Hi!
On the following testcase we ICE, because expand_or_defer_fn is called
multiple times on the same ctor (once from instantiation of constexpr
functions, once from c_parse_final_cleanups) and this calls maybe_clone_body
which isn't really prepared to be called multiple times. In particular,
when the clones already have DECL_INITIAL etc., calling
start_preparsed_function on it again doesn't set cfun to non-NULL and the
code wants to store something there (but generally, it is pointless to do it
again even if it worked). If maybe_clone_body returns true, we set
TREE_ASM_WRITTEN:
if (maybe_clone_body (fn))
{
/* We don't want to process FN again, so pretend we've written
it out, even though we haven't. */
TREE_ASM_WRITTEN (fn) = 1;
/* If this is a constexpr function, keep DECL_SAVED_TREE. */
if (!DECL_DECLARED_CONSTEXPR_P (fn))
DECL_SAVED_TREE (fn) = NULL_TREE;
return false;
}
but if it doesn't because it wants to emit the original ctor as well (can't
use aliases), then we don't set that. This patch moves the -fsyntax-only
setting of the TREE_ASM_WRITTEN bit from c_parse_final_cleanups to
expand_or_defer_fn_1, so that if we do it once, we don't do that again.
For -fsyntax-only, I believe there is nothing further we want to do on the
cdtor.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2019-02-20 Jakub Jelinek <ja...@redhat.com>
PR c++/89403
* decl2.c (c_parse_final_cleanups): Move TREE_ASM_WRITTEN setting
for flag_syntax_only from here...
* semantics.c (expand_or_defer_fn_1): ... here.
* g++.dg/cpp0x/pr89403.C: New test.
--- gcc/cp/decl2.c.jj 2019-01-25 23:46:07.045183165 +0100
+++ gcc/cp/decl2.c 2019-02-20 18:37:36.824869503 +0100
@@ -4965,11 +4965,6 @@ c_parse_final_cleanups (void)
/* Generate RTL for this function now that we know we
need it. */
expand_or_defer_fn (decl);
- /* If we're compiling -fsyntax-only pretend that this
- function has been written out so that we don't try to
- expand it again. */
- if (flag_syntax_only)
- TREE_ASM_WRITTEN (decl) = 1;
reconsider = true;
}
}
--- gcc/cp/semantics.c.jj 2019-02-18 20:48:37.667649895 +0100
+++ gcc/cp/semantics.c 2019-02-20 18:45:00.582682109 +0100
@@ -4352,7 +4352,12 @@ expand_or_defer_fn_1 (tree fn)
/* There's no reason to do any of the work here if we're only doing
semantic analysis; this code just generates RTL. */
if (flag_syntax_only)
- return false;
+ {
+ /* Pretend that this function has been written out so that we don't try
+ to expand it again. */
+ TREE_ASM_WRITTEN (fn) = 1;
+ return false;
+ }
return true;
}
--- gcc/testsuite/g++.dg/cpp0x/pr89403.C.jj 2019-02-20 18:41:01.007535052
+0100
+++ gcc/testsuite/g++.dg/cpp0x/pr89403.C 2019-02-20 18:40:05.687424739
+0100
@@ -0,0 +1,18 @@
+// PR c++/89403
+// { dg-do compile { target c++11 } }
+// { dg-options "-Os -fsyntax-only" }
+
+template <typename T>
+struct A : T {
+ constexpr A() : T() { }
+};
+
+template <typename T>
+struct B {
+ A<T> b;
+ constexpr B() { }
+};
+
+struct C { struct {} s; };
+constexpr B<C> b{};
+constexpr C c = b.b;
Jakub
