[PATCH] D102251: Suppress Deferred Diagnostics in discarded statements.

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

(No blocking concerns here.)



================
Comment at: clang/lib/AST/Stmt.cpp:1000-1003
+  if (Optional<Stmt *> Result =
+          const_cast<IfStmt *>(this)->getNondiscardedCase(Ctx))
+    return *Result;
+  return None;
----------------
Can this simply be
```
  return const_cast<IfStmt *>(this)->getNondiscardedCase(Ctx));
```
? I would expect that if `T` implicitly converts to `U` then `Optional<T>` implicitly converts to `Optional<U>`.


================
Comment at: clang/lib/Sema/Sema.cpp:1545
 class DeferredDiagnosticsEmitter
     : public UsedDeclVisitor<DeferredDiagnosticsEmitter> {
 public:
----------------
I wonder if there are other `UsedDeclVisitor`s that would want this behavior, largely because of [basic.def.odr]p10: "Every program shall contain exactly one definition of every non-inline function or variable that is odr-used in that program outside of a discarded statement (8.5.2)". It seems worth checking, and maybe moving this functionality to an optional behavior in the base class, but I don't want to hold up this patch on that.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D102251/new/

https://reviews.llvm.org/D102251