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| author | Jason Merrill <jason@redhat.com> | 2021-11-05 00:08:53 -0400 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2021-11-15 02:45:48 -0500 |
| commit | 4df7f8c79835d56928f51f9e674d326300936e8e (patch) | |
| tree | 7e18a7d480f0c30b44494ef0f15f38e108fc2b11 /gcc | |
| parent | 267318a2857a42922c3ca033dac4690172b17683 (diff) | |
| download | gcc-4df7f8c79835d56928f51f9e674d326300936e8e.zip gcc-4df7f8c79835d56928f51f9e674d326300936e8e.tar.gz gcc-4df7f8c79835d56928f51f9e674d326300936e8e.tar.bz2 | |
c++: don't do constexpr folding in unevaluated context
The implicit constexpr patch revealed that we were doing constant evaluation
of arbitrary expressions in unevaluated contexts, leading to failure when we
tried to evaluate e.g. a call to declval. This is wrong more generally;
only manifestly-constant-evaluated expressions should be evaluated within
an unevaluated operand.
Making this change revealed a case we were failing to mark as manifestly
constant-evaluated.
gcc/cp/ChangeLog:
* constexpr.c (maybe_constant_value): Don't evaluate
in an unevaluated operand unless manifestly const-evaluated.
(fold_non_dependent_expr_template): Likewise.
* decl.c (compute_array_index_type_loc): This context is
manifestly constant-evaluated.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/cp/constexpr.c | 7 | ||||
| -rw-r--r-- | gcc/cp/decl.c | 2 |
2 files changed, 8 insertions, 1 deletions
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index 7c27131..82a597d 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7696,6 +7696,10 @@ maybe_constant_value (tree t, tree decl, bool manifestly_const_eval) return r; } + /* Don't evaluate an unevaluated operand. */ + if (cp_unevaluated_operand) + return t; + uid_sensitive_constexpr_evaluation_checker c; r = cxx_eval_outermost_constant_expr (t, true, true, false, false, decl); gcc_checking_assert (r == t @@ -7759,6 +7763,9 @@ fold_non_dependent_expr_template (tree t, tsubst_flags_t complain, return t; } + if (cp_unevaluated_operand && !manifestly_const_eval) + return t; + tree r = cxx_eval_outermost_constant_expr (t, true, true, manifestly_const_eval, false, object); diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 947bbfc..eed4781 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -11000,7 +11000,7 @@ compute_array_index_type_loc (location_t name_loc, tree name, tree size, cp_convert (ssizetype, integer_one_node, complain), complain); - itype = maybe_constant_value (itype); + itype = maybe_constant_value (itype, NULL_TREE, true); } if (!TREE_CONSTANT (itype)) |