option for experiments only so it's not clear to me why we'd still want
to shortcut trivial constructor/op=. I propose to remove the code and
add a checking assert to make sure we're not getting a trivial_fn_p
unless -fno-elide-constructors.
PR c++/101073
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_call_expression): Replace shortcutting trivial
constructor/op= with a checking assert.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-nsdmi3.C: New test.
* g++.dg/cpp1y/constexpr-nsdmi10.C: New test.
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This patch converts the constexpr machinery's manifestly_const_eval flag
into a tri-state enum to allow us to express wanting to fold
__builtin_is_constant_evaluated to false via speculative constexpr
evaluation. For now, only the maybe_constant_value entry point is
changed to take this enum; the others continue to take bool. The
subsequent patch will teach cp_fold (which uses maybe_constant_value) to
fold the builtin to false when called from cp_fold_function and
cp_fully_fold_init.
gcc/cp/ChangeLog:
* constexpr.cc (constexpr_call::manifestly_const_eval): Give
it type int instead of bool.
(constexpr_ctx::manifestly_const_eval): Give it type mce_value
instead of bool.
(cxx_eval_builtin_function_call): Adjust after making
manifestly_const_eval tri-state.
(cxx_eval_call_expression): Likewise.
(cxx_eval_binary_expression): Likewise.
(cxx_eval_conditional_expression): Likewise.
(cxx_eval_constant_expression): Likewise.
(cxx_eval_outermost_constant_expr): Likewise.
(cxx_constant_value): Likewise.
(cxx_constant_dtor): Likewise.
(maybe_constant_value): Give manifestly_const_eval parameter
type mce_value instead of bool and adjust accordingly.
(fold_non_dependent_expr_template): Adjust call
to cxx_eval_outermost_constant_expr.
(fold_non_dependent_expr): Likewise.
(maybe_constant_init_1): Likewise.
* constraint.cc (satisfy_atom): Adjust call to
maybe_constant_value.
* cp-tree.h (enum class mce_value): Define.
(maybe_constant_value): Adjust manifestly_const_eval parameter
type and default argument.
* decl.cc (compute_array_index_type_loc): Adjust call to
maybe_constant_value.
* pt.cc (convert_nontype_argument): Likewise.
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In this test case, we find ourselves evaluating 't' which is
((const struct carray *) this)->data_[VIEW_CONVERT_EXPR<long int>(index)]
in cxx_eval_array_reference. ctx->object is non-null, a RESULT_DECL, so
we replace it with 't':
new_ctx.object = t; // result_decl replaced
and then we go to cxx_eval_constant_expression to evaluate an
AGGR_INIT_EXPR, where we end up evaluating an INIT_EXPR (which is in the
body of the constructor for seed_or_index):
((struct seed_or_index *) this)->value_ = NON_LVALUE_EXPR <0>
whereupon in cxx_eval_store_expression we go to the probe loop
where the 'this' is evaluated to
ze_set.tables_.first_table_.data_[0]
so the 'object' is ze_set, but that isn't in ctx->global->get_value_ptr
so we fail with a bogus error. ze_set is not there because it comes
from a different constexpr context (it's not in cv_cache either).
The problem started with r12-2304 where I added the new_ctx.object
replacement. That was to prevent a type mismatch: the type of 't'
and ctx.object were different.
It seems clear that we shouldn't have replaced ctx.object here.
The cxx_eval_array_reference I mentioned earlier is called from
cxx_eval_store_expression:
6257 init = cxx_eval_constant_expression (&new_ctx, init, vc_prvalue,
6258 non_constant_p, overflow_p);
which already created a new context, whose .object we should be
using unless, for instance, INIT contained a.b and we're evaluating
the 'a' part, which I think was the case for r12-2304; in that case
ctx.object has to be something different.
It no longer seems necessary to replace new_ctx.object (likely due to
changes in empty class handling).
PR c++/108158
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_array_reference): Don't replace
new_ctx.object.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-108158.C: New test.
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evaluation [PR108607]
While potential_constant_expression_1 handled most of OMP_* codes (by saying that
they aren't potential constant expressions), OMP_SCOPE was missing in that list.
I've also added OMP_SCAN, though that is less important (similarly to OMP_SECTION
it ought to appear solely inside of OMP_{FOR,SIMD} resp. OMP_SECTIONS).
As the testcase shows, it isn't enough, potential_constant_expression_1
can catch only some cases, as soon as one uses switch or ifs where at least
one of the possible paths could be constant expression, we can run into the
same codes during cxx_eval_constant_expression, so this patch handles those
there as well.
2023-02-01 Jakub Jelinek <jakub@redhat.com>
PR c++/108607
* constexpr.cc (cxx_eval_constant_expression): Handle OMP_*
and OACC_* constructs as non-constant.
(potential_constant_expression_1): Handle OMP_SCAN and OMP_SCOPE.
* g++.dg/gomp/pr108607.C: New test.
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cxx_eval_call_expression requests an INSERT even in cases when it
would later decide not to insert. This could break double-hashing
chains. Arrange for it to use NO_INSERT when the insertion would not
be completed.
for gcc/cp/ChangeLog
* constexpr.cc (cxx_eval_call_expression): Do not request an
INSERT that would not be completed.
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Here during ahead of time checking of C{}, we indirectly call get_nsdmi
for C::m from finish_compound_literal, which in turn calls
break_out_target_exprs for C::m's (non-templated) initializer, during
which we build a call to A::~A and check expr_noexcept_p for it (from
build_vec_delete_1). But this is all done with processing_template_decl
set, so the built A::~A call is templated (whose form was recently
changed by r12-6897-gdec8d0e5fa00ceb2) which expr_noexcept_p doesn't
expect, and we crash.
This patch fixes this by clearing processing_template_decl before
the call to break_out_target_exprs from get_nsdmi. And since it more
generally seems we shouldn't be seeing (or producing) non-templated
trees in break_out_target_exprs, this patch also adds an assert to
that effect.
PR c++/108116
gcc/cp/ChangeLog:
* constexpr.cc (maybe_constant_value): Clear
processing_template_decl before calling break_out_target_exprs.
* init.cc (get_nsdmi): Likewise.
* tree.cc (break_out_target_exprs): Assert processing_template_decl
is cleared.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/nsdmi-template24.C: New test.
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We currently declare __builtin_source_location with a const void* return
type instead of the actual type const std::source_location::__impl*, and
later when folding this builtin we obtain the actual type via name lookup.
But the below testcase demonstrates this approach seems to interact
poorly with modules, since we may import an entity that uses
std::source_location::current() in its default argument (or DMI) without
necessarily importing <source_location>, and thus the name lookup for
std::source_location will fail at the call site (when using the default
argument) unless we also import <source_location>.
This patch fixes this by instead initially declaring the builtin with an
auto return type and updating it appropriately upon its first use (in
standard code the first/only use would be in the definition of
std::source_location). Thus when folding calls to this builtin we can
get at its return type through the type of the CALL_EXPR and avoid
needing to do a name lookup.
PR c++/100881
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_builtin_function_call): Adjust calls
to fold_builtin_source_location.
* cp-gimplify.cc (cp_gimplify_expr): Likewise.
(cp_fold): Likewise.
(get_source_location_impl_type): Remove location_t parameter and
adjust accordingly. No longer static.
(fold_builtin_source_location): Take a CALL_EXPR tree instead of a
location and obtain the impl type from its return type.
* cp-tree.h (enum cp_tree_index): Remove CPTI_SOURCE_LOCATION_IMPL
enumerator.
(source_location_impl): Remove.
(fold_builtin_source_location): Adjust parameter type.
(get_source_location_impl_type): Declare.
* decl.cc (cxx_init_decl_processing): Declare
__builtin_source_location with auto return type instead of
const void*.
(require_deduced_type): Update the return type of
__builtin_source_location.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/srcloc3.C: Adjust expected note s/evaluating/using.
* g++.dg/cpp2a/srcloc4.C: Likewise.
* g++.dg/cpp2a/srcloc5.C: Likewise.
* g++.dg/cpp2a/srcloc6.C: Likewise.
* g++.dg/cpp2a/srcloc7.C: Likewise.
* g++.dg/cpp2a/srcloc8.C: Likewise.
* g++.dg/cpp2a/srcloc9.C: Likewise.
* g++.dg/cpp2a/srcloc10.C: Likewise.
