commit f65a6dfd635dd389434090681b5fc5a65ec5f91d
author Dan Pasanen <dan.pasanen@gmail.com> Sun Feb 18 22:13:05 2018 -0600
committer Dan Pasanen <dan.pasanen@gmail.com> Mon Feb 19 04:20:53 2018 +0000
tree 6088de3a7fc39eedb76943559722191fc7187236
parent ae509e410cda5996cf9e54c4d65ae98d86d8f18f

kernel: fix ccache variable sanitation for clang builds

* When using "?=", expansion doesn't happen right away, so the ccache
  variable is sanitized before KERNEL_CC gets expanded and no ccache
  is ever used for clang builds.

* With ":=", expansion happens immediately. So let's manually check
  if KERNEL_CC is already set somewhere else to determine whether or
  not we should set it ourselves using ":=".

Change-Id: I8a61767606a4f3d4c6ba88c68b10fd2e11783406

build/tasks/kernel.mk

diff --git a/build/tasks/kernel.mk b/build/tasks/kernel.mk
index c4dcf6e..4466d1b 100644
--- a/build/tasks/kernel.mk
+++ b/build/tasks/kernel.mk
@@ -257,7 +257,9 @@
 
 ifeq ($(TARGET_KERNEL_CLANG_COMPILE),true)
     KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(KERNEL_TOOLCHAIN_PATH)"
-    KERNEL_CC ?= CC="$(ccache) $(TARGET_KERNEL_CLANG_PATH)/clang"
+    ifeq ($(KERNEL_CC),)
+        KERNEL_CC := CC="$(ccache) $(TARGET_KERNEL_CLANG_PATH)/clang"
+    endif
 else
     KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(ccache) $(KERNEL_TOOLCHAIN_PATH)"
 endif