From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 6 May 2020 21:36:31 +0000 (+0200)
Subject: c++: Don't synthesize sfk_comparison method multiple times [PR94907]
X-Git-Tag: misc/first-auto-changelog-10~71
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3d4c7e05de438fb0672f376e628c18812eea8982;p=thirdparty%2Fgcc.git

c++: Don't synthesize sfk_comparison method multiple times [PR94907]

On the following testcase we ICE, because synthesize_method is called twice
on the same sfk_comparison method fndecl, the first time it works fine
because start_preparsed_function in that case sets both
current_function_decl and cfun, but second time it is called it only sets
the former and keeps cfun NULL, so we ICE when trying to store
current_function_returns_value.
I think it is just wrong to call synthesize_method multiple times, and most
synthesize_method callers avoid that by not calling it if DECL_INITIAL is
already set, so this patch does that too.

2020-05-06  Jakub Jelinek  <jakub@redhat.com>

	PR c++/94907
	* method.c (defaulted_late_check): Don't call synthesize_method
	on constexpr sfk_comparison if it has been called on it already.

	* g++.dg/cpp2a/spaceship-synth8.C: New test.
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e99485b12db4..f32ef9239c7b 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/94907
+	* method.c (defaulted_late_check): Don't call synthesize_method
+	on constexpr sfk_comparison if it has been called on it already.
+
 2020-05-07  Release Manager
 
 	* GCC 10.1.0 released.
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index fb2dd47013f4..47f96aa845ec 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -2939,7 +2939,7 @@ defaulted_late_check (tree fn)
     {
       /* If the function was declared constexpr, check that the definition
 	 qualifies.  Otherwise we can define the function lazily.  */
-      if (DECL_DECLARED_CONSTEXPR_P (fn))
+      if (DECL_DECLARED_CONSTEXPR_P (fn) && !DECL_INITIAL (fn))
 	synthesize_method (fn);
       return;
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0bc4058d318f..28faf7a9b563 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/94907
+	* g++.dg/cpp2a/spaceship-synth8.C: New test.
+
 2020-05-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/94873
diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8.C
new file mode 100644
index 000000000000..d0d68c7fa6fe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-synth8.C
@@ -0,0 +1,12 @@
+// PR c++/94907
+// { dg-do compile { target c++2a } }
+
+namespace std { struct strong_ordering { }; }
+
+struct E;
+struct D {
+  virtual std::strong_ordering operator<=>(const struct E&) const = 0;
+};
+struct E : D {
+  std::strong_ordering operator<=>(const E&) const override = default;
+};