[clang] [Clang][C++23] Implement P1774R8: Portable assumptions (PR #81014)

[Erich Keane via cfe-commits]

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@@ -4528,6 +4528,54 @@ static bool IsBuiltInOrStandardCXX11Attribute(IdentifierInfo *AttrName,
   }
 }
 
+/// Parse the argument to C++23's [[assume()]] attribute.
+bool Parser::ParseAssumeAttributeArg(ParsedAttributes &Attrs,
+                                     IdentifierInfo *AttrName,
+                                     SourceLocation AttrNameLoc,
+                                     SourceLocation *EndLoc) {
+  assert(Tok.is(tok::l_paren) && "Not a C++11 attribute argument list");
+  BalancedDelimiterTracker T(*this, tok::l_paren);
+  T.consumeOpen();
+
+  // [dcl.attr.assume]: The expression is potentially evaluated.
+  EnterExpressionEvaluationContext Unevaluated(
+      Actions, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
+
+  TentativeParsingAction TPA(*this);
+  ExprResult Res(
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erichkeane wrote:

Does this check contextually convertible to bool?

https://github.com/llvm/llvm-project/pull/81014