[clang] [WebKit checkers] Add support for ns_returns_autoreleased (PR #161236)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-static-analyzer-1

@llvm/pr-subscribers-clang

Author: Ryosuke Niwa (rniwa)

<details>
<summary>Changes</summary>

Recognize ns_returns_autoreleased on a function and treat its return value as a safe pointer origin.

---
Full diff: https://github.com/llvm/llvm-project/pull/161236.diff


3 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp (+2-1) 
- (modified) clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm (+11) 
- (modified) clang/test/Analysis/Checkers/WebKit/unretained-local-vars.mm (+12) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
index 00a1b8b6e7e89..37c22e0597dff 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/ASTUtils.cpp
@@ -93,7 +93,8 @@ bool tryToFindPtrOrigin(
     if (auto *call = dyn_cast<CallExpr>(E)) {
       if (auto *Callee = call->getCalleeDecl()) {
         if (Callee->hasAttr<CFReturnsRetainedAttr>() ||
-            Callee->hasAttr<NSReturnsRetainedAttr>()) {
+            Callee->hasAttr<NSReturnsRetainedAttr>() ||
+            Callee->hasAttr<NSReturnsAutoreleasedAttr>()) {
           return callback(E, true);
         }
       }
diff --git a/clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm b/clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm
index c9d2fe861bb49..3c42ac61bdecf 100644
--- a/clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm
+++ b/clang/test/Analysis/Checkers/WebKit/unretained-call-args.mm
@@ -561,6 +561,17 @@ void foo() {
 
 } // namespace ns_retained_return_value
 
+namespace autoreleased {
+
+NSString *provideAutoreleased() __attribute__((ns_returns_autoreleased));
+void consume(NSString *);
+
+void foo() {
+  consume(provideAutoreleased());
+}
+
+} // autoreleased
+
 @interface TestObject : NSObject
 - (void)doWork:(NSString *)msg, ...;
 - (void)doWorkOnSelf;
diff --git a/clang/test/Analysis/Checkers/WebKit/unretained-local-vars.mm b/clang/test/Analysis/Checkers/WebKit/unretained-local-vars.mm
index 307a4d03fe101..72ba05e9e3a71 100644
--- a/clang/test/Analysis/Checkers/WebKit/unretained-local-vars.mm
+++ b/clang/test/Analysis/Checkers/WebKit/unretained-local-vars.mm
@@ -535,6 +535,18 @@ unsigned foo() {
 
 } // namespace ns_retained_return_value
 
+namespace autoreleased {
+
+NSString *provideAutoreleased() __attribute__((ns_returns_autoreleased));
+void consume(NSString *);
+
+void foo() {
+  auto *string = provideAutoreleased();
+  consume(string);
+}
+
+} // autoreleased
+
 bool doMoreWorkOpaque(OtherObj*);
 SomeObj* provide();
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/161236