* g++.dg/cpp2a/srcloc11.C: Likewise.
* g++.dg/cpp2a/srcloc12.C: Likewise.
* g++.dg/cpp2a/srcloc13.C: Likewise.
* g++.dg/modules/pr100881_a.C: New test.
* g++.dg/modules/pr100881_b.C: New test.
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This patch broke a couple of different patterns; reverting while I work on a
fix.
PR c++/108701
This reverts commit bd0485f20f4794f9787237706a6308473a8e9415.
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The previous patch avoided building an initializer_list<string> at all when
building a vector<string>, but in situations where that isn't possible, we
could still build the initializer_list with a loop over a constant array.
This is represented using a VEC_INIT_EXPR, which required adjusting a couple
of places that expected the initializer array to have the same type as the
target array and fixing build_vec_init not to undo our efforts.
PR c++/105838
gcc/cp/ChangeLog:
* call.cc (convert_like_internal) [ck_list]: Use
maybe_init_list_as_array.
* constexpr.cc (cxx_eval_vec_init_1): Init might have
a different type.
* tree.cc (build_vec_init_elt): Likewise.
* init.cc (build_vec_init): Handle from_array from a
TARGET_EXPR. Retain TARGET_EXPR of a different type.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/initlist-opt2.C: New test.
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In this PR, initializing the array of std::string to pass to the vector
initializer_list constructor gets very confusing to the optimizers as the
number of elements increases, primarily because of all the std::allocator
temporaries passed to all the string constructors. Instead of creating one
for each string, let's share an allocator between all the strings; we can do
this safely because we know that std::allocator is stateless and that string
doesn't care about the object identity of its allocator parameter.
PR c++/105838
gcc/cp/ChangeLog:
* cp-tree.h (is_std_allocator): Declare.
* constexpr.cc (is_std_allocator): Split out from...
(is_std_allocator_allocate): ...here.
* init.cc (find_temps_r): New.
(find_allocator_temp): New.
(build_vec_init): Use it.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/allocator-opt1.C: New test.
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gcc/cp/ChangeLog:
* constexpr.cc (maybe_constant_value): Add default arg comments.
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constexpr functions
The following patch implements this paper.
Per further discussions it is implemented for C++23 only, so isn't
treated as a DR, e.g. because the part of the standard the paper is
changing didn't even exist in C++20.
And we gave up on trying to implement it as a pedwarn rather than
error for C++20 and older, because of implicit constexpr lambdas or
-fimplicit-constexpr reasons.
For C++20 and older, the only change is that passing through
definitions of static or thread_local vars usable in constant expressions
is now accepted in statement expressions if they aren't inside of constexpr
or consteval functions.
2022-11-19 Jakub Jelinek <jakub@redhat.com>
gcc/c-family/
* c-cppbuiltin.cc (c_cpp_builtins): Bump __cpp_constexpr
value from 202207L to 202211L.
gcc/cp/
* constexpr.cc (cxx_eval_constant_expression): Implement C++23
P2647R1 - Permitting static constexpr variables in constexpr functions.
Allow DECL_EXPRs of decl_constant_var_p static or thread_local vars.
(potential_constant_expression_1): Similarly, except use
decl_maybe_constant_var_p instead of decl_constant_var_p if
processing_template_decl.
gcc/testsuite/
* g++.dg/cpp23/constexpr-nonlit17.C: New test.
* g++.dg/cpp23/constexpr-nonlit18.C: New test.
* g++.dg/cpp23/feat-cxx2b.C: Adjust expected __cpp_constexpr
value.
* g++.dg/ext/stmtexpr19.C: Don't expect an error.
* g++.dg/ext/stmtexpr25.C: New test.
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Implement the P1492 versions of contracts, along with extensions that
support the emulation of N4820 and other proposals. This implementation
assigns a concrete semantic (one of: ignore, assume, enforce, or
observe) to each contract attribute depending on its labels and
configuration options.
Co-authored-by: Andrew Sutton <asutton@lock3software.com>
Co-authored-by: Andrew Marmaduke <amarmaduke@lock3software.com>
Co-authored-by: Michael Lopez <mlopez@lock3software.com>
Co-authored-by: Jason Merrill <jason@redhat.com>
gcc/ChangeLog:
* doc/invoke.texi: Document contracts flags.
gcc/c-family/ChangeLog:
* c.opt: Add contracts flags.
* c-cppbuiltin.cc (c_cpp_builtins): Add contracts feature-test
macros.
gcc/cp/ChangeLog:
* cp-tree.h (enum cp_tree_index): Add
CPTI_PSEUDO_CONTRACT_VIOLATION.
(pseudo_contract_violation_type): New macro.
(struct saved_scope): Add x_processing_contract_condition.
(processing_contract_condition): New macro.
(comparing_override_contracts): New variable decl.
(find_contract): New inline.
(set_decl_contracts): New inline.
(get_contract_semantic): New inline.
(set_contract_semantic): New inline.
* constexpr.cc (cxx_eval_assert): Split out from...
(cxx_eval_internal_function): ...here.
(cxx_eval_constant_expression): Use it for contracts.
(potential_constant_expression_1): Handle contracts.
* cp-gimplify.cc (cp_genericize_r): Handle contracts.
* cp-objcp-common.cc (cp_tree_size): Handle contracts.
(cp_common_init_ts): Handle contracts.
(cp_handle_option): Handle contracts.
* decl.cc (duplicate_decls): Handle contracts.
(check_tag_decl): Check for bogus contracts.
(start_decl): Check flag_contracts.
(grokfndecl): Call rebuild_postconditions.
(grokdeclarator): Handle contract attributes.
(start_preparsed_function): Call start_function_contracts.
(finish_function): Call finish_function_contracts.
* decl2.cc (cp_check_const_attributes): Skip contracts.
(comdat_linkage): Handle outlined contracts.
* error.cc (dump_type): Handle null TYPE_IDENTIFIER.
* g++spec.cc (EXPERIMENTAL): New macro.
(lang_specific_driver): Add -lstdc++exp if -fcontracts.
* mangle.cc (write_encoding): Handle outlined contracts.
* module.cc (trees_out::fn_parms_init): Handle outlined contracts.
(trees_in::fn_parms_init): Likewise.
(check_mergeable_decl): Likewise.
(module_state_config::get_dialect): Record -fcontracts.
* parser.h (struct cp_unparsed_functions_entry): Add contracts.
* parser.cc (unparsed_contracts): New macro.
(push_unparsed_function_queues): Adjust.
(contract_attribute_p): New.
(cp_parser_statement): Check contracts.
(cp_parser_decl_specifier_seq): Handle contracts.
(cp_parser_skip_to_closing_square_bracket): Split out...
(cp_parser_skip_up_to_closing_square_bracket): ...this fn.
(cp_parser_class_specifier): Do contract late parsing.
(cp_parser_class_head): Check contracts.
(cp_parser_contract_role): New.
(cp_parser_contract_mode_opt): New.
(find_error, contains_error_p): New.
(cp_parser_contract_attribute_spec): New.
(cp_parser_late_contract_condition): New.
(cp_parser_std_attribute_spec): Handle contracts.
(cp_parser_save_default_args): Also save contracts.
* pt.cc (register_parameter_specializations): No longer static.
(register_local_identity): New.
(check_explicit_specialization): Call remove_contract_attributes.
(tsubst_contract, tsubst_contract_attribute): New.
(tsubst_contract_attributes): New.
(tsubst_attribute): Add comment.
(tsubst_copy): Also allow parm when processing_contract_condition.
(tsubst_expr): Handle contracts.
(regenerate_decl_from_template): Handle contracts.
* search.cc (check_final_overrider): Compare contracts.
* semantics.cc (set_cleanup_locs): Skip POSTCONDITION_STMT.
(finish_non_static_data_member): Check contracts.
(finish_this_expr): Check contracts.
(process_outer_var_ref): Handle contracts.
(finish_id_expression_1): Handle contracts.
(apply_deduced_return_type): Adjust contracts.
* tree.cc (handle_contract_attribute): New.
(get_innermost_component, is_this_expression): New.
(comparing_this_references): New.
(equivalent_member_references): New.
(cp_tree_equal): Check it.
* typeck.cc (check_return_expr): Apply contracts.
* Make-lang.in: Add contracts.o.
* config-lang.in: Add contracts.cc.
