[clang] nolock/noalloc attributes (PR #84983)

[Doug Wyatt via cfe-commits]

================
@@ -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;
+    }
+  }
----------------
dougsonos wrote:

Thank you! I was looking for precedents for this and couldn't find it on any attributes. It bugged me that I was writing something like this.

Yes, the parameter can be an arbitrary expression.

But if it is dependent: then how would we represent `nolock(expression)` before we can evaluate the expression? And when would it be collapsed back into a concretely true or false form?

https://github.com/llvm/llvm-project/pull/84983