diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/call.cc | 11 | ||||
| -rw-r--r-- | gcc/cp/class.cc | 8 | ||||
| -rw-r--r-- | gcc/cp/constexpr.cc | 166 | ||||
| -rw-r--r-- | gcc/cp/cp-tree.h | 1 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C | 2 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1y/constexpr-union6.C | 13 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1y/constexpr-union7.C | 18 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/constexpr-union2.C | 30 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/constexpr-union3.C | 45 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/constexpr-union4.C | 29 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/constexpr-union5.C | 80 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp2a/constexpr-union6.C | 53 |
12 files changed, 403 insertions, 53 deletions
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index e8dafbd..c1fb880 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -10330,10 +10330,7 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) && DECL_OVERLOADED_OPERATOR_IS (fn, NOP_EXPR) && trivial_fn_p (fn)) { - /* Don't use cp_build_fold_indirect_ref, op= returns an lvalue even if - the object argument isn't one. */ - tree to = cp_build_indirect_ref (input_location, argarray[0], - RO_ARROW, complain); + tree to = cp_build_fold_indirect_ref (argarray[0]); tree type = TREE_TYPE (to); tree as_base = CLASSTYPE_AS_BASE (type); tree arg = argarray[1]; @@ -10341,7 +10338,11 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) if (is_really_empty_class (type, /*ignore_vptr*/true)) { - /* Avoid copying empty classes. */ + /* Avoid copying empty classes, but ensure op= returns an lvalue even + if the object argument isn't one. This isn't needed in other cases + since MODIFY_EXPR is always considered an lvalue. */ + to = cp_build_addr_expr (to, tf_none); + to = cp_build_indirect_ref (input_location, to, RO_ARROW, complain); val = build2 (COMPOUND_EXPR, type, arg, to); suppress_warning (val, OPT_Wunused); } diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc index b71333a..e31aeb8 100644 --- a/gcc/cp/class.cc +++ b/gcc/cp/class.cc @@ -5688,6 +5688,14 @@ type_has_virtual_destructor (tree type) return (dtor && DECL_VIRTUAL_P (dtor)); } +/* True iff class TYPE has a non-deleted trivial default + constructor. */ + +bool type_has_non_deleted_trivial_default_ctor (tree type) +{ + return TYPE_HAS_TRIVIAL_DFLT (type) && locate_ctor (type); +} + /* Returns true iff T, a class, has a move-assignment or move-constructor. Does not lazily declare either. If USER_P is false, any move function will do. If it is true, the diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 1d59a2f..6e84c2d 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -3190,40 +3190,34 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t, cxx_set_object_constness (ctx, new_obj, /*readonly_p=*/false, non_constant_p, overflow_p); + /* If this is a constructor, we are beginning the lifetime of the + object we are initializing. */ + if (new_obj + && DECL_CONSTRUCTOR_P (fun) + && TREE_CODE (new_obj) == COMPONENT_REF + && TREE_CODE (TREE_TYPE (TREE_OPERAND (new_obj, 0))) == UNION_TYPE) + { + tree activate = build2 (INIT_EXPR, TREE_TYPE (new_obj), + new_obj, + build_constructor (TREE_TYPE (new_obj), + NULL)); + cxx_eval_constant_expression (ctx, activate, + lval, non_constant_p, overflow_p); + ggc_free (activate); + } + tree jump_target = NULL_TREE; cxx_eval_constant_expression (&call_ctx, body, vc_discard, non_constant_p, overflow_p, &jump_target); if (DECL_CONSTRUCTOR_P (fun)) - { - /* This can be null for a subobject constructor call, in - which case what we care about is the initialization - side-effects rather than the value. We could get at the - value by evaluating *this, but we don't bother; there's - no need to put such a call in the hash table. */ - result = lval ? ctx->object : ctx->ctor; - - /* If we've just evaluated a subobject constructor call for an - empty union member, it might not have produced