* cp-tree.def (ASSERTION_STMT, PRECONDITION_STMT)
(POSTCONDITION_STMT): New.
* contracts.h: New file.
* contracts.cc: New file.
gcc/testsuite/ChangeLog:
* g++.dg/modules/modules.exp: Pass dg-options to link command.
* lib/g++.exp: Add -L for libstdc++exp.a.
* g++.dg/contracts/backtrace_handler/assert_fail.cpp: New test.
* g++.dg/contracts/backtrace_handler/handle_contract_violation.cpp: New test.
* g++.dg/contracts/contracts-access1.C: New test.
* g++.dg/contracts/contracts-assume1.C: New test.
* g++.dg/contracts/contracts-assume2.C: New test.
* g++.dg/contracts/contracts-assume3.C: New test.
* g++.dg/contracts/contracts-assume4.C: New test.
* g++.dg/contracts/contracts-assume5.C: New test.
* g++.dg/contracts/contracts-assume6.C: New test.
* g++.dg/contracts/contracts-comdat1.C: New test.
* g++.dg/contracts/contracts-config1.C: New test.
* g++.dg/contracts/contracts-constexpr1.C: New test.
* g++.dg/contracts/contracts-constexpr2.C: New test.
* g++.dg/contracts/contracts-constexpr3.C: New test.
* g++.dg/contracts/contracts-conversion1.C: New test.
* g++.dg/contracts/contracts-ctor-dtor1.C: New test.
* g++.dg/contracts/contracts-ctor-dtor2.C: New test.
* g++.dg/contracts/contracts-cv1.C: New test.
* g++.dg/contracts/contracts-deduced1.C: New test.
* g++.dg/contracts/contracts-deduced2.C: New test.
* g++.dg/contracts/contracts-friend1.C: New test.
* g++.dg/contracts/contracts-ft1.C: New test.
* g++.dg/contracts/contracts-ignore1.C: New test.
* g++.dg/contracts/contracts-ignore2.C: New test.
* g++.dg/contracts/contracts-large-return.C: New test.
* g++.dg/contracts/contracts-multiline1.C: New test.
* g++.dg/contracts/contracts-multiple-inheritance1.C: New test.
* g++.dg/contracts/contracts-multiple-inheritance2.C: New test.
* g++.dg/contracts/contracts-nested-class1.C: New test.
* g++.dg/contracts/contracts-nested-class2.C: New test.
* g++.dg/contracts/contracts-nocopy1.C: New test.
* g++.dg/contracts/contracts-override.C: New test.
* g++.dg/contracts/contracts-post1.C: New test.
* g++.dg/contracts/contracts-post2.C: New test.
* g++.dg/contracts/contracts-post3.C: New test.
* g++.dg/contracts/contracts-post4.C: New test.
* g++.dg/contracts/contracts-post5.C: New test.
* g++.dg/contracts/contracts-post6.C: New test.
* g++.dg/contracts/contracts-pre1.C: New test.
* g++.dg/contracts/contracts-pre10.C: New test.
* g++.dg/contracts/contracts-pre2.C: New test.
* g++.dg/contracts/contracts-pre2a1.C: New test.
* g++.dg/contracts/contracts-pre2a2.C: New test.
* g++.dg/contracts/contracts-pre3.C: New test.
* g++.dg/contracts/contracts-pre4.C: New test.
* g++.dg/contracts/contracts-pre5.C: New test.
* g++.dg/contracts/contracts-pre6.C: New test.
* g++.dg/contracts/contracts-pre7.C: New test.
* g++.dg/contracts/contracts-pre9.C: New test.
* g++.dg/contracts/contracts-redecl1.C: New test.
* g++.dg/contracts/contracts-redecl2.C: New test.
* g++.dg/contracts/contracts-redecl3.C: New test.
* g++.dg/contracts/contracts-redecl4.C: New test.
* g++.dg/contracts/contracts-redecl5.C: New test.
* g++.dg/contracts/contracts-redecl6.C: New test.
* g++.dg/contracts/contracts-redecl7.C: New test.
* g++.dg/contracts/contracts-redecl8.C: New test.
* g++.dg/contracts/contracts-tmpl-attr1.C: New test.
* g++.dg/contracts/contracts-tmpl-spec1.C: New test.
* g++.dg/contracts/contracts-tmpl-spec2.C: New test.
* g++.dg/contracts/contracts-tmpl-spec3.C: New test.
* g++.dg/contracts/contracts1.C: New test.
* g++.dg/contracts/contracts10.C: New test.
* g++.dg/contracts/contracts11.C: New test.
* g++.dg/contracts/contracts12.C: New test.
* g++.dg/contracts/contracts13.C: New test.
* g++.dg/contracts/contracts14.C: New test.
* g++.dg/contracts/contracts15.C: New test.
* g++.dg/contracts/contracts16.C: New test.
* g++.dg/contracts/contracts17.C: New test.
* g++.dg/contracts/contracts18.C: New test.
* g++.dg/contracts/contracts19.C: New test.
* g++.dg/contracts/contracts2.C: New test.
* g++.dg/contracts/contracts20.C: New test.
* g++.dg/contracts/contracts22.C: New test.
* g++.dg/contracts/contracts24.C: New test.
* g++.dg/contracts/contracts25.C: New test.
* g++.dg/contracts/contracts3.C: New test.
* g++.dg/contracts/contracts35.C: New test.
* g++.dg/contracts/contracts4.C: New test.
* g++.dg/contracts/contracts5.C: New test.
* g++.dg/contracts/contracts6.C: New test.
* g++.dg/contracts/contracts7.C: New test.
* g++.dg/contracts/contracts8.C: New test.
* g++.dg/contracts/contracts9.C: New test.
* g++.dg/modules/contracts-1_a.C: New test.
* g++.dg/modules/contracts-1_b.C: New test.
* g++.dg/modules/contracts-2_a.C: New test.
* g++.dg/modules/contracts-2_b.C: New test.
* g++.dg/modules/contracts-2_c.C: New test.
* g++.dg/modules/contracts-3_a.C: New test.
* g++.dg/modules/contracts-3_b.C: New test.
* g++.dg/modules/contracts-4_a.C: New test.
* g++.dg/modules/contracts-4_b.C: New test.
* g++.dg/modules/contracts-4_c.C: New test.
* g++.dg/modules/contracts-4_d.C: New test.
* g++.dg/modules/contracts-tpl-friend-1_a.C: New test.
* g++.dg/modules/contracts-tpl-friend-1_b.C: New test.
* g++.dg/contracts/backtrace_handler/Makefile: New test.
* g++.dg/contracts/backtrace_handler/README: New test.
* g++.dg/contracts/backtrace_handler/example_out.txt: New test.
* g++.dg/contracts/backtrace_handler/example_pretty.txt: New test.
* g++.dg/contracts/backtrace_handler/prettytrace.sh: New test.
* g++.dg/contracts/except_preload_handler/Makefile: New test.
* g++.dg/contracts/except_preload_handler/README: New test.
* g++.dg/contracts/except_preload_handler/assert_fail.cpp: New test.
* g++.dg/contracts/except_preload_handler/handle_contract_violation.cpp: New test.
* g++.dg/contracts/noexcept_preload_handler/Makefile: New test.
* g++.dg/contracts/noexcept_preload_handler/README: New test.
* g++.dg/contracts/noexcept_preload_handler/assert_fail.cpp: New test.
* g++.dg/contracts/noexcept_preload_handler/handle_contract_violation.cpp: New test.
* g++.dg/contracts/preload_handler/Makefile: New test.
* g++.dg/contracts/preload_handler/README: New test.
* g++.dg/contracts/preload_handler/assert_fail.cpp: New test.
* g++.dg/contracts/preload_handler/handle_contract_violation.cpp: New test.
* g++.dg/contracts/preload_nocontinue_handler/Makefile: New test.
* g++.dg/contracts/preload_nocontinue_handler/README: New test.
* g++.dg/contracts/preload_nocontinue_handler/assert_fail.cpp: New test.
* g++.dg/contracts/preload_nocontinue_handler/handle_contract_violation.cpp: New test.
* g++.dg/contracts/preload_nocontinue_handler/nocontinue.cpp: New test.
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This patch implements C++23 P2448, which lifts more restrictions on the
constexpr keyword. It's effectively going the way of being just a hint
(hello, inline!).
