[Clang][ASTMatcher] Add dependentScopeDeclRefExpr matcher (#120996)

Fixes #120937

clang/docs/LibASTMatchersReference.html

@@ -1842,6 +1842,12 @@ <h2 id="decl-matchers">Node Matchers</h2>
   if (x) {}
 </pre></td></tr>
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('dependentScopeDeclRefExpr0')"><a name="dependentScopeDeclRefExpr0Anchor">dependentScopeDeclRefExpr</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1DependentScopeDeclRefExpr.html">DependentScopeDeclRefExpr</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="dependentScopeDeclRefExpr0"><pre>Matches expressions that refer to dependent scope declarations.
+
+Example matches T::v
+   template <class T> class X : T { void f() { T::v; } };
+</pre></td></tr>
 
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('declStmt0')"><a name="declStmt0Anchor">declStmt</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1DeclStmt.html">DeclStmt</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="declStmt0"><pre>Matches declaration statements.

clang/docs/ReleaseNotes.rst

@@ -1108,6 +1108,8 @@ AST Matchers
 
 - Ensure ``pointee`` matches Objective-C pointer types.
 
+- Add ``dependentScopeDeclRefExpr`` matcher to match expressions that refer to dependent scope declarations.
+
 clang-format
 ------------
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -2125,6 +2125,16 @@ extern const internal::VariadicDynCastAllOfMatcher<Stmt, Expr> expr;
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, DeclRefExpr>
     declRefExpr;
 
+/// Matches expressions that refer to dependent scope declarations.
+///
+/// example matches T::v;
+/// \code
+///  template <class T> class X : T { void f() { T::v; } };
+/// \endcode
+extern const internal::VariadicDynCastAllOfMatcher<Stmt,
+                                                   DependentScopeDeclRefExpr>
+    dependentScopeDeclRefExpr;
+
 /// Matches a reference to an ObjCIvar.
 ///
 /// Example: matches "a" in "init" method:

clang/lib/ASTMatchers/ASTMatchersInternal.cpp

@@ -924,6 +924,8 @@ const internal::VariadicDynCastAllOfMatcher<Stmt, CXXRewrittenBinaryOperator>
 const internal::VariadicDynCastAllOfMatcher<Stmt, CXXFoldExpr> cxxFoldExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, Expr> expr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, DeclRefExpr> declRefExpr;
+const internal::VariadicDynCastAllOfMatcher<Stmt, DependentScopeDeclRefExpr>
+    dependentScopeDeclRefExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, ObjCIvarRefExpr> objcIvarRefExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, BlockExpr> blockExpr;
 const internal::VariadicDynCastAllOfMatcher<Stmt, IfStmt> ifStmt;

clang/lib/ASTMatchers/Dynamic/Registry.cpp

@@ -222,6 +222,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(decompositionDecl);
   REGISTER_MATCHER(declCountIs);
   REGISTER_MATCHER(declRefExpr);
+  REGISTER_MATCHER(dependentScopeDeclRefExpr);
   REGISTER_MATCHER(declStmt);
   REGISTER_MATCHER(declaratorDecl);
   REGISTER_MATCHER(decltypeType);

clang/unittests/AST/ASTImporterTest.cpp

@@ -3172,9 +3172,6 @@ TEST_P(ImportDecl, ImportFieldOrder) {
              recordDecl(hasFieldOrder({"b", "a"})));
 }
 
-const internal::VariadicDynCastAllOfMatcher<Expr, DependentScopeDeclRefExpr>
-    dependentScopeDeclRefExpr;
-
 TEST_P(ImportExpr, DependentScopeDeclRefExpr) {
   MatchVerifier<Decl> Verifier;
   testImport("template <typename T> struct S { static T foo; };"

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

@@ -556,6 +556,21 @@ TEST_P(ASTMatchersTest, DeclRefExpr) {
                          Reference));
 }
 
+TEST_P(ASTMatchersTest, DependentScopeDeclRefExpr) {
+  if (!GetParam().isCXX() || GetParam().hasDelayedTemplateParsing()) {
+    // FIXME: Fix this test to work with delayed template parsing.
+    return;
+  }
+
+  EXPECT_TRUE(matches("template <class T> class X : T { void f() { T::v; } };",
+                      dependentScopeDeclRefExpr()));
+
+  EXPECT_TRUE(
+      matches("template <typename T> struct S { static T Foo; };"
+              "template <typename T> void declToImport() { (void)S<T>::Foo; }",
+              dependentScopeDeclRefExpr()));
+}
+
 TEST_P(ASTMatchersTest, CXXMemberCallExpr) {
   if (!GetParam().isCXX()) {
     return;
@@ -629,10 +644,8 @@ TEST_P(ASTMatchersTest, MemberExpr_MatchesVariable) {
   EXPECT_TRUE(matches("template <class T>"
                       "class X : T { void f() { this->T::v; } };",
                       cxxDependentScopeMemberExpr()));
-  // FIXME: Add a matcher for DependentScopeDeclRefExpr.
-  EXPECT_TRUE(
-      notMatches("template <class T> class X : T { void f() { T::v; } };",
-                 cxxDependentScopeMemberExpr()));
+  EXPECT_TRUE(matches("template <class T> class X : T { void f() { T::v; } };",
+                      dependentScopeDeclRefExpr()));
   EXPECT_TRUE(matches("template <class T> void x() { T t; t.v; }",
                       cxxDependentScopeMemberExpr()));
 }