[Buildroot] [PATCH 1/3] Makefile: use absolute paths to BR2_EXTERNAL

[Yann E. MORIN <yann.morin.1998@free.fr>]

Arnoud, All,

On 2014-01-27 18:26 +0100, Arnout Vandecappelle spake thusly:
> On 22/01/14 21:59, Yann E. MORIN wrote:
> >+  _BR2_EXTERNAL = $(shell cd $(BR2_EXTERNAL) >/dev/null 2>&1 && pwd)
> >+  ifeq ($(_BR2_EXTERNAL),)
> >+    ifeq ($(patsubst /%,/,$(BR2_EXTERNAL)),/)
> >+      $(error BR2_EXTERNAL='$(BR2_EXTERNAL)' does not exist)
> >+    else
> >+      $(error BR2_EXTERNAL='$(BR2_EXTERNAL)' does not exist, relatively to $(TOPDIR))
> 
>  I don't think the limited explanation "relatively to $(TOPDIR)" warrants
> the additional complexity of patsubsting stuff.

Well, we want to tell the user why w edid not find his BR2_EXTERNAL.
And since it can be tricky to understand that a relative path is not
found, we do want to highlight that fact in the error message.

> >+    endif
> >+  endif
> >+  BR2_EXTERNAL := $(_BR2_EXTERNAL)
> 
>  AFAICS there is no need to have a separate _BR2_EXTERNAL, since we'll
> anyway error out if it is empty.

I used an intermediate, since I want to display the user-supplied path
in the error message, not the one we found (or did not find).

>  So, I'd propose:
> 
> override BR2_EXTERNAL := $(shell cd $(BR2_EXTERNAL) >/dev/null 2>&1 && pwd)
> ifeq ($(BR2_EXTERNAL),)
> 	$(error BR2_EXTERNAL directory '$(BR2_EXTERNAL)' does not exist)
> endif

Uh? In this case $(BR2_EXTERNAL) would be empty in the error message, no?

Regards,
Yann E. MORIN.

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