This gist is relatively simple: in C++23, a constexpr function's return
type/parameter type doesn't have to be a literal type; and you can have
a constexpr function for which no invocation satisfies the requirements
of a core constant expression. For example,
void f(int& i); // not constexpr
constexpr void g(int& i) {
f(i); // unconditionally calls a non-constexpr function
}
is now OK, even though there isn't an invocation of 'g' that would be
a constant expression. Maybe 'f' will be made constexpr soon, or maybe
this depends on the version of C++ used, and similar. The patch is
unfortunately not that trivial. The important bit is to use the new
require_potential_rvalue_constant_expression_fncheck in
maybe_save_constexpr_fundef (and where appropriate). It has a new flag
that says that we're checking the body of a constexpr function, and in
that case it's OK to find constructs that aren't a constant expression.
Since it's useful to be able to check for problematic constructs even
in C++23, this patch implements a new warning, -Winvalid-constexpr,
which is a pedwarn turned on by default in C++20 and earlier, and which
can be turned on in C++23 as well, in which case it's an ordinary warning.
This I implemented by using the new function constexpr_error, used in
p_c_e_1 and friends. (In some cases I believe fundef_p will be always
false (= hard error), but it made sense to me to be consistent and use
constexpr_error throughout p_c_e_1.)
While working on this I think I found a bug, see constexpr-nonlit15.C
and <https://gcc.gnu.org/PR107598>. This patch doesn't address that.
This patch includes changes to diagnose the problem if the user doesn't
use -Winvalid-constexpr and calls a constexpr function that in fact isn't
constexpr-ready yet: maybe_save_constexpr_fundef registers the function
if warn_invalid_constexpr is 0 and explain_invalid_constexpr_fn then
gives the diagnostic.
PR c++/106649
gcc/c-family/ChangeLog:
* c-cppbuiltin.cc (c_cpp_builtins): Update value of __cpp_constexpr for
C++23.
* c-opts.cc (c_common_post_options): Set warn_invalid_constexpr
depending on cxx_dialect.
* c.opt (Winvalid-constexpr): New option.
gcc/cp/ChangeLog:
* constexpr.cc (constexpr_error): New function.
(is_valid_constexpr_fn): Use constexpr_error.
(maybe_save_constexpr_fundef): Call
require_potential_rvalue_constant_expression_fncheck rather than
require_potential_rvalue_constant_expression. Register the
function if -Wno-invalid-constexpr was specified.
(explain_invalid_constexpr_fn): Don't return early if a function marked
'constexpr' that isn't actually a constant expression was called.
(non_const_var_error): Add a bool parameter. Use constexpr_error.
(inline_asm_in_constexpr_error): Likewise.
(cxx_eval_constant_expression): Adjust calls to non_const_var_error
and inline_asm_in_constexpr_error.
(potential_constant_expression_1): Add a bool parameter. Use
constexpr_error.
(require_potential_rvalue_constant_expression_fncheck): New function.
* cp-tree.h (require_potential_rvalue_constant_expression_fncheck):
Declare.
* method.cc (struct comp_info): Call
require_potential_rvalue_constant_expression_fncheck rather than
require_potential_rvalue_constant_expression.
gcc/ChangeLog:
* doc/invoke.texi: Document -Winvalid-constexpr.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-ctor2.C: Expect an error in c++20_down only.
* g++.dg/cpp0x/constexpr-default-ctor.C: Likewise.
* g++.dg/cpp0x/constexpr-diag3.C: Likewise.
* g++.dg/cpp0x/constexpr-ex1.C: Likewise.
* g++.dg/cpp0x/constexpr-friend.C: Likewise.
* g++.dg/cpp0x/constexpr-generated1.C: Likewise.
* g++.dg/cpp0x/constexpr-ice5.C: Likewise.
* g++.dg/cpp0x/constexpr-ice6.C: Likewise.
* g++.dg/cpp0x/constexpr-memfn1.C: Likewise.
* g++.dg/cpp0x/constexpr-neg2.C: Likewise.
* g++.dg/cpp0x/constexpr-non-const-arg.C: Likewise.
* g++.dg/cpp0x/constexpr-reinterpret1.C: Likewise.
* g++.dg/cpp0x/pr65327.C: Likewise.
* g++.dg/cpp1y/constexpr-105050.C: Likewise.
* g++.dg/cpp1y/constexpr-89285-2.C: Likewise.
* g++.dg/cpp1y/constexpr-89285.C: Likewise.
* g++.dg/cpp1y/constexpr-89785-2.C: Likewise.
* g++.dg/cpp1y/constexpr-neg1.C: Likewise.
* g++.dg/cpp1y/constexpr-nsdmi7b.C: Likewise.
* g++.dg/cpp1y/constexpr-throw.C: Likewise.
* g++.dg/cpp23/constexpr-nonlit3.C: Remove dg-error.
* g++.dg/cpp23/constexpr-nonlit6.C: Call the test functions.
* g++.dg/cpp23/feat-cxx2b.C: Adjust the expected value of
__cpp_constexpr.
* g++.dg/cpp2a/consteval3.C: Remove dg-error.
* g++.dg/cpp2a/constexpr-new7.C: Expect an error in c++20_down only.
* g++.dg/cpp2a/constexpr-try5.C: Remove dg-error.
* g++.dg/cpp2a/spaceship-constexpr1.C: Expect an error in c++20_down
only.
* g++.dg/cpp2a/spaceship-eq3.C: Likewise.
* g++.dg/diagnostic/constexpr1.C: Remove dg-error.
* g++.dg/gomp/pr79664.C: Use -Winvalid-constexpr -pedantic-errors.
* g++.dg/ubsan/vptr-4.C: Likewise.
* g++.dg/cpp23/constexpr-nonlit10.C: New test.
* g++.dg/cpp23/constexpr-nonlit11.C: New test.
* g++.dg/cpp23/constexpr-nonlit12.C: New test.
* g++.dg/cpp23/constexpr-nonlit13.C: New test.
* g++.dg/cpp23/constexpr-nonlit14.C: New test.
* g++.dg/cpp23/constexpr-nonlit15.C: New test.
* g++.dg/cpp23/constexpr-nonlit16.C: New test.
* g++.dg/cpp23/constexpr-nonlit8.C: New test.
* g++.dg/cpp23/constexpr-nonlit9.C: New test.
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It seems the only and original purpose of tsubst_copy_and_build's
integral_constant_expression_p boolean parameter (added in r116276, which
predates the constexpr machinery) is to diagnose certain constructs that
aren't allowed to appear in a C++98 integral constant expression
context, specifically casts to a non-integral type (diagnosed from the
*_CAST_EXPR case of tsubst_copy_and_build) or dependent names that
resolve to a non-constant decl (diagnosed from the IDENTIFIER_NODE case
of tsubst_copy_and_build). The parameter has no effect outside of C++98
AFAICT.
But diagnosing such constructs should arguably be the job of the constexpr
machinery (e.g. is_constant_expression) after substitution, and doing it
during substitution by way of an additional parameter complicates the
API of this workhorse function for what amounts to a couple of archaic
C++98 restrictions. And it seems is_constant_expression already does a
good job of diagnosing the aforementioned two constructs in C++98 mode,
at least as far as our testsuite is concerned.
So this patch removes this parameter from tsubst_copy_and_build,
tsubst_expr and tsubst_copy_and_build_call_args. The only interesting
changes are to potential_constant_expression_1 and the IDENTIFIER_NODE
and *_CAST_EXPR cases of tsubst_copy_and_build; the rest are mechanical
adjustments to the functions' signatures and their call sites.
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1)
<case *_CAST_EXPR>: Use
cast_valid_in_integral_constant_expression_p instead of
open coding it.
* constraint.cc (tsubst_valid_expression_requirement): Adjust
calls to tsubst_copy_and_build and tsubst_expr.
(tsubst_constraint): Likewise.
(satisfy_atom): Likewise.
(diagnose_trait_expr): Likewise.
* cp-tree.h (tsubst_copy_and_build): Remove i_c_e_p parameter.
(tsubst_expr): Likewise.
* init.cc (get_nsdmi): Adjust calls to tsubst_copy_and_build
and tsubst_expr.
* pt.cc (expand_integer_pack): Likewise.
(instantiate_non_dependent_expr_internal): Likewise.
