[Bug fortran/121759] Windows/MinGW: formatted reads lose decimal digits after binary stream read

[Yohann.Vautrin@nrc-cnrc.gc.ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121759

Yohann Vautrin <Yohann.Vautrin@nrc-cnrc.gc.ca> changed:

           What    |Removed                     |Added
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                 CC|                            |Yohann.Vautrin@nrc-cnrc.gc.
                   |                            |ca

--- Comment #6 from Yohann Vautrin <Yohann.Vautrin@nrc-cnrc.gc.ca> ---
Created attachment 65153
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65153&action=edit
Locale-handling bug reproducer

Environment: Windows 11 23H2, amd64

- Install MSYS2
- Open Settings / Time & language / Language & region and set Regional format
to, e.g., "French (Canada)"
- Start a MSYS2 UCRT64 environment with gfortran installed with pacman (package
name is mingw-w64-ucrt-x86_64-gcc-libgfortran, version is 16.1.0-5 currently)
- Compile the attached reproducer with gfortran -Wall -Wextra -pedantic
reproducer.f90 and run it

If the bug is reproduced, the program will output this, followed by a
backtrace:
Before unformatted I/O:
  - Expected:  0.10000000000000001
  - Parsed  :  0.10000000000000001
 After unformatted I/O:
  - Expected:  0.10000000000000001
  - Parsed  :   0.0000000000000000
ERROR STOP 2