a side effect - that actually activated the union member. So produce such a - side effect now to ensure the union appears initialized. */ - if (!result && new_obj - && TREE_CODE (new_obj) == COMPONENT_REF - && TREE_CODE (TREE_TYPE - (TREE_OPERAND (new_obj, 0))) == UNION_TYPE - && is_really_empty_class (TREE_TYPE (new_obj), - /*ignore_vptr*/false)) - { - tree activate = build2 (MODIFY_EXPR, TREE_TYPE (new_obj), - new_obj, - build_constructor (TREE_TYPE (new_obj), - NULL)); - cxx_eval_constant_expression (ctx, activate, lval, - non_constant_p, overflow_p); - ggc_free (activate); - } - } + /* This can be null for a subobject constructor call, in + which case what we care about is the initialization + side-effects rather than the value. We could get at the + value by evaluating *this, but we don't bother; there's + no need to put such a call in the hash table. */ + result = lval ? ctx->object : ctx->ctor; else if (VOID_TYPE_P (TREE_TYPE (res))) result = void_node; else @@ -4523,6 +4517,7 @@ cxx_eval_component_reference (const constexpr_ctx *ctx, tree t, *non_constant_p = true; return t; } + bool pmf = TYPE_PTRMEMFUNC_P (TREE_TYPE (whole)); FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value) { @@ -4541,21 +4536,36 @@ cxx_eval_component_reference (const constexpr_ctx *ctx, tree t, break; } } - if (TREE_CODE (TREE_TYPE (whole)) == UNION_TYPE - && CONSTRUCTOR_NELTS (whole) > 0) + if (TREE_CODE (TREE_TYPE (whole)) == UNION_TYPE) { - /* DR 1188 says we don't have to deal with this. */ - if (!ctx->quiet) + if (CONSTRUCTOR_NELTS (whole) > 0) { - constructor_elt *cep = CONSTRUCTOR_ELT (whole, 0); - if (cep->value == NULL_TREE) - error ("accessing uninitialized member %qD", part); - else - error ("accessing %qD member instead of initialized %qD member in " - "constant expression", part, cep->index); + /* DR 1188 says we don't have to deal with this. */ + if (!ctx->quiet) + { + constructor_elt *cep = CONSTRUCTOR_ELT (whole, 0); + if (cep->value == NULL_TREE) + error ("accessing uninitialized member %qD", part); + else + error ("accessing %qD member instead of initialized %qD member " + "in constant expression", part, cep->index); + } + *non_constant_p = true; + return t; + } + else if (!CONSTRUCTOR_NO_CLEARING (whole)) + { + /* Value-initialized union, check if looking at the first member. */ + tree first = next_aggregate_field (TYPE_FIELDS (TREE_TYPE (whole))); + if (first != part) + { + if (!ctx->quiet) + error ("accessing %qD member instead of initialized %qD " + "member in constant expression", part, first); + *non_constant_p = true; + return t; + } } - *non_constant_p = true; - return t; } /* We only create a CONSTRUCTOR for a subobject when we modify it, so empty @@ -6172,6 +6182,14 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, mutable_p) && const_object_being_modified == NULL_TREE) const_object_being_modified = probe; + + /* Track named member accesses for unions to validate modifications + that change active member. */ + if (!evaluated && TREE_CODE (probe) == COMPONENT_REF) + vec_safe_push (refs, probe); + else + vec_safe_push (refs, NULL_TREE); + vec_safe_push (refs, elt); vec_safe_push (refs, TREE_TYPE (probe)); probe = ob; @@ -6180,6 +6198,7 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, case REALPART_EXPR: gcc_assert (probe == target); + vec_safe_push (refs, NULL_TREE); vec_safe_push (refs, probe); vec_safe_push (refs, TREE_TYPE (probe)); probe = TREE_OPERAND (probe, 0); @@ -6187,6 +6206,7 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, case IMAGPART_EXPR: gcc_assert (probe == target); + vec_safe_push (refs, NULL_TREE); vec_safe_push (refs, probe); vec_safe_push (refs, TREE_TYPE (probe)); probe = TREE_OPERAND (probe, 0); @@ -6275,6 +6295,7 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, enum tree_code code = TREE_CODE (type); tree reftype = refs->pop(); tree index = refs->pop(); + bool is_access_expr = refs->pop() != NULL_TREE; if (code == COMPLEX_TYPE) { @@ -6313,23 +6334,73 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, break; } - type = reftype; + /* If a union is zero-initialized, its first non-static named data member + is zero-initialized (and therefore active). */ + if (code == UNION_TYPE + && !no_zero_init + && CONSTRUCTOR_NELTS (*valp) == 0) + if (tree first = next_aggregate_field (TYPE_FIELDS (type))) + CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (*valp), first, NULL_TREE); - if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp) - && CONSTRUCTOR_ELT (*valp, 0)->index != index) + /* Check for implicit change of active member for a union. */ + if (code == UNION_TYPE + && (CONSTRUCTOR_NELTS (*valp) == 0 + || CONSTRUCTOR_ELT (*valp, 0)->index != index) + /* An INIT_EXPR of the last member in an access chain is always OK, + but still check implicit change of members earlier on; see + cpp2a/constexpr-union6.C. */ + && !(TREE_CODE (t) == INIT_EXPR && refs->is_empty ())) { - if (cxx_dialect < cxx20) + bool has_active_member = CONSTRUCTOR_NELTS (*valp) != 0; + tree inner = strip_array_types (reftype); + + if (has_active_member && cxx_dialect < cxx20) { if (!ctx->quiet) error_at (cp_expr_loc_or_input_loc (t), "change of the active member of a union " - "from %qD to %qD", + "from %qD to %qD is not a constant expression " + "before C++20", CONSTRUCTOR_ELT (*valp, 0)->index, index); *non_constant_p = true; } - else if (TREE_CODE (t) == MODIFY_EXPR - && CONSTRUCTOR_NO_CLEARING (*valp)) + else if (!is_access_expr + || (TREE_CODE (t) == MODIFY_EXPR + && CLASS_TYPE_P (inner) + && !type_has_non_deleted_trivial_default_ctor (inner))) + { + /* Diagnose changing active union member after initialization + without a valid member access expression, as described in + [class.union.general] p5. */ + if (!ctx->quiet) + { + auto_diagnostic_group d; + if (has_active_member) + error_at (cp_expr_loc_or_input_loc (t), + "accessing %qD member instead of initialized " + "%qD member in constant expression", + index, CONSTRUCTOR_ELT (*valp, 0)->index); + else + error_at (cp_expr_loc_or_input_loc (t), + "accessing uninitialized member %qD", + index); + if (is_access_expr) + inform (DECL_SOURCE_LOCATION (index), + "%qD does not implicitly begin its lifetime " + "because %qT does not have a non-deleted " + "trivial default constructor, use " + "%<std::construct_at%> instead", + index, inner); + else + inform (DECL_SOURCE_LOCATION (index), + "initializing %qD requires a member access " + "expression as the left operand of the assignment", + index); + } + *non_constant_p = true; + } + else if (has_active_member && CONSTRUCTOR_NO_CLEARING (*valp)) { /* Diagnose changing the active union member while the union is in the process of being initialized. */ @@ -6355,6 +6426,7 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree t, activated_union_member_p = true; valp = &cep->value; + type = reftype; } /* For initialization of an empty base, the original target will be diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 1d7df62..8c75d03 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -6817,6 +6817,7 @@ extern bool trivial_default_constructor_is_constexpr (tree); extern bool type_has_constexpr_default_constructor (tree); extern bool type_has_constexpr_destructor (tree); extern bool type_has_virtual_destructor (tree); +extern bool type_has_non_deleted_trivial_default_ctor (tree); extern bool classtype_has_move_assign_or_move_ctor_p (tree, bool user_declared); extern bool classtype_has_non_deleted_move_ctor (tree); extern tree classtype_has_depr_implicit_copy (tree); diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C index 9d370dd..6a60966 100644 --- a/gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C +++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-89336-3.C @@ -18,7 +18,7 @@ constexpr int bar () { union U { int a[5]; long b; }; - union V { union U u; short v; }; + union V { short v; union U u; }; V w {}; w.v = 5; w.u.a[3] = w.u.a[1] = w.v; // { dg-error "change of the active member of a union from" "" { target c++17_down } } diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-union6.