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authorJakub Jelinek <jakub@redhat.com>2021-02-18 16:21:52 +0100
committerJakub Jelinek <jakub@redhat.com>2021-02-18 16:21:52 +0100
commit3bfa96895b3219afd93a7038850baef4b63c1f82 (patch)
treedb0554af17b92c82762da9c050e3df83db7c429c
parent7ee164dcfe390fc030028db9112d44255637b1aa (diff)
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c++: Fix -std=c++20 ICE on virtual method call [PR99132]
On the following testcase we ICE in C++20 mode during cp_get_callee_fndecl -> constexpr evaluation. It is only in C++20 mode on this testcase because virtual methods can't be constexpr in C++17 and earlier and so potential_constant_expression_1 rejects it earlier. And the ICE is caused by genericization changing the h PARM_DECL from having B<C *> type to B<C *> & DECL_BY_REFERENCE and the constexpr evaluation not being able to deal with that. I think this just shows that we shouldn't do the constexpr evaluation during genericization and later, and other spots e.g. during gimplification also don't call cp_get_callee_fndecl but cp_get_callee_fndecl_nofold. After all, cp_fold has already been run and it did the folding if there was any opportunity to do so. And furthermore, what that cp_genericize_r spot does is check for any left-over immediate function calls (which can be ATM just std::source_location::current() call) and immediate functions outside of immediate functions can't have addresses leaked into the IL, so it will be always a direct call anyway. And immediate functions themselves don't make it into genericization/gimplification. 2021-02-18 Jakub Jelinek <jakub@redhat.com> PR c++/99132 * cp-gimplify.c (cp_genericize_r) <case CALL_EXPR>: Use cp_get_callee_fndecl_nofold instead of cp_get_callee_fndecl to check for immediate function calls. * g++.dg/cpp2a/constexpr-virtual18.C: New test.
-rw-r--r--gcc/cp/cp-gimplify.c2
-rw-r--r--gcc/testsuite/g++.dg/cpp2a/constexpr-virtual18.C13
2 files changed, 14 insertions, 1 deletions
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index 1c5e15b..abb8a6e 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -1386,7 +1386,7 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
break;
}
- if (tree fndecl = cp_get_callee_fndecl (stmt))
+ if (tree fndecl = cp_get_callee_fndecl_nofold (stmt))
if (DECL_IMMEDIATE_FUNCTION_P (fndecl))
{
gcc_assert (source_location_current_p (fndecl));
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-virtual18.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-virtual18.C
new file mode 100644
index 0000000..2fbf0b2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-virtual18.C
@@ -0,0 +1,13 @@
+// PR c++/99132
+// { dg-do compile { target c++11 } }
+
+template <class T> struct A { T c; };
+template <class T> struct B {
+ A<T> d;
+ constexpr T operator-> () { return d.c; }
+ B (B &&);
+};
+struct C {
+ virtual void foo ();
+ void bar (B<C *> h) { h->foo (); }
+};