[clang] [Clang][ASTMatcher] Improve matching isDerivedFrom base in case of multi aliases exists (PR #126793)

[Amr Hesham via cfe-commits]

https://github.com/AmrDeveloper updated https://github.com/llvm/llvm-project/pull/126793

>From cfa6bfb6ae5834f251d8e0c2c0f447aa82c97ef2 Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Tue, 11 Feb 2025 21:30:18 +0100
Subject: [PATCH 1/2] [Clang][ASTMatcher] Improve matching isDerivedFrom base
 in case of multi alias exists

---
 clang/lib/ASTMatchers/ASTMatchFinder.cpp      | 21 +++++++++++++++++++
 .../ASTMatchers/ASTMatchersNarrowingTest.cpp  | 17 +++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/clang/lib/ASTMatchers/ASTMatchFinder.cpp b/clang/lib/ASTMatchers/ASTMatchFinder.cpp
index 3d01a70395a9b..e9ec7eff1e0ab 100644
--- a/clang/lib/ASTMatchers/ASTMatchFinder.cpp
+++ b/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)) {
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
index 5e1c12ba26d87..4e6baedae2be5 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ b/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(

>From 08d0a789519a751012ba9ee22e5e3e68954ea1ec Mon Sep 17 00:00:00 2001
From: AmrDeveloper <amr96 at programmer.net>
Date: Wed, 5 Mar 2025 18:22:12 +0100
Subject: [PATCH 2/2] Add a releasenote

---
 clang/docs/ReleaseNotes.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 35efa2ca4aa93..9f0af6cbbdac4 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -361,6 +361,8 @@ Fixed Point Support in Clang
 AST Matchers
 ------------
 
+- Ensure ``isDerivedFrom`` is matching the correct base in case of more than one aliases exists.
+
 clang-format
 ------------