(tsubst_friend_function): Likewise.
(tsubst_attribute): Likewise.
(instantiate_class_template): Likewise.
(tsubst_template_arg): Likewise.
(gen_elem_of_pack_expansion_instantiation): Likewise.
(tsubst_fold_expr_init): Likewise.
(tsubst_pack_expansion): Likewise.
(tsubst_default_argument): Likewise.
(tsubst_function_decl): Likewise.
(tsubst_decl): Likewise.
(tsubst_arg_types): Likewise.
(tsubst_exception_specification): Likewise.
(tsubst): Likewise.
(tsubst_init): Likewise.
(tsubst_copy): Likewise.
(tsubst_omp_clause_decl): Likewise.
(tsubst_omp_clauses): Likewise.
(tsubst_copy_asm_operands): Likewise.
(tsubst_omp_for_iterator): Likewise.
(tsubst_expr): Likewise. Remove i_c_e_p parameter.
(tsubst_omp_udr): Likewise.
(tsubst_non_call_postfix_expression): Likewise. Remove i_c_e_p parameter.
(tsubst_lambda_expr): Likewise.
(tsubst_copy_and_build_call_args): Likewise.
(tsubst_copy_and_build): Likewise. Remove i_c_e_p parameter.
<case IDENTIFIER_NODE>: Adjust call to finish_id_expression
following removal of i_c_e_p.
<case *_CAST_EXPR>: Remove C++98-specific cast validity check
guarded by i_c_e_p.
(maybe_instantiate_noexcept): Adjust calls to
tsubst_copy_and_build and tsubst_expr.
(instantiate_body): Likewise.
(instantiate_decl): Likewise.
(tsubst_initializer_list): Likewise.
(tsubst_enum): Likewise.
gcc/objcp/ChangeLog:
* objcp-lang.cc (objcp_tsubst_copy_and_build): Adjust calls to
tsubst_copy_and_build and tsubst_expr.
gcc/testsuite/ChangeLog:
* g++.dg/template/crash55.C: Don't expect additional
C++98-specific diagnostics.
* g++.dg/template/ref3.C: Remove C++98-specific xfail.
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Still want the conversion to bool.
gcc/cp/ChangeLog:
* constexpr.cc (find_failing_clause_r): Re-add the call to
contextual_conv_bool.
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The initial [[assume]] support avoided evaluating assumes with
TREE_SIDE_EFFECTS set, such as calls, because we don't want any side-effects
that change the constexpr state. This patch allows us to evaluate
expressions with that flag set by tracking which variables the evaluation is
allowed to modify, and giving up if it tries to touch any others.
I considered allowing changes to other variables and then rolling them back,
but that seems like a rare enough situation that it doesn't seem worth
working to handle nicely at this point.
gcc/cp/ChangeLog:
* constexpr.cc (class constexpr_global_ctx): Add modifiable field,
get_value, get_value_ptr, put_value, remove_value, flush_modifiable
member functions.
(class modifiable_tracker): New.
(cxx_eval_internal_function): Use it.
(diagnose_failing_condition): Strip CLEANUP_POINT_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/attr-assume9.C: New test.
* g++.dg/cpp23/attr-assume10.C: New test.
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I noticed that we were printing "the comparison reduces to (x == 42)" when
we should be able to give the value of x. Fixed by doing the same
evaluation in diagnose_failing_condition that we already do in
find_failing_clause.
gcc/cp/ChangeLog:
* constexpr.cc (fold_operand): New function.
(find_failing_clause_r): Add const.
(find_failing_clause): Add const.
(diagnose_failing_condition): Add ctx parameter.
(cxx_eval_internal_function): Pass it.
* semantics.cc (diagnose_failing_condition): Move to constexpr.cc.
* cp-tree.h: Adjust.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/attr-assume2.C: Expect constant values.
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inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek <jakub@redhat.com>
PR c++/105774
* constexpr.cc (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
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cxx_eval_constant_expression [PR107295]
The excess precision support broke building skia (dependency of firefox)
on ia32 (it has something like the a constexpr variable), but as the other
cases show, it is actually a preexisting problem if one uses casts from
constants with wider floating point types.
The problem is that cxx_eval_constant_expression tries to short-cut
processing of TREE_CONSTANT CONSTRUCTORs if they satisfy
reduced_constant_expression_p - instead of calling cxx_eval_bare_aggregate
on them it just verifies flags and if they are TREE_CONSTANT even after
that, just fold.
Now, on the testcase we have a TREE_CONSTANT CONSTRUCTOR containing
TREE_CONSTANT NOP_EXPR of REAL_CST. And, fold, which isn't recursive,
doesn't optimize that into VECTOR_CST, while later on we are only able
to optimize VECTOR_CST arithmetics, not arithmetics with vector
CONSTRUCTORs.
The following patch fixes that by rejecting CONSTRUCTORs with vector type
in reduced_constant_expression_p regardless of whether they have
CONSTRUCTOR_NO_CLEARING set or not, folding result in cxx_eval_bare_aggregate
even if nothing has changed but it wasn't non-constant and removing folding
from the TREE_CONSTANT reduced_constant_expression_p short-cut.
2022-10-21 Jakub Jelinek <jakub@redhat.com>
PR c++/107295
* constexpr.cc (reduced_constant_expression_p) <case CONSTRUCTOR>:
Return false for VECTOR_TYPE CONSTRUCTORs even without
CONSTRUCTOR_NO_CLEARING set on them.
(cxx_eval_bare_aggregate): If constant but !changed, fold before
returning VECTOR_TYPE_P CONSTRUCTOR.
(cxx_eval_constant_expression) <case CONSTRUCTOR>: Don't fold
TREE_CONSTANT CONSTRUCTOR, just return it.
* g++.dg/ext/vector42.C: New test.
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The FUNCTION_DECL we build for __dynamic_cast has an empty DECL_CONTEXT
but trees_out::tree_node expects FUNCTION_DECLs to have non-empty
DECL_CONTEXT, thus we crash when streaming out the dynamic_cast in the
below testcase.
This patch naively fixes this by setting DECL_CONTEXT for __dynamic_cast
appropriately. I suppose we should push it into the namespace too, like
we do for __cxa_atexit which is similarly lazily declared.
PR c++/106304
gcc/cp/ChangeLog:
* constexpr.cc (cxx_dynamic_cast_fn_p): Check for abi_node
instead of global_namespace.
* rtti.cc (build_dynamic_cast_1): Set DECL_CONTEXT and
DECL_SOURCE_LOCATION when building dynamic_cast_node. Push
it into the namespace.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr106304_a.C: New test.
* g++.dg/modules/pr106304_b.C: New test.
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The following patch implements excess precision support for C++.
Like for C, it uses EXCESS_PRECISION_EXPR tree to say that its operand
is evaluated in excess precision and what the semantic type of the
expression is.
In most places I've followed what the C FE does in similar spots, so
e.g. for binary ops if one or both operands are already
EXCESS_PRECISION_EXPR, strip those away or for operations that might need
excess precision (+, -, *, /) check if the operands should use excess
precision and convert to that type and at the end wrap into
EXCESS_PRECISION_EXPR with the common semantic type.
This patch follows the C99 handling where it differs from C11 handling.
There are some cases which needed to be handled differently, the C FE can
just strip EXCESS_PRECISION_EXPR (replace it with its operand) when handling
explicit cast, but that IMHO isn't right for C++ - the discovery what exact
conversion should be used (e.g. if user conversion or standard or their
sequence) should be decided based on the semantic type (i.e. type of
EXCESS_PRECISION_EXPR), and that decision continues in convert_like* where
we pick the right user conversion, again, if say some class has ctor
from double and long double and we are on ia32 with standard excess
precision promoting float/double to long double, then we should pick the
ctor from double. Or when some other class has ctor from just double,
and EXCESS_PRECISION_EXPR semantic type is float, we should choose the
user ctor from double, but actually just convert the long double excess
precision to double and not to float first. We need to make sure
even identity conversion converts from excess precision to the semantic one
though, but if identity is chained with other conversions, we don't want
the identity next_conversion to drop to semantic precision only to widen
afterwards.
