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c++: ICE with constexpr call that returns a PMF [PR98551]

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We shouldn't do replace_result_decl after evaluating a call that returns
a PMF because PMF temporaries aren't wrapped in a TARGET_EXPR (and so we
can't trust ctx->object), and PMF initializers can't be self-referential
anyway, so replace_result_decl would always be a no-op.

To that end, this patch changes the relevant AGGREGATE_TYPE_P test to
CLASS_TYPE_P, which should rule out PMFs (as well as arrays, which we
can't return and therefore won't see here).  This fixes an ICE from the
sanity check in replace_result_decl in the below testcase during
constexpr evaluation of the call f() in the initializer g(f()).

gcc/cp/ChangeLog:

	PR c++/98551
	* constexpr.c (cxx_eval_call_expression): Check CLASS_TYPE_P
	instead of AGGREGATE_TYPE_P before calling replace_result_decl.

gcc/testsuite/ChangeLog:

	PR c++/98551
	* g++.dg/cpp0x/constexpr-pmf2.C: New test.
This commit is contained in:
Patrick Palka 2021-01-08 10:11:25 -05:00
parent 98a1fb705e
commit bb1f0b50ab
2 changed files with 10 additions and 1 deletions
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2
gcc/cp/constexpr.c
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@ -2790,7 +2790,7 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
/* Rewrite all occurrences of the function's RESULT_DECL with the
current object under construction. */
if (!*non_constant_p && ctx->object
&& AGGREGATE_TYPE_P (TREE_TYPE (res))
&& CLASS_TYPE_P (TREE_TYPE (res))
&& !is_empty_class (TREE_TYPE (res)))
if (replace_result_decl (&result, res, ctx->object))
cacheable = false;

9
gcc/testsuite/g++.dg/cpp0x/constexpr-pmf2.C Normal file
View File

@ -0,0 +1,9 @@
// PR c++/98551
// { dg-do compile { target c++11 } }
struct A {};
struct B { int t(); };
using pmf = decltype(&B::t);
constexpr pmf f() { return &B::t; }
constexpr A g(pmf) { return {}; };
constexpr A x = g(f());