[clang] [webkit.UncountedLambdaCapturesChecker] Ignore trivial functions and [[clang::noescape]]. (PR #114897)

[Ryosuke Niwa via cfe-commits]

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@@ -45,32 +52,118 @@ class UncountedLambdaCapturesChecker
       bool shouldVisitTemplateInstantiations() const { return true; }
       bool shouldVisitImplicitCode() const { return false; }
 
-      bool VisitLambdaExpr(LambdaExpr *L) {
-        Checker->visitLambdaExpr(L);
+      bool TraverseCXXMethodDecl(CXXMethodDecl *CXXMD) {
+        llvm::SaveAndRestore SavedDecl(ClsType);
+        ClsType = CXXMD->getThisType();
+        return Base::TraverseDecl(CXXMD);
+      }
+
+      bool shouldCheckThis() {
+        auto result = !ClsType.isNull() ? isUnsafePtr(ClsType) : std::nullopt;
+        return result && *result;
+      }
+
+      bool VisitDeclRefExpr(DeclRefExpr *DRE) {
+        if (DeclRefExprsToIgnore.contains(DRE))
+          return true;
+        auto *VD = dyn_cast_or_null<VarDecl>(DRE->getDecl());
+        if (!VD)
+          return true;
+        auto *Init = VD->getInit();
+        if (!Init)
+          return true;
+        auto *L = dyn_cast_or_null<LambdaExpr>(Init->IgnoreParenCasts());
+        if (!L)
+          return true;
+        Checker->visitLambdaExpr(L, shouldCheckThis());
         return true;
       }
+
+      // WTF::switchOn(T, F... f) is a variadic template function and couldn't
+      // be annotated with NOESCAPE. We hard code it here to workaround that.
+      bool shouldTreatAllArgAsNoEscape(FunctionDecl *Decl) {
+        auto *NsDecl = Decl->getParent();
+        if (!NsDecl || !isa<NamespaceDecl>(NsDecl))
+          return false;
+        return safeGetName(NsDecl) == "WTF" && safeGetName(Decl) == "switchOn";
+      }
+
+      bool VisitCallExpr(CallExpr *CE) {
+        checkCalleeLambda(CE);
+        if (auto *Callee = CE->getDirectCallee()) {
+          bool TreatAllArgsAsNoEscape = shouldTreatAllArgAsNoEscape(Callee);
+          unsigned ArgIndex = 0;
+          for (auto *Param : Callee->parameters()) {
+            if (ArgIndex >= CE->getNumArgs())
+              break;
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rniwa wrote:

Sure, we can do that.

https://github.com/llvm/llvm-project/pull/114897