Re: [PATCH] tools: perf: Avoid error message when building with no python installed

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Jul 28, 2015 at 01:49:12PM +0100, Pawel Moll wrote:
> On Mon, 2015-07-27 at 19:36 +0100, Jiri Olsa wrote:
> > > @@ -150,7 +150,7 @@ ifndef NO_LIBPYTHON
> > >    PYTHON2 := $(if $(call get-executable,python2),python2,python)
> > >    override PYTHON := $(call get-executable-or-default,PYTHON,$(PYTHON2))
> > >    PYTHON2_CONFIG := \
> > > -    $(if $(call get-executable,$(PYTHON)-config),$(PYTHON)-config,python-config)
> > > +    $(if $(PYTHON),$(if $(call get-executable,$(PYTHON)-config),$(PYTHON)-config,python-config))
> > >    override PYTHON_CONFIG := \
> > >      $(call get-executable-or-default,PYTHON_CONFIG,$(PYTHON2_CONFIG))
> > 
> > haven't tried, but seems like we want to add also the else part
> > to get default into PYTHON_CONFIG?
> > -    $(if $(PYTHON),$(if $(call get-executable,$(PYTHON)-config),$(PYTHON)-config,python-config))
> > +    $(if $(PYTHON),$(if $(call get-executable,$(PYTHON)-config),$(PYTHON)-config,python-config),python-config)
> 
> It's not strictly necessary, because the issue here is just executing
> "command -v -c" (followed by "onfig" :-), but of course it will still
> work.
> 
> > it fails anyway later either way, but seems like the 'python-config'
> > was the default case that was meant to fail later
> 
> Well, yes, I had the same impression. But at the same time
> get-executable-or-default is constructed in such a way that either of
> the variants must be a real executable:
> 
> --8<-----------
> # get-supplied-or-default-executable
> #
> # Usage: absolute-executable-path-or-empty = $(call get-executable-or-default,variable,default)
> #
> define get-executable-or-default
> $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
> endef
> _ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,$(2)))
> _gea_err  = $(if $(1),$(error Please set '$(1)' appropriately))
> --8<-----------
> 
> See? Both alternatives in the $(if $($(1)) monster do _ge_attempt... So
> one could say that the change may rather look like this (untested):
> 
> --8<-----------
> diff --git a/tools/perf/config/utilities.mak
> b/tools/perf/config/utilities.mak
> index 0ebef09..78135dc 100644
> --- a/tools/perf/config/utilities.mak
> +++ b/tools/perf/config/utilities.mak
> @@ -173,7 +173,7 @@ _ge-abspath = $(if $(is-executable),$(1))
>  # Usage: absolute-executable-path-or-empty = $(call
> get-executable-or-default,variable,default)
>  #
>  define get-executable-or-default
> -$(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
> +$(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(2))
>  endef
>  _ge_attempt = $(if $(get-executable),$(get-executable),$(call _gea_err,
> $(2)))
>  _gea_err  = $(if $(1),$(error Please set '$(1)' appropriately))

hum right.. looks like pythom is the only caller, nice

jirka