问题
Fortran 2008 added a new procedure called COMPILER_OPTIONS() which according to GNU documentation should return a string with the options used for compiling the file. According to Fortran 2003 status wiki, almost all compilers including GNU and PGI seem to support this feature.
I created a simple program COMPILER_OPTIONS.f08 shown below
use iso_fortran_env
print '(4a)', 'This file was compiled by using the options ', compiler_options()
end
Here are my results from gfortran and pgfortran
Gfortran 5.4 with no compile time options
$ gfortran COMPILER_OPTIONS.f08 && ./a.out
This file was compiled by using the options -mtune=generic -march=x86-64
Gfortran 5.4 with -O3 passed at compile time
$ gfortran -O3 COMPILER_OPTIONS.f08 && ./a.out
This file was compiled by using the options -mtune=generic -march=x86-64 -O3
PGI 17.4 with no option passed at compile time
$ pgfortran COMPILER_OPTIONS.f08 && ./a.out
This file was compiled by using the options COMPILER_OPTIONS.f08
PGI 17.4 with -O3 passed at compile time
$ pgfortran -O3 COMPILER_OPTIONS.f08 && ./a.out
This file was compiled by using the options COMPILER_OPTIONS.f08 -O3 -Mvect=sse -Mcache_align -Mpre
Given the above output, I have following questions
- What is COMPILER_OPTIONS() procedure expected to return as per Fortran 2008?
- What is the status of support across different compilers?
EDIT : Changed flag to -O3 (Optimization Level 3) from -o3 (Output file 3). Thanks to the feedback from Pierre and francescalus.
回答1:
Fortran 2008 describes the function as (13.8.2.6):
Processor-dependent string describing the options that controlled the program translation phase.
This function returns a "default character scalar with processor-dependent length."
That's an awful lot of freedom for a compiler. There's no indication from the results presented here to suggest any non-compliance.
来源：https://stackoverflow.com/questions/46464763/what-should-compiler-options-return-in-fortran