[Bug preprocessor/82176] New: Feature request: replace __FILE__ with file's basename instead its full name

["f.hollerer at gmx dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82176

            Bug ID: 82176
           Summary: Feature request: replace __FILE__ with file's basename
                    instead its full name
           Product: gcc
           Version: 6.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: f.hollerer at gmx dot net
  Target Milestone: ---

Actually, this is a feature request, not a bug report.

It would be great to have a command line option to tell the
preprocessor to replace __FILE__ with the basename of a file, not the
complete name with relative or absolute path components as passed to
the preprocessor / compiler when invoked.

Reason is to minimise the amount of FLASH / code memory required for
the strings.

Explanation:

I am using arm-none-eabi-gcc version 6.3.1 downloaded from
https://developer.arm.com/ to build fora Cortex-M4 with 32 kB code
memory. Unfortunately, the cmake Build system I am using always passes
the absolute file path to the compiler, furthermore the driver code
provided by the chip vendor uses allot of assert()s.

I don't want to turn off assert()s completely, but with __FILE__ being
replaced with the full file name blows up my firmware image.
Restricting it to the file's basename would bring the image back to
reasonable size, by still providing good error messages.

After consutling google for a while, I found that other compiler toolchains
provide this feature. E.g. IAR:

https://www.iar.com/support/tech-notes/general/avoiding-full-paths-in-the-output-file/

Therefore, I think it is a feature of common interest, especially in the
embedded world.

Thanks & Best regards,

Franz Hollerer