[clang] Users/mizvekov/bug/clang merge usingshadowdecl (PR #80245)
Matheus Izvekov via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 31 21:57:18 PST 2024
https://github.com/mizvekov created https://github.com/llvm/llvm-project/pull/80245
[clang] fix merging of UsingShadowDecl
Previously, when deciding if two UsingShadowDecls where mergeable,
we would incorrectly only look for both pointing to the exact redecla
ration, whereas the correct thing is to look for declarations to the
same entity.
This problem has existed as far back as 2013, introduced in commit fd8634a09de71.
This problem could manifest itself as ODR check false positives when importing modules.
Fixes: #ISSUE_TO_BE_CREATED
>From 23a0d731cfe8593c338fc8ad7920f7aa9270afaa Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov at gmail.com>
Date: Thu, 1 Feb 2024 02:07:16 -0300
Subject: [PATCH 1/2] [NFC] [clang] add test for merging of UsingShadowDecl
---
clang/test/Modules/cxx20-decls.cppm | 44 +++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
create mode 100644 clang/test/Modules/cxx20-decls.cppm
diff --git a/clang/test/Modules/cxx20-decls.cppm b/clang/test/Modules/cxx20-decls.cppm
new file mode 100644
index 0000000000000..052c8e73be247
--- /dev/null
+++ b/clang/test/Modules/cxx20-decls.cppm
@@ -0,0 +1,44 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: %clang_cc1 -std=c++20 -I %t %t/A.cppm -emit-module-interface -o %t/A.pcm -verify
+// RUN: %clang_cc1 -std=c++20 -I %t %t/B.cpp -fmodule-file=A=%t/A.pcm -fsyntax-only -verify -ast-dump-all -ast-dump-filter baz | FileCheck %s
+
+//--- foo.h
+namespace baz {
+ using foo = char;
+ using baz::foo;
+}
+
+//--- A.cppm
+// expected-no-diagnostics
+module;
+#include "foo.h"
+export module A;
+
+//--- B.cpp
+// expected-no-diagnostics
+#include "foo.h"
+import A;
+// Since modules are loaded lazily, force loading by performing a lookup.
+using xxx = baz::foo;
+
+// CHECK-LABEL: Dumping baz:
+// CHECK-NEXT: NamespaceDecl 0x[[BAZ_REDECL_ADDR:[^ ]*]] prev 0x[[BAZ_ADDR:[^ ]*]] <{{.*}}> line:{{.*}} imported in A.<global> hidden <undeserialized declarations> baz
+// CHECK-NEXT: |-original Namespace 0x[[BAZ_ADDR]] 'baz'
+// CHECK-NEXT: |-TypeAliasDecl 0x[[ALIAS_REDECL_ADDR:[^ ]*]] prev 0x[[ALIAS_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} imported in A.<global> hidden foo 'char'
+// CHECK-NEXT: | `-BuiltinType 0x{{[^ ]*}} 'char'
+// CHECK-NEXT: |-UsingDecl 0x{{[^ ]*}} first 0x[[USING_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} imported in A.<global> hidden baz::foo
+// CHECK-NEXT: | `-NestedNameSpecifier Namespace 0x[[BAZ_REDECL_ADDR]] 'baz'
+// FIXME: UsingShadowDecl should have been merged
+// CHECK-NOT: `-UsingShadowDecl 0x{{[^ ]*}} prev 0x{{[^ ]*}} <{{.*}}> col:{{.*}} imported in A.<global> hidden implicit TypeAlias 0x[[ALIAS_REDECL_ADDR]] 'foo'
+// CHECK-NEXT: `-UsingShadowDecl 0x{{[^ ]*}} <{{.*}}> col:{{.*}} imported in A.<global> hidden implicit TypeAlias 0x[[ALIAS_REDECL_ADDR]] 'foo'
+
+// CHECK-LABEL: Dumping baz:
+// CHECK-NEXT: NamespaceDecl 0x[[BAZ_ADDR]] <{{.*}}> line:{{.*}} baz
+// CHECK-NEXT: |-TypeAliasDecl 0x[[ALIAS_ADDR]] <{{.*}}> col:{{.*}} referenced foo 'char'
+// CHECK-NEXT: | `-BuiltinType 0x{{[^ ]*}} 'char'
+// CHECK-NEXT: |-UsingDecl 0x[[USING_ADDR]] <{{.*}}> col:{{.*}} baz::foo
+// CHECK-NEXT: | `-NestedNameSpecifier Namespace 0x[[BAZ_ADDR]] 'baz'
+// CHECK-NEXT: `-UsingShadowDecl 0x[[SHADOW_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} implicit TypeAlias 0x[[ALIAS_ADDR]] 'foo'
>From b44f1b2ee3d709c627c1679fe3a252ea564bdd3d Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov at gmail.com>
Date: Thu, 1 Feb 2024 02:26:10 -0300
Subject: [PATCH 2/2] [clang] fix merging of UsingShadowDecl
Previously, when deciding if two UsingShadowDecls where mergeable,
we would incorrectly only look for both pointing to the exact redecla
ration, whereas the correct thing is to look for declarations to the
same entity.
