[clang analysis] Make mutex guard detection more reliable.

-Wthread-safety was failing to detect certain AST patterns it should
detect. Make the pattern detection a bit more comprehensive.

Due to an unrelated bug involving template instantiation, this showed up
as a regression in 10.0 vs. 9.0 in the original bug report. The included
testcase fails on older versions of clang, though.

Fixes https://bugs.llvm.org/show_bug.cgi?id=45323 .

Differential Revision: https://reviews.llvm.org/D76943

Author: efriedma-quic

clang/lib/Analysis/ThreadSafety.cpp

@@ -2139,12 +2139,14 @@ void BuildLockset::VisitDeclStmt(const DeclStmt *S) {
 
       // handle constructors that involve temporaries
       if (auto *EWC = dyn_cast<ExprWithCleanups>(E))
-        E = EWC->getSubExpr();
-      if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
-        if (ICE->getCastKind() == CK_NoOp)
-          E = ICE->getSubExpr();
+        E = EWC->getSubExpr()->IgnoreParens();
+      if (auto *CE = dyn_cast<CastExpr>(E))
+        if (CE->getCastKind() == CK_NoOp ||
+            CE->getCastKind() == CK_ConstructorConversion ||
+            CE->getCastKind() == CK_UserDefinedConversion)
+          E = CE->getSubExpr()->IgnoreParens();
       if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(E))
-        E = BTE->getSubExpr();
+        E = BTE->getSubExpr()->IgnoreParens();
 
       if (const auto *CE = dyn_cast<CXXConstructExpr>(E)) {
         const auto *CtorD = dyn_cast_or_null<NamedDecl>(CE->getConstructor());

clang/test/SemaCXX/warn-thread-safety-analysis.cpp

@@ -5648,6 +5648,22 @@ namespace ReturnScopedLockable {
     auto ptr = get();
     return ptr->f();
   }
+  void use_constructor() {
+    auto ptr = ReadLockedPtr<Object>(nullptr);
+    ptr->f();
+    auto ptr2 = ReadLockedPtr<Object>{nullptr};
+    ptr2->f();
+    auto ptr3 = (ReadLockedPtr<Object>{nullptr});
+    ptr3->f();
+  }
+  struct Convertible {
+    Convertible();
+    operator ReadLockedPtr<Object>();
+  };
+  void use_conversion() {
+    ReadLockedPtr<Object> ptr = Convertible();
+    ptr->f();
+  }
 }
 
 namespace PR38640 {