[clang] [clang][ssaf] CallGraph extrator should account for objc callees (PR #202606)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-ssaf

Author: Balázs Benics (steakhal)

<details>
<summary>Changes</summary>

Fixes: rdar://179104950

---
Full diff: https://github.com/llvm/llvm-project/pull/202606.diff


2 Files Affected:

- (modified) clang/lib/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractor.cpp (+7-3) 
- (modified) clang/unittests/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractorTest.cpp (+42) 


``````````diff
diff --git a/clang/lib/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractor.cpp b/clang/lib/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractor.cpp
index 6e0b0ee8fe834..6dfb66a283674 100644
--- a/clang/lib/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractor.cpp
+++ b/clang/lib/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractor.cpp
@@ -72,9 +72,13 @@ void CallGraphExtractor::handleCallGraphNode(const ASTContext &Ctx,
     // never null.
     assert(CalleeDecl);
 
-    // FIXME: `clang::CallGraph` does not consider ObjCMessageExprs as calls.
-    // Consequently, they don't appear as a Callee.
-    assert(!isa<ObjCMethodDecl>(CalleeDecl));
+    // `clang::CallGraph` resolves ObjCMessageExprs (including property
+    // dot-syntax) to their ObjCMethodDecls and adds them as callees — see
+    // `CGBuilder::VisitObjCMessageExpr` in clang/lib/Analysis/CallGraph.cpp.
+    // ObjC dispatch is dynamic, so recording these as direct callees would be
+    // misleading; skip them until we model ObjC properly.
+    if (isa<ObjCMethodDecl>(CalleeDecl))
+      continue;
 
     // FIXME: `clang::CallGraph` does not create entries for primary templates.
     assert(!CalleeDecl->isTemplated());
diff --git a/clang/unittests/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractorTest.cpp b/clang/unittests/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractorTest.cpp
index 39b3cf604857d..183fd7155cfba 100644
--- a/clang/unittests/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractorTest.cpp
+++ b/clang/unittests/ScalableStaticAnalysisFramework/Analyses/CallGraph/CallGraphExtractorTest.cpp
@@ -424,6 +424,48 @@ TEST_F(CallGraphExtractorTest, ObjCMessageExprs) {
       hasSummaryThat(HasNoDirectCallees(), HasNoVirtualCallees()));
 }
 
+TEST_F(CallGraphExtractorTest, ObjCMessageToLocallyImplementedMethod) {
+  // When the receiver class is implemented in the same TU, `clang::CallGraph`
+  // resolves the ObjCMessageExpr (via `lookupPrivateMethod`) to an
+  // ObjCMethodDecl and adds it as a callee. The extractor must not abort on
+  // these — ObjC dispatch is dynamic and we don't model it as a direct callee.
+  runExtractor(R"cpp(
+    @interface NSObject @end
+    @interface Inner : NSObject
+    - (int) val;
+    @end
+    @implementation Inner
+    - (int) val { return 42; }
+    @end
+    int caller(Inner *x) { return [x val]; }
+  )cpp",
+               {"-x", "objective-c"});
+
+  ASSERT_THAT_EXPECTED(
+      findSummary("caller"),
+      hasSummaryThat(HasNoDirectCallees(), HasNoVirtualCallees()));
+}
+
+TEST_F(CallGraphExtractorTest, ObjCPropertyDotSyntax) {
+  // Property dot-syntax (`x.val`) desugars to an ObjCMessageExpr to the
+  // synthesized getter; same dynamic dispatch as bracket syntax. Cover it
+  // explicitly because real-world hits often come through dot-syntax.
+  runExtractor(R"cpp(
+    @interface NSObject @end
+    @interface Inner : NSObject
+    @property (readonly) int val;
+    @end
+    @implementation Inner
+    @end
+    int caller(Inner *x) { return x.val; }
+  )cpp",
+               {"-x", "objective-c"});
+
+  ASSERT_THAT_EXPECTED(
+      findSummary("caller"),
+      hasSummaryThat(HasNoDirectCallees(), HasNoVirtualCallees()));
+}
+
 TEST_F(CallGraphExtractorTest, DefinitionLocation) {
   runExtractor(R"cpp(
     void callee_with_def() {}

``````````

</details>


https://github.com/llvm/llvm-project/pull/202606