This problem has existed as far back as 2013, introduced in commit
fd8634a09de71.
This problem could manifest itself as ODR check false positives
when importing modules.
Fixes: #ISSUE_TO_BE_CREATED
---
clang/docs/ReleaseNotes.rst | 3 +++
clang/lib/AST/ASTContext.cpp | 2 +-
clang/test/Modules/cxx20-decls.cppm | 6 ++----
3 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b7b11ab3a6b2e..aa14b8e931101 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -181,6 +181,9 @@ Bug Fixes to C++ Support
and (`#79745 <https://github.com/llvm/llvm-project/issues/79745>`_)
- Fix incorrect code generation caused by the object argument of ``static operator()`` and ``static operator[]`` calls not being evaluated.
Fixes (`#67976 <https://github.com/llvm/llvm-project/issues/67976>`_)
+- Fix incorrect merging of modules which contain using declarations which shadow
+ other declarations. This could manifest as ODR checker false positives.
+ Fixes (`#TODO <https://github.com/llvm/llvm-project/issues/TODO>`_)
Bug Fixes to AST Handling
^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 71c9c0003d18c..feeb350bf3e0c 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -6732,7 +6732,7 @@ bool ASTContext::isSameEntity(const NamedDecl *X, const NamedDecl *Y) const {
// Using shadow declarations with the same target match.
if (const auto *USX = dyn_cast<UsingShadowDecl>(X)) {
const auto *USY = cast<UsingShadowDecl>(Y);
- return USX->getTargetDecl() == USY->getTargetDecl();
+ return declaresSameEntity(USX->getTargetDecl(), USY->getTargetDecl());
}
// Using declarations with the same qualifier match. (We already know that
diff --git a/clang/test/Modules/cxx20-decls.cppm b/clang/test/Modules/cxx20-decls.cppm
index 052c8e73be247..ee9f117278884 100644
--- a/clang/test/Modules/cxx20-decls.cppm
+++ b/clang/test/Modules/cxx20-decls.cppm
@@ -31,9 +31,7 @@ using xxx = baz::foo;
// CHECK-NEXT: | `-BuiltinType 0x{{[^ ]*}} 'char'
// CHECK-NEXT: |-UsingDecl 0x{{[^ ]*}} first 0x[[USING_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} imported in A.<global> hidden baz::foo
// CHECK-NEXT: | `-NestedNameSpecifier Namespace 0x[[BAZ_REDECL_ADDR]] 'baz'
-// FIXME: UsingShadowDecl should have been merged
-// CHECK-NOT: `-UsingShadowDecl 0x{{[^ ]*}} prev 0x{{[^ ]*}} <{{.*}}> col:{{.*}} imported in A.<global> hidden implicit TypeAlias 0x[[ALIAS_REDECL_ADDR]] 'foo'
-// CHECK-NEXT: `-UsingShadowDecl 0x{{[^ ]*}} <{{.*}}> col:{{.*}} imported in A.<global> hidden implicit TypeAlias 0x[[ALIAS_REDECL_ADDR]] 'foo'
+// CHECK-NEXT: `-UsingShadowDecl 0x{{[^ ]*}} prev 0x[[SHADOW_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} imported in A.<global> hidden implicit TypeAlias 0x[[ALIAS_REDECL_ADDR]] 'foo'
// CHECK-LABEL: Dumping baz:
// CHECK-NEXT: NamespaceDecl 0x[[BAZ_ADDR]] <{{.*}}> line:{{.*}} baz
@@ -41,4 +39,4 @@ using xxx = baz::foo;
// CHECK-NEXT: | `-BuiltinType 0x{{[^ ]*}} 'char'
// CHECK-NEXT: |-UsingDecl 0x[[USING_ADDR]] <{{.*}}> col:{{.*}} baz::foo
// CHECK-NEXT: | `-NestedNameSpecifier Namespace 0x[[BAZ_ADDR]] 'baz'
-// CHECK-NEXT: `-UsingShadowDecl 0x[[SHADOW_ADDR:[^ ]*]] <{{.*}}> col:{{.*}} implicit TypeAlias 0x[[ALIAS_ADDR]] 'foo'
+// CHECK-NEXT: `-UsingShadowDecl 0x[[SHADOW_ADDR]] <{{.*}}> col:{{.*}} implicit TypeAlias 0x[[ALIAS_ADDR]] 'foo'
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