[Clang][ASTMatcher] Improve matching isDerivedFrom base in case of multi alias exists

Author: AmrDeveloper

clang/lib/ASTMatchers/ASTMatchFinder.cpp

@@ -1287,6 +1287,27 @@ class MatchASTVisitor : public RecursiveASTVisitor<MatchASTVisitor>,
     auto Aliases = TypeAliases.find(CanonicalType);
     if (Aliases == TypeAliases.end())
       return false;
+
+    if (const auto *ElaboratedTypeNode =
+            llvm::dyn_cast<ElaboratedType>(TypeNode)) {
+      if (ElaboratedTypeNode->isSugared() && Aliases->second.size() > 1) {
+        const auto &DesugaredTypeName =
+            ElaboratedTypeNode->desugar().getAsString();
+
+        for (const TypedefNameDecl *Alias : Aliases->second) {
+          if (Alias->getName() != DesugaredTypeName) {
+            continue;
+          }
+
+          BoundNodesTreeBuilder Result(*Builder);
+          if (Matcher.matches(*Alias, this, &Result)) {
+            *Builder = std::move(Result);
+            return true;
+          }
+        }
+      }
+    }
+
     for (const TypedefNameDecl *Alias : Aliases->second) {
       BoundNodesTreeBuilder Result(*Builder);
       if (Matcher.matches(*Alias, this, &Result)) {

clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

@@ -1167,6 +1167,23 @@ TEST_P(ASTMatchersTest, IsDerivedFrom_EmptyName) {
   EXPECT_TRUE(notMatches(Code, cxxRecordDecl(isSameOrDerivedFrom(""))));
 }
 
+TEST_P(ASTMatchersTest, IsDerivedFrom_ElaboratedType) {
+  if (!GetParam().isCXX()) {
+    return;
+  }
+
+  DeclarationMatcher IsDerivenFromBase =
+      cxxRecordDecl(isDerivedFrom(decl().bind("typedef")));
+
+  EXPECT_TRUE(matchAndVerifyResultTrue(
+      "struct AnInterface {};"
+      "typedef AnInterface UnusedTypedef;"
+      "typedef AnInterface Base;"
+      "class AClass : public Base {};",
+      IsDerivenFromBase,
+      std::make_unique<VerifyIdIsBoundTo<TypedefDecl>>("typedef", "Base")));
+}
+
 TEST_P(ASTMatchersTest, IsDerivedFrom_ObjC) {
   DeclarationMatcher IsDerivedFromX = objcInterfaceDecl(isDerivedFrom("X"));
   EXPECT_TRUE(