ccache no longer works for NCS in Windows with newer versions of ccache

[Burt]

There was no problem when the current version of ccache was 4.6.1. However, the current version of ccache, 4.10.2, behaves differently with the --specs option. It will do nothing at all with NCS. To correct this, I make this change

diff --git a/cmake/modules/ccache.cmake b/cmake/modules/ccache.cmake
index c1d41d6b9e4..14b9b683519 100644
--- a/cmake/modules/ccache.cmake
+++ b/cmake/modules/ccache.cmake
@@ -9,7 +9,7 @@ if(USE_CCACHE STREQUAL "0")
else()
find_program(CCACHE_FOUND ccache)
if(CCACHE_FOUND)
- set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
+ set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "ccache ignore_options=--specs=picolibc.specs")
set_property(GLOBAL PROPERTY RULE_LAUNCH_LINK ccache)
endif()
endif()

Thank you for any possible correction. I guess in the Linux case you include ccache in the Zephyr toolchain and it is a version that works.

Burt Silverman

[Charlie]

Hi Burt,

Thank you for sharing your knowledge. I found that Windows indeed does not have ccache installed by default.

I’m not entirely sure why Linux-like systems include it while Windows does not. However, I believe the Issues · zephyrproject-rtos/zephyr  would be a better place to discuss this topic, as it relates to zephyr/scripts/west_commands/build.py.

Best regards,

Charlie

[Burt]

Hi Charlie,

I agree with you up to where you say that this relates to zephyr/scripts/west_commands/build.py. Perhaps you are conflating ccache with the CMake cache that is referenced in build.py.

A more interesting question would be why we find for example ncs/toolchains/e9dba88316/usr/bin/ccache in the Linux case but do not find for example a C:\ncs\toolchains\c57af46cb7\usr\bin\ccache.exe in the Windows case. Are not the contents of the various ncs/toolchains put together by NS based on input from zephyr but customized by NS? I see this as a primarily NS issue at this time, as you could include the same version of ccache in the Windows toolchain as the one which works for Linux; granted if you put the latest version of ccache into either Linux or Windows then we'd have to ask Zephyr to fix zephyr/cmake/modules/ccache.cmake. There is an argument for either method, I'd say, but currently your Windows users are at a disadvantage because most probably are not looking so closely to see that ccache is either absent or not doing its job.

Burt