https://gcc.gnu.org/g:5c0e1879ea639dc527d3928af877d3df985e3f13
commit r15-7084-g5c0e1879ea639dc527d3928af877d3df985e3f13
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date: Mon Jan 20 22:09:22 2025 +1100
c++/modules: Handle mismatching TYPE_CANONICAL when deduping partial specs
[PR118101]
In r15-4862 we ensured that merging a partial specialisation would
properly update its TYPE_CANONICAL. However, this confuses the deduping
mechanism, since the canonical type has updated out from under it,
causing is_matching_decl to crash when seeing the equivalent types with
different TYPE_CANONICAL.
This patch solves the issue by forcing structural equality checking for
this case; this way mismatching TYPE_CANONICAL doesn't cause issues, but
we still can handle the case that the types are legitimately different.
PR c++/118101
gcc/cp/ChangeLog:
* module.cc (trees_in::decl_value): Use structural equality when
deduping partial specs with mismatching canonical types.
gcc/testsuite/ChangeLog:
* g++.dg/modules/partial-7.h: New test.
* g++.dg/modules/partial-7_a.C: New test.
* g++.dg/modules/partial-7_b.C: New test.
* g++.dg/modules/partial-7_c.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
Diff:
---
gcc/cp/module.cc | 11 ++++++++++-
gcc/testsuite/g++.dg/modules/partial-7.h | 5 +++++
gcc/testsuite/g++.dg/modules/partial-7_a.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/partial-7_b.C | 9 +++++++++
gcc/testsuite/g++.dg/modules/partial-7_c.C | 7 +++++++
5 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 6fe64bb538c2..813c14361417 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -8650,9 +8650,18 @@ trees_in::decl_value ()
if (stub_decl)
TREE_TYPE (stub_decl) = type;
+ tree etype = TREE_TYPE (existing);
+
/* Handle separate declarations with different attributes. */
- tree &eattr = TYPE_ATTRIBUTES (TREE_TYPE (existing));
+ tree &eattr = TYPE_ATTRIBUTES (etype);
eattr = merge_attributes (eattr, TYPE_ATTRIBUTES (type));
+
+ /* When merging a partial specialisation, the existing decl may have
+ had its TYPE_CANONICAL adjusted. If so we should use structural
+ equality to ensure is_matching_decl doesn't get confused. */
+ if ((spec_flags & 2)
+ && TYPE_CANONICAL (type) != TYPE_CANONICAL (etype))
+ SET_TYPE_STRUCTURAL_EQUALITY (type);
}
if (inner_tag)
diff --git a/gcc/testsuite/g++.dg/modules/partial-7.h
b/gcc/testsuite/g++.dg/modules/partial-7.h
new file mode 100644
index 000000000000..cf0411835a19
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/partial-7.h
@@ -0,0 +1,5 @@
+// PR c++/118101
+template <typename> struct A;
+template <typename T> struct A<T*> {};
+template <typename T> struct B { A<T*> f(); };
+B<int> inst();
diff --git a/gcc/testsuite/g++.dg/modules/partial-7_a.C
b/gcc/testsuite/g++.dg/modules/partial-7_a.C
new file mode 100644
index 000000000000..6aa7aeebfec3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/partial-7_a.C
@@ -0,0 +1,8 @@
+// PR c++/118101
+// { dg-additional-options "-fmodules" }
+// { dg-module-cmi A }
+
+module;
+#include "partial-7.h"
+export module A;
+B<int> a;
diff --git a/gcc/testsuite/g++.dg/modules/partial-7_b.C
b/gcc/testsuite/g++.dg/modules/partial-7_b.C
new file mode 100644
index 000000000000..1ca391a5ea15
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/partial-7_b.C
@@ -0,0 +1,9 @@
+// PR c++/118101
+// { dg-additional-options "-fmodules" }
+// { dg-module-cmi B }
+
+module;
+#include "partial-7.h"
+export module B;
+import A;
+B<int> b;
diff --git a/gcc/testsuite/g++.dg/modules/partial-7_c.C
b/gcc/testsuite/g++.dg/modules/partial-7_c.C
new file mode 100644
index 000000000000..3d2a2873e345
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/partial-7_c.C
@@ -0,0 +1,7 @@
+// PR c++/118101
+// { dg-additional-options "-fmodules" }
+
+template <typename> struct A {};
+template <typename T> struct B { A<T*> f(); };
+template struct B<int>;
+import B;
