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

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@@ -783,6 +783,9 @@ def err_ms_property_expected_comma_or_rparen : Error<
 def err_ms_property_initializer : Error<
   "property declaration cannot have a default member initializer">;
 
+def err_assume_attr_expects_cond_expr : Error<
+  "use of this expression in an 'assume' attribute requires parentheses">;
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Sirraide wrote:

Speaking of `clang::assume`: We could add a warning in Sema that suggests using that instead if someone writes e.g. `[[assume("foo")]]` seeing as that tautological, albeit valid.

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