[clang] f82df0b - [C++20] [Modules] Use CanonicalType for base classes

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2023-07-11T15:59:03+08:00
New Revision: f82df0b285acd8a7115f0bfc55ce44474251c2d1

URL: https://github.com/llvm/llvm-project/commit/f82df0b285acd8a7115f0bfc55ce44474251c2d1
DIFF: https://github.com/llvm/llvm-project/commit/f82df0b285acd8a7115f0bfc55ce44474251c2d1.diff

LOG: [C++20] [Modules] Use CanonicalType for base classes

This comes from https://reviews.llvm.org/D153003

By @rsmith, the test case is valid since:

> Per [temp.type]/1.4 (http://eel.is/c++draft/temp.type#1.4),
>
>> Two template-ids are the same if [...] their corresponding template
>> template-arguments refer to the same template.
> so B<A> and B<NS::A> are the same type. The stricter "same sequence of
> tokens" rule doesn't apply here, because using-declarations are not
> definitions.

> we should either (preferably) be including only the syntactic form of
> the base specifier (because local syntax is what the ODR covers), or
> the canonical type (which should be the same for both
> using-declarations).

Here we adopt the second suggested solutions.

Reviewed By: cor3ntin, v.g.vassilev

Differential Revision: https://reviews.llvm.org/D154324

Added: 
    clang/test/Modules/pr63595.cppm

Modified: 
    clang/lib/AST/ODRHash.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/ODRHash.cpp b/clang/lib/AST/ODRHash.cpp
index 507fb0b49f8ad3..40d68a310dd2a8 100644
--- a/clang/lib/AST/ODRHash.cpp
+++ b/clang/lib/AST/ODRHash.cpp
@@ -593,7 +593,7 @@ void ODRHash::AddCXXRecordDecl(const CXXRecordDecl *Record) {
   ID.AddInteger(Record->getNumBases());
   auto Bases = Record->bases();
   for (const auto &Base : Bases) {
-    AddQualType(Base.getType());
+    AddQualType(Base.getType().getCanonicalType());
     ID.AddInteger(Base.isVirtual());
     ID.AddInteger(Base.getAccessSpecifierAsWritten());
   }

diff  --git a/clang/test/Modules/pr63595.cppm b/clang/test/Modules/pr63595.cppm
new file mode 100644
index 00000000000000..f2caf629ac10b8
--- /dev/null
+++ b/clang/test/Modules/pr63595.cppm
@@ -0,0 +1,44 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface -I%t %t/module1.cppm -o %t/module1.pcm
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface -I%t %t/module2.cppm -o %t/module2.pcm
+// RUN: %clang_cc1 -std=c++20 -fprebuilt-module-path=%t %t/merge.cpp -verify -fsyntax-only
+
+//--- header.h
+namespace NS {
+template <int I>
+class A {
+};
+
+template <template <int I_> class T>
+class B {
+};
+}
+
+//--- module1.cppm
+// inside NS, using C = B<A>
+module;
+export module module1;
+#include "header.h"
+namespace NS {
+using C = B<A>;
+}
+export struct D : NS::C {};
+
+//--- module2.cppm
+// inside NS, using C = B<NS::A>
+module;
+export module module2;
+#include "header.h"
+namespace NS {
+using C = B<NS::A>;
+}
+export struct D : NS::C {};
+
+//--- merge.cpp
+// expected-no-diagnostics
+import module1;
+import module2;
+D d;