The existing testcases tweaks were for cases on i686-linux where excess
precision breaks those tests, e.g. if we have
double d = 4.2;
if (d == 4.2)
then it does the expected thing only with -fexcess-precision=fast,
because with -fexcess-precision=standard it is actually
double d = 4.2;
if ((long double) d == 4.2L)
where 4.2L is different from 4.2. I've added -fexcess-precision=fast
to some tests and changed other tests to use constants that are exactly
representable and don't suffer from these excess precision issues.
There is one exception, pr68180.C looks like a bug in the patch which is
also present in the C FE (so I'd like to get it resolved incrementally
in both). Reduced testcase:
typedef float __attribute__((vector_size (16))) float32x4_t;
float32x4_t foo(float32x4_t x, float y) { return x + y; }
with -m32 -std=c11 -Wno-psabi or -m32 -std=c++17 -Wno-psabi
it is rejected with:
pr68180.c:2:52: error: conversion of scalar ‘long double’ to vector ‘float32x4_t’ {aka ‘__vector(4) float’} involves truncation
but without excess precision (say just -std=c11 -Wno-psabi or -std=c++17 -Wno-psabi)
it is accepted. Perhaps we should pass down the semantic type to
scalar_to_vector and use the semantic type rather than excess precision type
in the diagnostics.
2022-10-14 Jakub Jelinek <jakub@redhat.com>
PR middle-end/323
PR c++/107097
gcc/
* doc/invoke.texi (-fexcess-precision=standard): Mention that the
option now also works in C++.
gcc/c-family/
* c-common.def (EXCESS_PRECISION_EXPR): Remove comment part about
the tree being specific to C/ObjC.
* c-opts.cc (c_common_post_options): Handle flag_excess_precision
in C++ the same as in C.
* c-lex.cc (interpret_float): Set const_type to excess_precision ()
even for C++.
gcc/cp/
* parser.cc (cp_parser_primary_expression): Handle
EXCESS_PRECISION_EXPR with REAL_CST operand the same as REAL_CST.
* cvt.cc (cp_ep_convert_and_check): New function.
* call.cc (build_conditional_expr): Add excess precision support.
When type_after_usual_arithmetic_conversions returns error_mark_node,
use gcc_checking_assert that it is because of uncomparable floating
point ranks instead of checking all those conditions and make it
work also with complex types.
(convert_like_internal): Likewise. Add NESTED_P argument, pass true
to recursive calls to convert_like.
(convert_like): Add NESTED_P argument, pass it through to
convert_like_internal. For other overload pass false to it.
(convert_like_with_context): Pass false to NESTED_P.
(convert_arg_to_ellipsis): Add excess precision support.
(magic_varargs_p): For __builtin_is{finite,inf,inf_sign,nan,normal}
and __builtin_fpclassify return 2 instead of 1, document what it
means.
(build_over_call): Don't handle former magic 2 which is no longer
used, instead for magic 1 remove EXCESS_PRECISION_EXPR.
(perform_direct_initialization_if_possible): Pass false to NESTED_P
convert_like argument.
* constexpr.cc (cxx_eval_constant_expression): Handle
EXCESS_PRECISION_EXPR.
(potential_constant_expression_1): Likewise.
* pt.cc (tsubst_copy, tsubst_copy_and_build): Likewise.
* cp-tree.h (cp_ep_convert_and_check): Declare.
* cp-gimplify.cc (cp_fold): Handle EXCESS_PRECISION_EXPR.
* typeck.cc (cp_common_type): For COMPLEX_TYPEs, return error_mark_node
if recursive call returned it.
(convert_arguments): For magic 1 remove EXCESS_PRECISION_EXPR.
(cp_build_binary_op): Add excess precision support. When
cp_common_type returns error_mark_node, use gcc_checking_assert that
it is because of uncomparable floating point ranks instead of checking
all those conditions and make it work also with complex types.
(cp_build_unary_op): Likewise.
(cp_build_compound_expr): Likewise.
(build_static_cast_1): Remove EXCESS_PRECISION_EXPR.
gcc/testsuite/
* gcc.target/i386/excess-precision-1.c: For C++ wrap abort and
exit declarations into extern "C" block.
* gcc.target/i386/excess-precision-2.c: Likewise.
* gcc.target/i386/excess-precision-3.c: Likewise. Remove
check_float_nonproto and check_double_nonproto tests for C++.
* gcc.target/i386/excess-precision-7.c: For C++ wrap abort and
exit declarations into extern "C" block.
* gcc.target/i386/excess-precision-9.c: Likewise.
* g++.target/i386/excess-precision-1.C: New test.
* g++.target/i386/excess-precision-2.C: New test.
* g++.target/i386/excess-precision-3.C: New test.
* g++.target/i386/excess-precision-4.C: New test.
* g++.target/i386/excess-precision-5.C: New test.
* g++.target/i386/excess-precision-6.C: New test.
* g++.target/i386/excess-precision-7.C: New test.
* g++.target/i386/excess-precision-9.C: New test.
* g++.target/i386/excess-precision-11.C: New test.
* c-c++-common/dfp/convert-bfp-10.c: Add -fexcess-precision=fast
as dg-additional-options.
* c-c++-common/dfp/compare-eq-const.c: Likewise.
* g++.dg/cpp1z/constexpr-96862.C: Likewise.
* g++.dg/cpp1z/decomp12.C (main): Use 2.25 instead of 2.3 to
avoid excess precision differences.
* g++.dg/other/thunk1.C: Add -fexcess-precision=fast
as dg-additional-options.
* g++.dg/vect/pr64410.cc: Likewise.
* g++.dg/cpp1y/pr68180.C: Likewise.
* g++.dg/vect/pr89653.cc: Likewise.
* g++.dg/cpp0x/variadic-tuple.C: Likewise.
* g++.dg/cpp0x/nsdmi-union1.C: Use 4.25 instead of 4.2 to
avoid excess precision differences.
* g++.old-deja/g++.brendan/copy9.C: Add -fexcess-precision=fast
as dg-additional-options.
* g++.old-deja/g++.brendan/overload7.C: Likewise.
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The proposed resolution of CWG2631 extends our current handling of
source_location::current to all consteval functions: default arguments
are not evaluated until they're used in a call, the same should apply to
evaluation of immediate invocations. And similarly for default member
initializers.
Previously we folded source_location::current in cp_fold_r; now we fold all
consteval calls in default arguments/member initializers in bot_replace.
DR 2631
gcc/cp/ChangeLog:
* cp-tree.h (source_location_current_p): Remove.
* name-lookup.h (struct cp_binding_level): Remove
immediate_fn_ctx_p.
* call.cc (in_immediate_context): All default args
and DMI are potentially immediate context.
(immediate_invocation_p): Don't treat source_location specially.
(struct in_consteval_if_p_temp_override): Move to cp-tree.h.
* constexpr.cc (get_nth_callarg): Move to cp-tree.h.
* cp-gimplify.cc (cp_fold_r): Don't fold consteval.
* name-lookup.cc (begin_scope): Don't set immediate_fn_ctx_p.
* parser.cc (cp_parser_lambda_declarator_opt): Likewise.
(cp_parser_direct_declarator): Likewise.
* pt.cc (tsubst_default_argument): Open sk_function_parms level.
* tree.cc (source_location_current_p): Remove.
(bot_replace): Fold consteval here.
(break_out_target_exprs): Handle errors.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/consteval-defarg3.C: New test.
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The following patch implements C++23 P1774R8 - Portable assumptions
paper, by introducing support for [[assume (cond)]]; attribute for C++.
In addition to that the patch adds [[gnu::assume (cond)]]; and
__attribute__((assume (cond))); support to both C and C++.
As described in C++23, the attribute argument is conditional-expression
rather than the usual assignment-expression for attribute arguments,
the condition is contextually converted to bool (for C truthvalue conversion
is done on it) and is never evaluated at runtime.
For C++ constant expression evaluation, I only check the simplest conditions
for undefined behavior, because otherwise I'd need to undo changes to
*ctx->global which happened during the evaluation (but I believe the spec
allows that and we can further improve later).
The patch uses a new internal function, .ASSUME, to hold the condition
in the FEs. At gimplification time, if the condition is simple/without
side-effects, it is gimplified as if (cond) ; else __builtin_unreachable ();
and otherwise for now dropped on the floor. The intent is to incrementally
outline the conditions into separate artificial functions and use
.ASSUME further to tell the ranger and perhaps other optimization passes
about the assumptions, as detailed in the PR.
