[PATCH] D116775: [clang][#47272] Avoid suggesting deprecated version of a declaration over another in typo correction

[Markus Böck via Phabricator via cfe-commits]

zero9178 marked 2 inline comments as done.
zero9178 added inline comments.


================
Comment at: clang/lib/Sema/SemaLookup.cpp:4345
+      return;
     }
   }
----------------
Quuxplusone wrote:
> It seems like this code is overdue for a "compare these two corrections" //predicate//. The simple version would be
> ```
> auto IsBetter = [&](const TypoCorrection& TC1, const TypoCorrection& TC2) {
>     std::pair<bool, std::string> Key1 = { IsDeprecated(TC1.getFoundDecl()), TC1.getAsString(SemaRef.getLangOpts()) };
>     std::pair<bool, std::string> Key2 = { IsDeprecated(TC2.getFoundDecl()), TC2.getAsString(SemaRef.getLangOpts()) };
>     return Key1 < Key2;  // prefer non-deprecated, alphabetically earlier declarations
> };
> for (TypoCorrection& TC : CList) {
>     if (IsBetter(Correction, TC))
>         TC = Correction;
> }
> ```
> Actually, you could even replicate the hoisting of the loop-invariant stuff, the way the old code did:
> ```
> std::pair<bool, std::string> CorrectionKey = { IsDeprecated(Correction.getFoundDecl()), Correction.getAsString(SemaRef.getLangOpts()) };
> auto CorrectionIsBetterThan = [&](const TypoCorrection& TC) {
>     std::pair<bool, std::string> Key = { IsDeprecated(TC.getFoundDecl()), TC.getAsString(SemaRef.getLangOpts()) };
>     return CorrectionKey < Key;  // prefer non-deprecated, alphabetically earlier declarations
> };
> for (TypoCorrection& TC : CList) {
>     if (CorrectionIsBetterThan(TC))
>         TC = Correction;
> }
> ```
Thanks I really liked the idea of using std::pairs comparison for that. 
I chose to separate the concerns, by first finding the declaration in the list and only then using the comparison of the found decl and the new correction. 


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