[webkit.UncountedLambdaCapturesChecker] Support [[clang::noescape]] on a constructor (#126869)

Added the support for annotating a constructor's argument with
[[clang::noescape]].

We explicitly ignore CXXConstructExpr which is visited as a part of
CallExpr so that construction of closures like Function,
CompletionHandler, etc... don't result in a warning.

Author: rniwa

clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp

@@ -41,6 +41,7 @@ class UncountedLambdaCapturesChecker
       const UncountedLambdaCapturesChecker *Checker;
       llvm::DenseSet<const DeclRefExpr *> DeclRefExprsToIgnore;
       llvm::DenseSet<const LambdaExpr *> LambdasToIgnore;
+      llvm::DenseSet<const CXXConstructExpr *> ConstructToIgnore;
       QualType ClsType;
 
       explicit LocalVisitor(const UncountedLambdaCapturesChecker *Checker)
@@ -106,6 +107,26 @@ class UncountedLambdaCapturesChecker
         return safeGetName(NsDecl) == "WTF" && safeGetName(Decl) == "switchOn";
       }
 
+      bool VisitCXXConstructExpr(CXXConstructExpr *CE) override {
+        if (ConstructToIgnore.contains(CE))
+          return true;
+        if (auto *Callee = CE->getConstructor()) {
+          unsigned ArgIndex = 0;
+          for (auto *Param : Callee->parameters()) {
+            if (ArgIndex >= CE->getNumArgs())
+              return true;
+            auto *Arg = CE->getArg(ArgIndex)->IgnoreParenCasts();
+            if (auto *L = findLambdaInArg(Arg)) {
+              LambdasToIgnore.insert(L);
+              if (!Param->hasAttr<NoEscapeAttr>())
+                Checker->visitLambdaExpr(L, shouldCheckThis());
+            }
+            ++ArgIndex;
+          }
+        }
+        return true;
+      }
+
       bool VisitCallExpr(CallExpr *CE) override {
         checkCalleeLambda(CE);
         if (auto *Callee = CE->getDirectCallee()) {
@@ -143,8 +164,10 @@ class UncountedLambdaCapturesChecker
         auto *CtorArg = CE->getArg(0)->IgnoreParenCasts();
         if (!CtorArg)
           return nullptr;
-        if (auto *Lambda = dyn_cast<LambdaExpr>(CtorArg))
+        if (auto *Lambda = dyn_cast<LambdaExpr>(CtorArg)) {
+          ConstructToIgnore.insert(CE);
           return Lambda;
+        }
         auto *DRE = dyn_cast<DeclRefExpr>(CtorArg);
         if (!DRE)
           return nullptr;
@@ -157,6 +180,7 @@ class UncountedLambdaCapturesChecker
         TempExpr = dyn_cast<CXXBindTemporaryExpr>(Init->IgnoreParenCasts());
         if (!TempExpr)
           return nullptr;
+        ConstructToIgnore.insert(CE);
         return dyn_cast_or_null<LambdaExpr>(TempExpr->getSubExpr());
       }
 

clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures.cpp

@@ -298,7 +298,11 @@ struct RefCountableWithLambdaCapturingThis {
     callLambda([&]() -> RefPtr<RefCountable> {
       return obj->next();
     });
+    WTF::HashMap<int, RefPtr<RefCountable>> anotherMap([&] {
+      return obj->next();
+    });
   }
+
 };
 
 struct NonRefCountableWithLambdaCapturingThis {