When implementing it, I found that assume entry hasn't been added to
https://eel.is/c++draft/cpp.cond#6
Jonathan said he'll file a NB comment about it, this patch assumes it
has been added into the table as 202207L when the paper has been voted in.
With the attributes for both C/C++, I'd say we don't need to add
__builtin_assume with similar purpose, especially when __builtin_assume
in LLVM is just weird. It is strange for side-effects in function call's
argument not to be evaluated, and LLVM in that case (annoyingly) warns
and ignores the side-effects (but doesn't do then anything with it),
if there are no side-effects, it will work like our
if (!cond) __builtin_unreachable ();
2022-10-06 Jakub Jelinek <jakub@redhat.com>
PR c++/106654
gcc/
* internal-fn.def (ASSUME): New internal function.
* internal-fn.h (expand_ASSUME): Declare.
* internal-fn.cc (expand_ASSUME): Define.
* gimplify.cc (gimplify_call_expr): Gimplify IFN_ASSUME.
* fold-const.h (simple_condition_p): Declare.
* fold-const.cc (simple_operand_p_2): Rename to ...
(simple_condition_p): ... this. Remove forward declaration.
No longer static. Adjust function comment and fix a typo in it.
Adjust recursive call.
(simple_operand_p): Adjust function comment.
(fold_truth_andor): Adjust simple_operand_p_2 callers to call
simple_condition_p.
* doc/extend.texi: Document assume attribute. Move fallthrough
attribute example to its section.
gcc/c-family/
* c-attribs.cc (handle_assume_attribute): New function.
(c_common_attribute_table): Add entry for assume attribute.
* c-lex.cc (c_common_has_attribute): Handle
__have_cpp_attribute (assume).
gcc/c/
* c-parser.cc (handle_assume_attribute): New function.
(c_parser_declaration_or_fndef): Handle assume attribute.
(c_parser_attribute_arguments): Add assume_attr argument,
if true, parse first argument as conditional expression.
(c_parser_gnu_attribute, c_parser_std_attribute): Adjust
c_parser_attribute_arguments callers.
(c_parser_statement_after_labels) <case RID_ATTRIBUTE>: Handle
assume attribute.
gcc/cp/
* cp-tree.h (process_stmt_assume_attribute): Implement C++23
P1774R8 - Portable assumptions. Declare.
(diagnose_failing_condition): Declare.
(find_failing_clause): Likewise.
* parser.cc (assume_attr): New enumerator.
(cp_parser_parenthesized_expression_list): Handle assume_attr.
Remove identifier variable, for id_attr push the identifier into
expression_list right away instead of inserting it before all the
others at the end.
(cp_parser_conditional_expression): New function.
(cp_parser_constant_expression): Use it.
(cp_parser_statement): Handle assume attribute.
(cp_parser_expression_statement): Likewise.
(cp_parser_gnu_attribute_list): Use assume_attr for assume
attribute.
(cp_parser_std_attribute): Likewise. Handle standard assume
attribute like gnu::assume.
* cp-gimplify.cc (process_stmt_assume_attribute): New function.
* constexpr.cc: Include fold-const.h.
(find_failing_clause_r, find_failing_clause): New functions,
moved from semantics.cc with ctx argument added and if non-NULL,
call cxx_eval_constant_expression rather than fold_non_dependent_expr.
(cxx_eval_internal_function): Handle IFN_ASSUME.
(potential_constant_expression_1): Likewise.
* pt.cc (tsubst_copy_and_build): Likewise.
* semantics.cc (diagnose_failing_condition): New function.
(find_failing_clause_r, find_failing_clause): Moved to constexpr.cc.
(finish_static_assert): Use it. Add auto_diagnostic_group.
gcc/testsuite/
* gcc.dg/attr-assume-1.c: New test.
* gcc.dg/attr-assume-2.c: New test.
* gcc.dg/attr-assume-3.c: New test.
* g++.dg/cpp2a/feat-cxx2a.C: Add colon to C++20 features
comment, add C++20 attributes comment and move C++20
new features after the attributes before them.
* g++.dg/cpp23/feat-cxx2b.C: Likewise. Test
__has_cpp_attribute(assume).
* g++.dg/cpp23/attr-assume1.C: New test.
* g++.dg/cpp23/attr-assume2.C: New test.
* g++.dg/cpp23/attr-assume3.C: New test.
* g++.dg/cpp23/attr-assume4.C: New test.
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An experiment led me to notice that in some cases we were ending up with
TARGET_EXPR initialized by TARGET_EXPR, which isn't useful.
The target_expr_needs_replace change won't make a difference in most cases,
since cp_genericize_init will have already expanded VEC_INIT_EXPR by the
time we consider it, but it is correct.
gcc/cp/ChangeLog:
* cp-gimplify.cc (cp_fold_r) [TARGET_EXPR]: Collapse
TARGET_EXPR within TARGET_EXPR.
* constexpr.cc (cxx_eval_outermost_constant_expr): Avoid
adding redundant TARGET_EXPR.
* cp-tree.h (target_expr_needs_replace): VEC_INIT_EXPR doesn't.
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We were overlooking non-potentially-constant bits in variable initializer
because we didn't walk into DECL_INITIAL.
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1): Look into
DECL_INITIAL. Use location wrappers.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-local4.C: Expect error sooner.
* g++.dg/cpp2a/consteval24.C: Likewise.
* g++.dg/cpp2a/consteval7.C: Likewise.
* g++.dg/cpp2a/inline-asm3.C: Likewise.
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This patch permits accessing 'mutable' members of local objects during
constexpr evaluation, while continuing to reject it for global objects
(as in the last line of cpp0x/constexpr-mutable1.C). To distinguish
between the two cases, it looks like it suffices to just check
CONSTRUCTOR_MUTABLE_POSION in cxx_eval_component_reference before
deciding to reject a DECL_MUTABLE_P member access.
PR c++/92505
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_component_reference): Check non_constant_p
sooner. In C++14 or later, reject a DECL_MUTABLE_P member access
only if CONSTRUCTOR_MUTABLE_POISION is also set.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-mutable3.C: New test.
* g++.dg/cpp1y/constexpr-mutable1.C: New test.
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The functions
abstract_virtuals_error
cxx_constant_value
get_target_expr
instantiate_non_dependent_expr
require_complete_type
are each just a non-SFINAE-enabled wrapper for the corresponding
SFINAE-enabled version that's suffixed by '_sfinae'. But this suffix is
at best redundant since a 'complain' parameter already broadly conveys
that a function is SFINAE-enabled, and having two such versions of a
function is less concise than just using a default argument for 'complain'
(and arguably no less mistake prone).
So this patch squashes the two versions of each of the above functions
by adding a default 'complain' argument to the SFINAE-enabled version
whose '_sfinae' suffix we then remove.
gcc/cp/ChangeLog:
* call.cc (build_conditional_expr): Adjust calls to
'_sfinae'-suffixed functions.
(build_temp): Likewise.
(convert_like_internal): Likewise.
(convert_arg_to_ellipsis): Likewise.
(build_over_call): Likewise.
(build_cxx_call): Likewise.
(build_new_method_call): Likewise.
* constexpr.cc (cxx_eval_outermost_constant_expr): Likewise.
(cxx_constant_value_sfinae): Rename to ...
(cxx_constant_value): ... this. Document its default arguments.
(fold_non_dependent_expr): Adjust function comment.
* cp-tree.h (instantiate_non_dependent_expr_sfinae): Rename to ...
(instantiate_non_dependent_expr): ... this. Give its 'complain'
parameter a default argument.
(get_target_expr_sfinae, get_target_expr): Likewise.
(require_complete_type_sfinae, require_complete_type): Likewise.
(abstract_virtuals_error_sfinae, abstract_virtuals_error):
Likewise.
(cxx_constant_value_sfinae, cxx_constant_value): Likewise.
* cvt.cc (build_up_reference): Adjust calls to '_sfinae'-suffixed
functions.
(ocp_convert): Likewise.
* decl.cc (build_explicit_specifier): Likewise.
* except.cc (build_noexcept_spec): Likewise.
* init.cc (build_new_1): Likewise.
* pt.cc (expand_integer_pack): Likewise.
(instantiate_non_dependent_expr_internal): Adjust function
comment.
(instantiate_non_dependent_expr): Rename to ...
(instantiate_non_dependent_expr_sfinae): ... this. Document its
default argument.
