mikecrowe added inline comments.
================
Comment at:
clang-tools-extra/docs/clang-tidy/checks/modernize/use-std-print.rst:79
+
+.. option:: StrictMode
+
----------------
It turns out that absl::PrintF and absl::FPrintF work like std::format,
fmt::printf, etc. and use the signedness of the argument rather than the
signedness indicated in the format string to determine how to format the
number. In other words:
`unsigned int ui = 0xffffffff; absl::PrintF("%d\n", ui);` yields `4294967295`
(see https://godbolt.org/z/dYcbehxP9 ), so the casts that StrictMode adds would
change the behaviour of the converted code.
I can think of several ways around this:
1. Update the documentation to explain this, recommending not to use StrictMode
when converting Abseil functions.
2. Remove built-in support for Abseil functions from this check. Anyone wishing
to convert them can do so via the customisation features, and can choose not to
use StrictMode. (This could be documented here.)
3. Teach the code to recognise whether the arguments is being passed as a
C-style variable argument list or as fully-typed arguments to a templated
function and make StrictMode only add the casts for the former. (I've not
investigated how feasible this is.)
4. Treat the known Abseil functions in this check differently by name and
disable the casting behaviour. This means that conversion from fmt::printf via
the customisation mechanism wouldn't automatically get that behaviour.
As someone who doesn't use Abseil I'm inclined towards option 2, with the
possibility of implementing option 3 in a separate commit later. I'm not
particularly keen on the other two options.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D149280/new/
https://reviews.llvm.org/D149280
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