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-union6.C new file mode 100644 index 0000000..ff7ebf1 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-union6.C @@ -0,0 +1,13 @@ +// { dg-do compile { target c++14 } } + +union U { + int a; + float b; +}; + +constexpr bool foo() { + U u {}; + u.b = 1.0f; // { dg-error "change of the active member" "" { target c++17_down } } + return u.b == 1.0f; +} +constexpr bool x = foo(); diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-union7.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-union7.C new file mode 100644 index 0000000..6fc41f9 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-union7.C @@ -0,0 +1,18 @@ +// { dg-do compile { target c++14 } } + +// this type is not value-initialisable +struct S { const int a; int b; }; + +union U1 { int k; S s; }; +constexpr int test1() { + U1 u {}; + return u.s.b; // { dg-error "accessing .U1::s. member instead of initialized .U1::k. member" } +} +constexpr int x = test1(); + +union U2 { int :0; static int s; void foo(); int k; }; +constexpr int test2() { + U2 u {}; // should skip zero-width bitfields, static members, and functions + return u.k; +} +static_assert(test2() == 0, ""); diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-union2.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-union2.C new file mode 100644 index 0000000..1712395 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-union2.C @@ -0,0 +1,30 @@ +// PR c++/101631 +// { dg-do compile { target c++20 } } + +struct sso { + union { + int buf[10]; + int* alloc; + }; +}; + +constexpr bool direct() { + sso val; + val.alloc = nullptr; + val.buf[5] = 42; + return true; +} +constexpr bool ok = direct(); + + +constexpr void perform_assignment(int& left, int right) noexcept { + left = right; // { dg-error "accessing .+ member instead of initialized" } +} + +constexpr bool indirect() { + sso val; + val.alloc = nullptr; + perform_assignment(val.buf[5], 42); // { dg-message "in .constexpr. expansion" } + return true; +} +constexpr bool err = indirect(); // { dg-message "in .constexpr. expansion" } diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-union3.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-union3.C new file mode 100644 index 0000000..6d30bb2 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-union3.C @@ -0,0 +1,45 @@ +// { dg-do compile { target c++20 } } + +struct S +{ + union { + char buf[8]; + char* ptr; + }; + unsigned len; + + constexpr S(const char* s, unsigned n) + { + char* p; + if (n > 7) + p = ptr = new char[n+1]; + else + p = buf; + for (len = 0; len < n; ++len) + p[len] = s[len]; // { dg-error "accessing uninitialized member" } + p[len] = '\0'; + } + + constexpr ~S() + { + if (len > 7) + delete[] ptr; + } +}; + +constexpr bool test1() +{ + S s("test", 4); // { dg-message "in .constexpr. expansion" } + return true; +} + +constexpr bool a = test1(); // { dg-message "in .constexpr. expansion" } + + +constexpr bool test2() +{ + S s("hello world", 11); + return true; +} + +constexpr bool b = test2(); diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-union4.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-union4.C new file mode 100644 index 0000000..429ab20 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-union4.C @@ -0,0 +1,29 @@ +// { dg-do compile { target c++20 } } + +// from [class.union.general] p5 + +union A { int x; int y[4]; }; +struct B { A a; }; +union C { B b; int k; }; +constexpr int f() { + C c; // does not start lifetime of any union member + c.b.a.y[3] = 4; // OK, S(c.b.a.y[3]) contains c.b and c.b.a.y; + // creates objects to hold union members c.b and c.b.a.y + return c.b.a.y[3]; // OK, c.b.a.y refers to newly created object (see [basic.life]) +} +constexpr int a = f(); + +struct X { const int a; int b; }; +union Y { X x; int k; };// { dg-message "does not implicitly begin its lifetime" } +constexpr int g() { + Y y = { { 1, 2 } }; // OK, y.x is active union member ([class.mem]) + int n = y.x.a; + y.k = 4; // OK, ends lifetime of y.x, y.k is active member of union + + y.x.b = n; // { dg-error "accessing .