(tsubst_init): Adjust calls to '_sfinae'-suffixed functions.
(fold_targs_r): Likewise.
* semantics.cc (finish_compound_literal): Likewise.
(finish_decltype_type): Likewise.
(cp_build_bit_cast): Likewise.
* tree.cc (build_cplus_new): Likewise.
(get_target_expr): Rename to ...
(get_target_expr_sfinae): ... this. Document its default
argument.
* typeck.cc (require_complete_type): Rename to ...
(require_complete_type_sfinae): ... this. Document its default
argument.
(cp_build_array_ref): Adjust calls to '_sfinae'-suffixed
functions.
(convert_arguments): Likewise.
(cp_build_binary_op): Likewise.
(build_static_cast_1): Likewise.
(cp_build_modify_expr): Likewise.
(convert_for_initialization): Likewise.
* typeck2.cc (abstract_virtuals_error): Rename to ...
(abstract_virtuals_error_sfinae): ... this. Document its default
argument.
(build_functional_cast_1): Adjust calls to '_sfinae'-suffixed
functions.
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[PR88174]
We claim we support P0415R1 (constexpr complex), but e.g.
#include <complex>
constexpr bool
foo ()
{
std::complex<double> a (1.0, 2.0);
a += 3.0;
a.real (6.0);
return a.real () == 6.0 && a.imag () == 2.0;
}
static_assert (foo ());
fails with
test.C:12:20: error: non-constant condition for static assertion
12 | static_assert (foo ());
| ~~~~^~
test.C:12:20: in ‘constexpr’ expansion of ‘foo()’
test.C:8:10: in ‘constexpr’ expansion of ‘a.std::complex<double>::real(6.0e+0)’
test.C:12:20: error: modification of ‘__real__ a.std::complex<double>::_M_value’ is not a constant expression
The problem is we don't handle REALPART_EXPR and IMAGPART_EXPR
in cxx_eval_store_expression.
The following patch attempts to support it (with a requirement
that those are the outermost expressions, ARRAY_REF/COMPONENT_REF
etc. are just not possible on the result of these, BIT_FIELD_REF
would be theoretically possible if trying to extract some bits
from one part of a complex int, but I don't see how it could appear
in the FE trees.
For these references, the code handles value being COMPLEX_CST,
COMPLEX_EXPR or CONSTRUCTOR_NO_CLEARING empty CONSTRUCTOR (what we use
to represent uninitialized values for C++20 and later) and the
code starts by rewriting it to COMPLEX_EXPR, so that we can freely
adjust the individual parts and later on possibly optimize it back
to COMPLEX_CST if both halves are constant.
2022-08-07 Jakub Jelinek <jakub@redhat.com>
PR c++/88174
* constexpr.cc (cxx_eval_store_expression): Handle REALPART_EXPR
and IMAGPART_EXPR. Change ctors from releasing_vec to
auto_vec<tree *>, adjust all uses. For !preeval, update ctors
vector.
* g++.dg/cpp1y/constexpr-complex1.C: New test.
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Here the CONSTRUCTOR we were providing for D{} had an entry for the B base
subobject at offset 0 following the entry for the C base, causing
output_constructor_regular_field to ICE due to going backwards. It might be
nice for that function to be more tolerant of empty fields, but it also
seems reasonable for the front end to prune the useless entry.
PR c++/106369
gcc/cp/ChangeLog:
* constexpr.cc (reduced_constant_expression_p): Return false
if a CONSTRUCTOR initializes an empty field.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-lambda27.C: New test.
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In this problem, we are failing to properly perform copy elision with
a conditional operator, so this:
constexpr A a = true ? A{} : A{};
fails with:
error: 'A{((const A*)(&<anonymous>))}' is not a constant expression
The whole initializer is
TARGET_EXPR <D.2395, 1 ? TARGET_EXPR <D.2393, {.p=(const struct A *) &<PLACEHOLDER_EXPR struct A>}> : TARGET_EXPR <D.2394, {.p=(const struct A *) &<PLACEHOLDER_EXPR struct A>}>>
where the outermost TARGET_EXPR is elided, but not the nested ones.
Then we end up replacing the PLACEHOLDER_EXPRs with the temporaries the
TARGET_EXPRs represent, which is precisely what should *not* happen with
copy elision.
I've tried the approach of tweaking ctx->object, but I ran into gazillion
problems with that. I thought that I would let cxx_eval_constant_expression
/TARGET_EXPR create a new object only when ctx->object was null, then
adjust setting of ctx->object in places like cxx_bind_parameters_in_call
and cxx_eval_component_reference but that failed completely. Sometimes
ctx->object has to be reset, sometimes it cannot be reset, 'this' needed
special handling, etc. I gave up.
Instead, this patch strips TARGET_EXPRs from the operands of ?: like
we do in various other places in constexpr.c.
PR c++/105550
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_conditional_expression): Strip TARGET_EXPRs.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/nsdmi-aggr16.C: Remove FIXME.
* g++.dg/cpp1y/nsdmi-aggr17.C: Remove FIXME.
* g++.dg/cpp0x/constexpr-elision1.C: New test.
* g++.dg/cpp1y/constexpr-elision1.C: New test.
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When not optimizing, we can't do anything useful with unreachability in
terms of code performance, so we might as well improve debugging by turning
__builtin_unreachable into a trap. I think it also makes sense to do this
when we're explicitly optimizing for the debugging experience.
In the PR richi suggested introducing an -funreachable-traps flag for this.
This functionality is already implemented as -fsanitize=unreachable
-fsanitize-trap=unreachable, and we want to share the implementation, but it
does seem useful to have a separate flag that isn't affected by the various
sanitization controls. -fsanitize=unreachable takes priority over
-funreachable-traps if both are enabled.
Jakub observed that this would slow down -O0 by default from running the
sanopt pass, so this revision avoids the need for sanopt by rewriting calls
introduced by the compiler immediately, and calls written by the user at
fold time. Many of the calls introduced by the compiler are also rewritten
immediately to ubsan calls when not trapping, which fixes ubsan-8b.C;
previously the call to f() was optimized away before sanopt. But this early
rewriting isn't practical for uses of __builtin_unreachable in
devirtualization and such, so sanopt rewriting is still done for
non-trapping sanitize.
PR c++/104642
gcc/ChangeLog:
* common.opt: Add -funreachable-traps.
* doc/invoke.texi (-funreachable-traps): Document it.
* opts.cc (finish_options): Enable at -O0 or -Og.
* tree.cc (build_common_builtin_nodes): Add __builtin_trap.
(builtin_decl_unreachable, build_builtin_unreachable): New.
* tree.h: Declare them.
* ubsan.cc (sanitize_unreachable_fn): Factor out.
(ubsan_instrument_unreachable): Use
gimple_build_builtin_unreachable.
* ubsan.h (sanitize_unreachable_fn): Declare.
* gimple.cc (gimple_build_builtin_unreachable): New.
* gimple.h: Declare it.
* builtins.cc (expand_builtin_unreachable): Add assert.
(fold_builtin_0): Call build_builtin_unreachable.
* sanopt.cc: Don't run for just SANITIZE_RETURN
or SANITIZE_UNREACHABLE when trapping.
* cgraphunit.cc (walk_polymorphic_call_targets): Use new
unreachable functions.
* gimple-fold.cc (gimple_fold_call)
(gimple_get_virt_method_for_vtable)
* ipa-fnsummary.cc (redirect_to_unreachable)
* ipa-prop.cc (ipa_make_edge_direct_to_target)
(ipa_impossible_devirt_target)
* ipa.cc (walk_polymorphic_call_targets)
* tree-cfg.cc (pass_warn_function_return::execute)
(execute_fixup_cfg)
* tree-ssa-loop-ivcanon.cc (remove_exits_and_undefined_stmts)
(unloop_loops)
* tree-ssa-sccvn.cc (eliminate_dom_walker::eliminate_stmt):
Likewise.
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_builtin_function_call): Handle
unreachable/trap earlier.
* cp-gimplify.cc (cp_maybe_instrument_return): Use
build_builtin_unreachable.
gcc/testsuite/ChangeLog:
* g++.dg/ubsan/return-8a.C: New test.
* g++.dg/ubsan/return-8b.C: New test.
* g++.dg/ubsan/return-8d.C: New test.
* g++.dg/ubsan/return-8e.C: New test.
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