This PR makes webkit.UncountedLambdaCapturesChecker ignore trivial
functions as well as the one being passed to an argument with
[[clang::noescape]] attribute. This dramatically reduces the false
positive rate for this checker.
To do this, this PR replaces VisitLambdaExpr in favor of checking
lambdas via VisitDeclRefExpr and VisitCallExpr. The idea is that if a
lambda is defined but never called or stored somewhere, then capturing
whatever variable in such a lambda is harmless.
VisitCallExpr explicitly looks for direct invocation of lambdas and
registers its DeclRefExpr to be ignored in VisitDeclRefExpr. If a lambda
is being passed to a function, it checks whether its argument is
annotated with [[clang::noescape]]. If it's not annotated such, it
checks captures for their safety.
Because WTF::switchOn could not be annotated with [[clang::noescape]] as
function type parameters are variadic template function so we hard-code
this function into the checker.
Finally, this PR also converts the accompanying test to use -verify and
adds a bunch of tests.
The attribute is now allowed on an assortment of declarations, to
suppress warnings related to declarations themselves, or all warnings in
the lexical scope of the declaration.
I don't necessarily see a reason to have a list at all, but it does look
as if some of those more niche items aren't properly supported by the
compiler itself so let's maintain a short safe list for now.
The initial implementation raised a question whether the attribute
should apply to lexical declaration context vs. "actual" declaration
context. I'm using "lexical" here because it results in less warnings
suppressed, which is the conservative behavior: we can always expand it
later if we think this is wrong, without breaking any existing code. I
also think that this is the correct behavior that we will probably never
want to change, given that the user typically desires to keep the
suppressions as localized as possible.
Show line numbers to the left of diagnostic code snippets and increase
the numbers of lines shown from 1 to 16.
Differential Revision: https://reviews.llvm.org/D147875
Show line numbers to the left of diagnostic code snippets and increase
the numbers of lines shown from 1 to 16.
Differential Revision: https://reviews.llvm.org/D147875
