[PATCH v2 02/16] buildman/toolchain.py: set CROSS_COMPILE only if self.cross is set

[Jerome Forissier]

In MakeEnvironment(), CROSS_COMPILE is defined to be self.cross (with
or without a full path), optionally prefixed by the toolchain wrapper
defined in ~/.buildman. This is fine when self.cross is not empty, but
it doesn't make sense when it is:
- Either there is no wrapper and we end up with an empty CROSS_COMPILE
which is the same as not defining it (the host compiler will be used),
- Or there is a wrapper and CROSS_COMPILE will contain only the wrapper
which obviously is not a valid compiler, hence an error.

Test case:

 $ sudo apt install ccache
 $ grep -q toolchain-wrapper ~/.buildman || \
     printf "[toolchain-wrapper]\nwrapper = ccache\n" >>~/.buildman
 $ make mrproper
 $ ./tools/buildman/buildman sandbox_noinst
 $ ./tools/buildman/buildman sandbox_noinst
 Building current source for 1 boards (1 thread, 24 jobs per thread)
    sandbox:  +   sandbox_noinst
 +In file included from boot/bootmeth_efi.c:16:
 +include/efi_default_filename.h:20:15: error: operator '==' has no left operand
 +   20 | #if HOST_ARCH == HOST_ARCH_X86_64
 +      |               ^~
 [...]

Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
---
 tools/buildman/toolchain.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/buildman/toolchain.py b/tools/buildman/toolchain.py
index 324ad0e082..ff987a9eea 100644
--- a/tools/buildman/toolchain.py
+++ b/tools/buildman/toolchain.py
@@ -201,10 +201,10 @@ class Toolchain:
         if self.override_toolchain:
             # We'll use MakeArgs() to provide this
             pass
-        elif full_path:
+        elif full_path and self.cross:
             env[b'CROSS_COMPILE'] = tools.to_bytes(
                 wrapper + os.path.join(self.path, self.cross))
-        else:
+        elif self.cross:
             env[b'CROSS_COMPILE'] = tools.to_bytes(wrapper + self.cross)
             env[b'PATH'] = tools.to_bytes(self.path) + b':' + env[b'PATH']
 
-- 
2.40.1