[NFC] [clang] add tests for merging of UsingShadowDecl

Author: mizvekov

clang/test/Modules/GH80252.cppm

@@ -0,0 +1,42 @@
+// 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.cppm -emit-module-interface -o %t/B.pcm -verify
+// RUN: %clang_cc1 -std=c++20 -I %t %t/C.cpp -fmodule-file=A=%t/A.pcm -fmodule-file=B=%t/B.pcm -fsyntax-only -verify
+
+//--- foo.h
+namespace baz {
+  using foo = char;
+  using baz::foo;
+}
+
+//--- bar.h
+class bar {
+  bar(baz::foo);
+};
+
+//--- A.cppm
+// expected-no-diagnostics
+module;
+#include "foo.h"
+export module A;
+
+//--- B.cppm
+// expected-no-diagnostics
+module;
+#include "foo.h"
+#include "bar.h"
+export module B;
+
+//--- C.cpp
+#include "foo.h"
+import A;
+#include "bar.h"
+import B;
+// Since modules are loaded lazily, force loading by performing a lookup.
+using xxx = bar;
+// FIXME: This is a false positive ODR violation.
+// [email protected]:2 {{'bar' has different definitions in different modules; first difference is defined here found constructor with 1st parameter of type 'baz::foo' (aka 'char')}}
+// [email protected]:2 {{but in 'B.<global>' found constructor with 1st parameter of type 'baz::foo' (aka 'char')}}

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'