Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Feb 14, 2025
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Original file line number Diff line number Diff line change
@@ -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)) {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

For my understanding: Is the LambdaExpr not covered in VisitLambdaExpr? What's special about the expression being an argument to a constructor?

Copy link
Contributor Author

@rniwa rniwa Feb 14, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh, so we wanna ignore lambda expressions that are passed to [[clang::noescape]] argument. The code in VisitCallExpr and now VisitCXXConstructExpr is there to detect this specific case, and then ignore the argument.

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());
}

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

};

struct NonRefCountableWithLambdaCapturingThis {