[clang] [C23] Implement N3018: The constexpr specifier for object definitions (PR #73099)

[Aaron Ballman via cfe-commits]

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@@ -14277,6 +14325,113 @@ StmtResult Sema::ActOnCXXForRangeIdentifier(Scope *S, SourceLocation IdentLoc,
                                                       : IdentLoc);
 }
 
+static ImplicitConversionKind GetConversionKind(QualType FromType,
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AaronBallman wrote:

That's along the lines of what I was thinking, yes. I was hoping we could use something like `Sema::TryImplicitConversion()` to get us an implicit conversion sequence. From there, we could check to see if it's a standard conversion sequence to get the object which gives access to `StandardConversionSequence::getNarrowingKind()` to see if it's been narrowed.

https://github.com/llvm/llvm-project/pull/73099