================
@@ -16538,6 +16538,24 @@ void Sema::DiagnoseAlwaysNonNullPointer(Expr *E,
}
}
+ // Complain if we are converting a lambda expression to a boolean value
+ if (const auto *MCallExpr = dyn_cast<CXXMemberCallExpr>(E)) {
+ if (MCallExpr->getObjectType()->isRecordType()) {
+ if (const auto *MRecordDecl = MCallExpr->getRecordDecl()) {
+ if (MRecordDecl->isLambda()) {
+ std::string Str;
+ llvm::raw_string_ostream S(Str);
+
+ E->printPretty(S, nullptr, getPrintingPolicy());
+ Diag(E->getExprLoc(), diag::warn_impcast_pointer_to_bool)
+ << /*FunctionPointerType*/ 1 << S.str() << E->getSourceRange()
+ << Range << IsEqual;
+ return;
+ }
+ }
+ }
+ }
----------------
AaronBallman wrote:
Actually, I'm not convinced we *should* print the entire expression in this
case. Lambdas usually aren't nearly as trivial as the ones we have in our test
cases, and can be arbitrarily long. e.g.,
```
C:\Users\aballman\OneDrive - Intel Corporation\Desktop\test.cpp:2:7: warning:
address of function '[]() {
int foo = 0;
return foo;
}' will always evaluate to 'true' [-Wpointer-bool-conversion]
2 | if ([](){
| ~~ ^~~~~
3 | // This is a comment
| ~~~~~~~~~~~~~~~~~~~~
4 | // intended to make the lambda
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 | // longer so that it shows
| ~~~~~~~~~~~~~~~~~~~~~~~~~~
6 | // what the diagnostic behavior is
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
7 | int foo = 0;
| ~~~~~~~~~~~~
8 | // of really large lambdas, and whether
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9 | // it is worth it to print out the entire
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
10 | // expression in this case.
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~
11 | return foo;
| ~~~~~~~~~~~
12 | }) {
| ~
1 warning generated.
```
This has two problems: 1) it repeats the user's code in both the diagnostic and
in the highlighting, 2) the amount of context is huge and distracts from the
diagnostic.
I think we should modify `warn_impcast_pointer_to_bool` to something along
these lines:
```
def warn_impcast_pointer_to_bool : Warning<
"address of%select{| function| array| lambda function pointer conversion
operator}0 '%1' will always evaluate to 'true'">,
InGroup<PointerBoolConversion>;
```
(Will need to be reformatted for the usual 80-col limits.) And when passing the
source range for the lambda expression, I think we should pass only the lambda
introducer as the source range so that we highlight far less code.
WDYT?
https://github.com/llvm/llvm-project/pull/83152
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