[PATCH] D148924: [clang] Show error if defaulted comparions operator function is volatile or has ref-qualifier &&.

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov added a reviewer: clang-language-wg.
ilya-biryukov added a comment.

Thanks! I believe we should also recover in the similar manner we do for missing `const`, see corresponding comment.

Extra NITs:

- there is a typo in description: *compariosn* should be comparison,
- we probably want to add this change to release notes.

Also adding @clang-language-wg in case someone else wants to chime in.



================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:9434
+def err_volatile_comparison_operator : Error<
+  "defaulted comparison operator function must not be volatile">;
+def err_ref_qualifier_comparison_operator : Error<
----------------
NIT: for consistency with wording of notes above.


================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:9436
+def err_ref_qualifier_comparison_operator : Error<
+  "ref-qualifier '&&' is not allowed on defaulted comparison operators">;
 
----------------
NIT: for consistency with the wording of `err_ref_qualifier_constructor`


================
Comment at: clang/lib/Sema/SemaDeclCXX.cpp:8593-8601
+    const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
+    if (FnType->isVolatile()) {
+      Diag(FD->getLocation(), diag::err_volatile_comparison_operator);
+      return true;
+    }
+    if (FnType->getRefQualifier() == RQ_RValue) {
+      Diag(FD->getLocation(), diag::err_ref_qualifier_comparison_operator);
----------------
NIT: this version is simpler and more aligned with the code below.
Also, could you move the `volatile` handling after the check for `const`?


Additionally, we seem to recover in case of `const` by adding it to the type and suggesting a fix-it to add it in the code.
Could we do the same for `volatile` and `ref-qualifier`, i.e. suggest a fix-it to remove the `ref-qualifier` and `volatile` and change the corresponding type to make AST pretend they were never there?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D148924/new/

https://reviews.llvm.org/D148924