* member instead of initialized .* member" } + // undefined behavior: y.x.b modified outside its lifetime, + // S(y.x.b) is empty because X's default constructor is deleted, + // so union member y.x's lifetime does not implicitly start + return 0; +} +constexpr int b = g(); // { dg-message "in .constexpr. expansion" } diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-union5.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-union5.C new file mode 100644 index 0000000..7e42522 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-union5.C @@ -0,0 +1,80 @@ +// { dg-do compile { target c++20 } } + +union U { int a; int b; int c[2]; }; + +constexpr int test1() { + U u; + u.a = 10; + *&u.b = 20; // { dg-error "accessing" } + return u.b; +} +constexpr int x1 = test1(); // { dg-message "in .constexpr. expansion" } + +constexpr int test2() { + U u; + u.a = 10; + (0, u.b) = 20; // { dg-error "accessing" } + return u.b; +} +constexpr int x2 = test2(); // { dg-message "in .constexpr. expansion" } + +constexpr int test3() { + U u; + u.a = 0; + int* p = &u.b; + p[u.a] = 10; // { dg-error "accessing" } + return u.b; +} +constexpr int x3 = test3(); // { dg-message "in .constexpr. expansion" } + +constexpr int test4() { + U u; + u.a = 0; + int* p = &u.b; + u.a[p] = 10; // { dg-error "accessing" } + return u.b; +} +constexpr int x4 = test4(); // { dg-message "in .constexpr. expansion" } + +struct S { U u[10]; }; +constexpr int test5() { + S s; + s.u[4].a = 10; + 6[s.u].b = 15; + return 4[s.u].a + s.u[6].b; +} +static_assert(test5() == 25); + +constexpr int test6() { + U u; + u.a = 5; + u.c[0] = 3; + 1[u.c] = 8; + return 1[u.c] + u.c[0]; +} +static_assert(test6() == 11); + +constexpr int test7() { + U u; // default initialisation leaves no member initialised + int* p = &u.a; + *p = 10; // { dg-error "accessing" } + return *p; +} +constexpr int x7 = test7(); // { dg-message "in .constexpr. expansion" } + +constexpr int test8() { + U u {}; // value initialisation initialises first member + int* p = &u.a; + *p = 8; + return *p; +} +static_assert(test8() == 8); + +union V { int :0; static int x; void foo(); int a; }; +constexpr int test9() { + V v {}; // should skip zero-width bit fields, static members, and functions + int* p = &v.a; + *p = 9; + return *p; +} +static_assert(test9() == 9); diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-union6.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-union6.C new file mode 100644 index 0000000..00bda53 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-union6.C @@ -0,0 +1,53 @@ +// { dg-do compile { target c++20 } } +// PR c++/102286 + +#include "construct_at.h" + +struct S { const int a; int b; }; +union U { int k; S s; }; + +constexpr int test1() { + U u {}; + std::construct_at(&u.s, S{ 1, 2 }); + return u.s.b; +} +static_assert(test1() == 2); + +constexpr int test2() { + U u {}; + int* p = &u.s.b; + std::construct_at(p, 5); // { dg-message "in .constexpr. expansion" } + return u.s.b; +} +constexpr int x2 = test2(); // { dg-message "in .constexpr. expansion" } + +constexpr void foo(S* s) { + s->b = 10; // { dg-error "accessing .U::s. member instead of initialized .U::k." } +} +constexpr int test3() { + U u {}; + foo(&u.s); // { dg-message "in .constexpr. expansion" } + return u.s.b; +} +constexpr int x3 = test3(); // { dg-message "in .constexpr. expansion" } + +struct S2 { int a; int b; }; +union U2 { int k; S2 s; }; +constexpr int test4() { + U2 u; + int* p = &u.s.b; + std::construct_at(p, 8); // { dg-message "in .constexpr. expansion" } + return u.s.b; +}; +constexpr int x4 = test4(); // { dg-message "in .constexpr. expansion" } + +constexpr int test5() { + union { + int data[1]; + } u; + std::construct_at(u.data, 0); // { dg-message "in .constexpr. expansion" } + return 0; +} +constexpr int x5 = test5(); // { dg-message "in .constexpr. expansion" } + +// { dg-error "accessing (uninitialized member|.* member instead of)" "" { target *-*-* } 0 } |