From: Patrick Palka <ppalka@redhat.com>
Date: Fri, 8 Jan 2021 15:11:25 +0000 (-0500)
Subject: c++: ICE with constexpr call that returns a PMF [PR98551]
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=bb1f0b50abbfa01e0ed720a5225a11aa7af32a89;p=gcc.git

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

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.
---

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 4a5e6384da6..9dddc53ca52 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -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;
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-pmf2.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-pmf2.C
new file mode 100644
index 00000000000..a76e712afe1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-pmf2.C
@@ -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());