Re: [PATCH] perf tools: Enable warnings through HOSTCFLAGS

[John Garry]

On 06/11/2021 19:27, Arnaldo Carvalho de Melo wrote:
> Em Sat, Oct 30, 2021 at 12:30:41AM +0800, John Garry escreveu:
> > The tools build system uses KBUILD_HOSTCFLAGS symbol for obvious purposes.
> >
> > However this is not set for anything under tools/
> >
> > As such, host tools apps built have no compiler warnings enabled.
> >
> > Declare HOSTCFLAGS for perf tools build, and also use that symbol in
> > declaration of host_c_flags. HOSTCFLAGS comes from EXTRA_WARNINGS, which
> > is independent of target platform/arch warning flags.
> >
> > Suggested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> > --
> > Using HOSTCFLAGS, as opposed to KBUILD_HOSTCFLAGS, is going opposite
> > direction to commit 96f14fe738b6 ("kbuild: Rename HOSTCFLAGS to
> > KBUILD_HOSTCFLAGS"), so would like further opinion from Laura and
> > Masahiro.
>
> Laura's redhat e-mail bouncedm updated it to her kernel.org one, Laura,
> Masahiro, would you please comment? Jiri?

Any opinion on this one? Shall I just resend ... ? or just apply it if 
no one cares too much :)

Thanks,
John

> - Arnaldo
>   
> > diff --git a/tools/build/Build.include b/tools/build/Build.include
> > index 2cf3b1bde86e..c2a95ab47379 100644
> > --- a/tools/build/Build.include
> > +++ b/tools/build/Build.include
> > @@ -99,7 +99,7 @@ cxx_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXX
> >   ###
> >   ## HOSTCC C flags
> >   
> > -host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(KBUILD_HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
> > +host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))
> >   
> >   # output directory for tests below
> >   TMPOUT = .tmp_$$$$
> > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > index 4a9baed28f2e..9b95ba09657f 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -17,6 +17,7 @@ detected     = $(shell echo "$(1)=y"       >> $(OUTPUT).config-detected)
> >   detected_var = $(shell echo "$(1)=$($(1))" >> $(OUTPUT).config-detected)
> >   
> >   CFLAGS := $(EXTRA_CFLAGS) $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
> > +HOSTCFLAGS := $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
> >   
> >   include $(srctree)/tools/scripts/Makefile.arch
> >   
> > @@ -211,6 +212,7 @@ endif
> >   ifneq ($(WERROR),0)
> >     CORE_CFLAGS += -Werror
> >     CXXFLAGS += -Werror
> > +  HOSTCFLAGS += -Werror
> >   endif
> >   
> >   ifndef DEBUG
> > @@ -292,6 +294,9 @@ CXXFLAGS += -ggdb3
> >   CXXFLAGS += -funwind-tables
> >   CXXFLAGS += -Wno-strict-aliasing
> >   
> > +HOSTCFLAGS += -Wall
> > +HOSTCFLAGS += -Wextra
> > +
> >   # Enforce a non-executable stack, as we may regress (again) in the future by
> >   # adding assembler files missing the .GNU-stack linker note.
> >   LDFLAGS += -Wl,-z,noexecstack
> > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> > index a3966f290297..8ca656aa8b06 100644
> > --- a/tools/perf/Makefile.perf
> > +++ b/tools/perf/Makefile.perf
> > @@ -226,7 +226,7 @@ else
> >   endif
> >   
> >   export srctree OUTPUT RM CC CXX LD AR CFLAGS CXXFLAGS V BISON FLEX AWK
> > -export HOSTCC HOSTLD HOSTAR
> > +export HOSTCC HOSTLD HOSTAR HOSTCFLAGS
> >   
> >   include $(srctree)/tools/build/Makefile.include
> >   
> > --
> > 2.17.1