README: Add link to merged clang-tidy check

[mikecrowe]

A much-improved version of the main clang-tidy-fmt check for converting printf and fprintf has landed in upstream LLVM. It converts to std::print by default, but can be configured to convert to fmt::print instead. It makes more sense for the README to point to that version instead now.

[mikecrowe]

Since you're the world experts on the format specification syntax, it would
be lovely if you could also have a look at the test cases for the check at
https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp
to see if there are any glaring omissions or mistakes.

Thanks!

[vitaut]

Thank you!

In https://github.com/llvm/llvm-project/blob/fc37f717770acdfe5504bb9b969a01bb16a187f9/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp#L339C34-L339C36
why is the format string "{} {{[{][{]}}}}" and not `"{} {{}}"?

Also note that the order of dynamic width/precision and the argument it applies to should be reversed in https://github.com/llvm/llvm-project/blob/fc37f717770acdfe5504bb9b969a01bb16a187f9/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp#L1025 and elsewhere.

[mikecrowe]

In https://github.com/llvm/llvm-project/blob/fc37f717770acdfe5504bb9b969a01bb16a187f9/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp#L339C34-L339C36
why is the format string "{} {{[{][{]}}}}" and not `"{} {{}}"?

LLVM FileCheckexpects anything in {{ and }} to be a regex. So, to match literal {{}} I need to write a regex that matches it and enclose it in those characters. The documentation for FileCheck says:

In the rare case that you want to match double braces explicitly from the input, you can use something ugly like {{[}][}]}} as your pattern.

which is almost what I needed.

Also note that the order of dynamic width/precision and the argument it applies to should be reversed in https://github.com/llvm/llvm-project/blob/fc37f717770acdfe5504bb9b969a01bb16a187f9/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp#L1025 and elsewhere.

Thanks for the review. I shall try to implement that - if I can fathom out how!

[mikecrowe]

Also note that the order of dynamic width/precision and the argument it applies to should be reversed in https://github.com/llvm/llvm-project/blob/fc37f717770acdfe5504bb9b969a01bb16a187f9/clang-tools-extra/test/clang-tidy/checkers/modernize/use-std-print.cpp#L1025 and elsewhere.

Hopefully fixed by D154283. Thanks for pointing out the flaw. It was easier to fix than I expected.