Re: trace-cmd: Only add udis86 CFLAGS and LDFLAGS if it is found

[Patrick McLean <chutzpah@gentoo.org>]

On Wed, 24 Jul 2019 15:13:49 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> [ Patrick, I don't have udis86 on my machines, can you test to see if
>   this will include it if you do not set NO_UDIS86? ]
> 
> As we need to update both LDFLAGS and CFLAGS, move the test to see if
> udisc86 is installed to a variable, and then set NO_UDIS86 if it is
> not found. This way we do not need to test if it exists twice, nor
> have LDFLAGS set unconditionally.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204277
> 
> Reported-by: howaboutsynergy@pm.me
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
> diff --git a/Makefile b/Makefile
> index 0aa98517..e98535ea 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -136,9 +136,14 @@ export NO_PYTHON
>  test-build = $(if $(shell sh -c 'echo "$(1)" | \
>  	$(CC) -o /dev/null -c -x c - > /dev/null 2>&1 && echo y'),
> $2) 
> +UDIS86_AVAILABLE := $(call test-build,\#include <udis86.h>, y)
> +ifneq ($(UDIS86_AVAILABLE), y)

The value of UDIS86_AVAILABLE ends up having whitespace, so this line
always fails. If you change it to the line below, it works.
ifneq ($(strip $(UDIS86_AVAILABLE)), y)

> +NO_UDIS86 := 1
> +endif
> +
>  ifndef NO_UDIS86
>  # have udis86 disassembler library?
> -udis86-flags := $(call test-build,\#include <udis86.h>,-DHAVE_UDIS86
> -ludis86) +udis86-flags := -DHAVE_UDIS86 -ludis86
>  udis86-ldflags := -ludis86
>  endif # NO_UDIS86
>