[clang] Ignore inline namespace for hasName (#109147)

Add a new enumeration `SuppressInlineNamespaceMode` to `PrintingPolicy` that
is explicit about how to handle inline namespaces. `SuppressInlineNamespace`
uses that enumeration now instead of a Boolean value.

Specializing a template from an inline namespace should be transparent.
For instance

```
namespace foo {
    inline namespace v1 {
        template<typename A>
        void function(A&);
    }
}

namespace foo {
    template<>
    void function<int>(int&);
}
```

`hasName` should match both declarations of `foo::function`.

Makes the behavior of `matchesNodeFullSlow` and `matchesNodeFullFast`
consistent, fixing an assert inside `HasNameMatcher::matchesNode`.

clang/docs/ReleaseNotes.rst

@@ -647,6 +647,9 @@ AST Matchers
 
 - Fixed a crash when traverse lambda expr with invalid captures. (#GH106444)
 
+- Ensure ``hasName`` matches template specializations across inline namespaces,
+  making `matchesNodeFullSlow` and `matchesNodeFullFast` consistent.
+
 clang-format
 ------------
 

clang/include/clang/AST/PrettyPrinter.h

@@ -55,15 +55,17 @@ class PrintingCallbacks {
 /// This type is intended to be small and suitable for passing by value.
 /// It is very frequently copied.
 struct PrintingPolicy {
+  enum SuppressInlineNamespaceMode : uint8_t { None, Redundant, All };
+
   /// Create a default printing policy for the specified language.
   PrintingPolicy(const LangOptions &LO)
       : Indentation(2), SuppressSpecifiers(false),
         SuppressTagKeyword(LO.CPlusPlus), IncludeTagDefinition(false),
         SuppressScope(false), SuppressUnwrittenScope(false),
-        SuppressInlineNamespace(true), SuppressElaboration(false),
-        SuppressInitializers(false), ConstantArraySizeAsWritten(false),
-        AnonymousTagLocations(true), SuppressStrongLifetime(false),
-        SuppressLifetimeQualifiers(false),
+        SuppressInlineNamespace(SuppressInlineNamespaceMode::Redundant),
+        SuppressElaboration(false), SuppressInitializers(false),
+        ConstantArraySizeAsWritten(false), AnonymousTagLocations(true),
+        SuppressStrongLifetime(false), SuppressLifetimeQualifiers(false),
         SuppressTemplateArgsInCXXConstructors(false),
         SuppressDefaultTemplateArgs(true), Bool(LO.Bool),
         Nullptr(LO.CPlusPlus11 || LO.C23), NullptrTypeInNamespace(LO.CPlusPlus),
@@ -141,10 +143,12 @@ struct PrintingPolicy {
   unsigned SuppressUnwrittenScope : 1;
 
   /// Suppress printing parts of scope specifiers that correspond
-  /// to inline namespaces, where the name is unambiguous with the specifier
+  /// to inline namespaces.
+  /// If Redudant, where the name is unambiguous with the specifier removed.
+  /// If All, even if the name is ambiguous with the specifier
   /// removed.
-  LLVM_PREFERRED_TYPE(bool)
-  unsigned SuppressInlineNamespace : 1;
+  LLVM_PREFERRED_TYPE(SuppressInlineNamespaceMode)
+  unsigned SuppressInlineNamespace : 2;
 
   /// Ignore qualifiers and tag keywords as specified by elaborated type sugar,
   /// instead letting the underlying type print as normal.

clang/lib/AST/Decl.cpp

@@ -1737,9 +1737,17 @@ void NamedDecl::printNestedNameSpecifier(raw_ostream &OS,
       continue;
 
     // Suppress inline namespace if it doesn't make the result ambiguous.
-    if (P.SuppressInlineNamespace && Ctx->isInlineNamespace() && NameInScope &&
-        cast<NamespaceDecl>(Ctx)->isRedundantInlineQualifierFor(NameInScope))
-      continue;
+    if (Ctx->isInlineNamespace() && NameInScope) {
+      bool isRedundant =
+          cast<NamespaceDecl>(Ctx)->isRedundantInlineQualifierFor(NameInScope);
+      if (P.SuppressInlineNamespace ==
+              PrintingPolicy::SuppressInlineNamespaceMode::All ||
+          (P.SuppressInlineNamespace ==
+               PrintingPolicy::SuppressInlineNamespaceMode::Redundant &&
+           isRedundant)) {
+        continue;
+      }
+    }
 
