[PATCH] D69238: Fix clang-tidy readability-redundant-string-init for c++17/c++2a

[Conrad Poelman via Phabricator via cfe-commits]

poelmanc added a comment.

Just documenting here that I sent the following email to cfe-dev at lists.llvm.org:

> When parsing a named declaration with an equals sign with clang -std c++11/14, clang builds an initializer expression whose SourceRange covers from the variable name through the end of the initial value:
> 
>   std::string foo = "bar";
>               ^~~~~~~~~~~
> 
> When parsing the same code with clang -std c++17/2x, the initializer expression's SourceRange only includes the initial value itself, and not the variable name or the equals sign:
> 
>   std::string foo = "bar";
>                     ^~~~~
> 
> If the string is initialized using parentheses rather than an equals sign, in all of c++11/14/17/2x the initializer expression's SourceRange includes the variable name and both parentheses:
> 
>   std::string foo("bar");
>               ^~~~~~~~~~
> 
> This difference has broken clang-tidy's readability-remove-redundant-string for c++17 and c++2x, as described in at reviews.llvm.org/D69238 <https://reviews.llvm.org/D69238>. Is this SourceRange difference intentional, and if not does anyone have thoughts on how to make the SourceRange consistent across C++ standards? Thanks!
> 
> P.S. I've tried stepping through clang-tidy parsing the `std::string a = "";` line in `clang-tools-extra/test/clang-tidy/checkers/readability-redundant-string-init.cpp` with -std=c++11 and again with -std=c++17. In both cases `Sema::AddInitializerToDecl` seems to create a correct `InitializationKind` with the `Locations[0]` properly pointing to the start of the variable name. I'm not sure how or where that gets translated to the expression's SourceRange later on in some way that presumably differs between c++11 and c++17. If this SourceRange difference is unintentional and needs to be tracked down and fixed, any tips on where to look would be appreciated.

I didn't receive any email responses, I believe it prompted @NoQ to look this over and comment - thanks!


Repository:
  rCTE Clang Tools Extra

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69238/new/

https://reviews.llvm.org/D69238