https://sourceware.org/bugzilla/show_bug.cgi?id=25572
Bug ID: 25572
Summary: /dev/null should be excluded from 'files are the same'
check
Product: binutils
Version: 2.35 (HEAD)
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: binutils
Assignee: unassigned at sourceware dot org
Reporter: masahiroy at kernel dot org
Target Milestone: ---
Hi.
I think using /dev/null for both input and output
is useful, but the assembler emits this warning:
$ gcc -c -x assembler /dev/null -o /dev/null
Assembler messages:
Fatal error: The input '/dev/null' and output '/dev/null' files are the same
This is especially useful to check whether
a particular flag is supported or not.
$ gcc -Wa,<some-assembler-flag> -c -x assembler /dev/null -o /dev/null
or
$ as <some-assembler-flag> /dev/null -o /dev/null
Then, check the exit code.
This technique is widely used in the Linux kernel build system.
However, with the current binutils,
this always exits with 1 with the 'files are the same' warning.
We could work around it by using /dev/zero
as a data sink, but this looks a bit strange.
$ gcc -Wa,<some-assembler-flag> -c -x assembler /dev/null -o /dev/zero
This was reported here
https://patchwork.kernel.org/patch/11347227/
I think device files should be excluded from the
same-file check.
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