     // Skip non-named contexts such as linkage specifications and ExportDecls.
     const NamedDecl *ND = dyn_cast<NamedDecl>(Ctx);

clang/lib/AST/TypePrinter.cpp

@@ -1413,7 +1413,9 @@ void TypePrinter::AppendScope(DeclContext *DC, raw_ostream &OS,
 
     // Only suppress an inline namespace if the name has the same lookup
     // results in the enclosing namespace.
-    if (Policy.SuppressInlineNamespace && NS->isInline() && NameInScope &&
+    if (Policy.SuppressInlineNamespace !=
+            PrintingPolicy::SuppressInlineNamespaceMode::None &&
+        NS->isInline() && NameInScope &&
         NS->isRedundantInlineQualifierFor(NameInScope))
       return AppendScope(DC->getParent(), OS, NameInScope);
 

clang/lib/ASTMatchers/ASTMatchersInternal.cpp

@@ -655,7 +655,9 @@ bool HasNameMatcher::matchesNodeFullSlow(const NamedDecl &Node) const {
 
     PrintingPolicy Policy = Node.getASTContext().getPrintingPolicy();
     Policy.SuppressUnwrittenScope = SkipUnwritten;
-    Policy.SuppressInlineNamespace = SkipUnwritten;
+    Policy.SuppressInlineNamespace =
+        SkipUnwritten ? PrintingPolicy::SuppressInlineNamespaceMode::All
+                      : PrintingPolicy::SuppressInlineNamespaceMode::None;
     Node.printQualifiedName(OS, Policy);
 
     const StringRef FullName = OS.str();

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -287,7 +287,8 @@ PrintingPolicy CGDebugInfo::getPrintingPolicy() const {
     PP.SplitTemplateClosers = true;
   }
 
-  PP.SuppressInlineNamespace = false;
+  PP.SuppressInlineNamespace =
+      PrintingPolicy::SuppressInlineNamespaceMode::None;
   PP.PrintCanonicalTypes = true;
   PP.UsePreferredNames = false;
   PP.AlwaysIncludeTypeForTemplateArgument = true;

clang/lib/CodeGen/CodeGenTypes.cpp

@@ -60,7 +60,8 @@ void CodeGenTypes::addRecordTypeName(const RecordDecl *RD,
   // example, we should probably enable PrintCanonicalTypes and
   // FullyQualifiedNames.
   PrintingPolicy Policy = RD->getASTContext().getPrintingPolicy();
-  Policy.SuppressInlineNamespace = false;
+  Policy.SuppressInlineNamespace =
+      PrintingPolicy::SuppressInlineNamespaceMode::None;
 
   // Name the codegen type after the typedef name
   // if there is no tag type name available

clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

@@ -2599,6 +2599,35 @@ TEST_P(ASTMatchersTest, HasName_MatchesInlinedNamespaces) {
   EXPECT_TRUE(matches(code, recordDecl(hasName("::a::C"))));
 }
 
+TEST_P(ASTMatchersTest, HasName_MatchesSpecializedInlinedNamespace) {
+  if (!GetParam().isCXX11OrLater()) {
+    return;
+  }
+
+  StringRef code = R"(
+namespace a {
+    inline namespace v1 {
+        template<typename T> T foo(T);
+    }
+}
+
+namespace a {
+    enum Tag{T1, T2};
+
+    template <Tag, typename T> T foo(T);
+}
+
+auto v1 = a::foo(1);
+auto v2 = a::foo<a::T1>(1);
+)";
+  EXPECT_TRUE(matches(
+      code, varDecl(hasName("v1"), hasDescendant(callExpr(callee(
+                                       functionDecl(hasName("::a::foo"))))))));
+  EXPECT_TRUE(matches(
+      code, varDecl(hasName("v2"), hasDescendant(callExpr(callee(
+                                       functionDecl(hasName("::a::foo"))))))));
+}
+
 TEST_P(ASTMatchersTest, HasName_MatchesAnonymousNamespaces) {
   if (!GetParam().isCXX()) {
     return;