================
@@ -395,6 +395,33 @@ bool Sema::checkStringLiteralArgumentAttr(const ParsedAttr
&AL, unsigned ArgNum,
return checkStringLiteralArgumentAttr(AL, ArgExpr, Str, ArgLocation);
}
+/// Check if the argument \p ArgNum of \p Attr is a compile-time constant
+/// integer (boolean) expression. If not, emit an error and return false.
+bool Sema::checkBoolExprArgumentAttr(const ParsedAttr &AL, unsigned ArgNum,
+ bool &Value) {
+ if (AL.isInvalid()) {
+ return false;
+ }
+ Expr *ArgExpr = AL.getArgAsExpr(ArgNum);
+ SourceLocation ErrorLoc(AL.getLoc());
+
+ if (AL.isArgIdent(ArgNum)) {
+ IdentifierLoc *IL = AL.getArgAsIdent(ArgNum);
+ ErrorLoc = IL->Loc;
+ } else if (ArgExpr != nullptr) {
+ if (const std::optional<llvm::APSInt> MaybeVal =
+ ArgExpr->getIntegerConstantExpr(Context, &ErrorLoc)) {
+ Value = MaybeVal->getBoolValue();
+ return true;
+ }
+ }
----------------
Sirraide wrote:
> how would we represent nolock(expression) before we can evaluate the
> expression?
You just store the dependent expression in the attribute. If it’s dependent,
then you only check whether it’s convertible (and whether it’s `true`) when you
instantiate this attribute by running Sema on it again. As I already mentioned,
you can take a look at how `CXXAssumeAttr` is handled (I implemented that one
recently; it has to deal w/ almost all of that as well, so you should be able
to get an idea as to what you need to do; you can ignore all the custom parsing
code for it, though), to get an idea as to what you need to do.
> And when would it be collapsed back into a concretely true or false form?
The expression in the attribute itself? Never, pretty much. I’ll just stay as
an expression, and you can evaluate it to figure out whether it’s `true` or
`false` (afaik you can wrap the expression in a `ConstantExpr` after evaluating
it to avoid having to re-evaluate it over and over again).
Feel free to ask if you have any more questions about this; I recall this
having been quite confusing for me as well when I had to figure out how all of
this actually works...
https://github.com/llvm/llvm-project/pull/84983
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