Re: [UNIKRAFT PATCH 2/3] support/build: Add build functions for clang and gcc check

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

On 21.11.20 17:34, Vlad-Andrei Badoiu wrote:
> We add have_gcc and have_clang. We modify gcc_version_ge to
> use have_gcc.
>
> Signed-off-by: Alice Suiu <alicesuiu17@xxxxxxxxx>
> Signed-off-by: Vlad-Andrei Badoiu <vlad_andrei.badoiu@xxxxxx>
> ---
>   support/build/Makefile.rules | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/support/build/Makefile.rules b/support/build/Makefile.rules
> index 9a5963fd..ecd409f0 100644
> --- a/support/build/Makefile.rules
> +++ b/support/build/Makefile.rules
> @@ -29,10 +29,20 @@ lc = $(subst A,a,$(subst B,b,$(subst C,c,$(subst 
> D,d,$(subst E,e,$(subst F,f,$(s
>   # upper case
>   uc = $(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst 
> f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst 
> l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst 
> r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst 
> x,X,$(subst y,Y,$(subst z,Z,$(1)))))))))))))))))))))))))))
>   
> +# test if GCC is set as a compiler
> +define have_gcc =
> +$(shell if [ $(CC) = gcc ] ; then echo y ; else echo n ; fi)
> +endef
> +
> +# test if CLANG is set as a compiler
> +define have_clang =
> +$(shell if [ $(CC) == clang ] ; then echo y ; else echo n ; fi)
I just found that use a double `=` for the clang check but a single `=` 
for the gcc check. In general, a single `=` should just work.
> +endef
> +
>   # test whether GCC version is greater than or equal to the minimum requirement
>   # gcc_version_ge $gcc_major,$gcc_minor
>   define gcc_version_ge =
> -$(shell if [ $(CC_VER_MAJOR) -gt $(1) ] || ([ $(CC_VER_MAJOR) -eq $(1) ] && [ 
> $(CC_VER_MINOR) -ge $(2) ]) ; then echo y ; fi)
> +$(shell if [ $(call have_gcc) = y ] ; then if [ $(CC_VER_MAJOR) -gt $(1) ] || ([ 
> $(CC_VER_MAJOR) -eq $(1) ] && [ $(CC_VER_MINOR) -ge $(2) ]) ; then echo y ; fi 
> ; else echo n ; fi)
>   endef
>   
Out of curiosity, I guess you also plan to add a command like 
`clang_version_ge`? ;-)
>   # print error and stop build when GCC version doesn't meet the minimum 
> requirement