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| author | Dan Willemsen <dwillemsen@google.com> | 2020-01-14 10:56:53 -0800 |
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| committer | Dan Willemsen <dwillemsen@google.com> | 2020-01-14 15:08:41 -0800 |
| commit | 2bfffb9f48a78de12faf5da77424c0cecb70d6eb (patch) | |
| tree | 5eb36de88d02084858984c2fdb3e1304cdff7db8 | |
| parent | 997661002af1282d938e88c3c723037e42e5d283 (diff) | |
| download | platform_build-2bfffb9f48a78de12faf5da77424c0cecb70d6eb.tar.gz platform_build-2bfffb9f48a78de12faf5da77424c0cecb70d6eb.tar.bz2 platform_build-2bfffb9f48a78de12faf5da77424c0cecb70d6eb.zip | |
Document the m4 prebuilts
Test: view in gitiles
Change-Id: I2defdb433313fb6744b09685d289e16d094cffdc
| -rw-r--r-- | Changes.md | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Changes.md b/Changes.md index 04e0161181..70e338cee6 100644 --- a/Changes.md +++ b/Changes.md @@ -1,5 +1,20 @@ # Build System Changes for Android.mk Writers +## `m4` is not available on `$PATH` + +There is a prebuilt of it available in prebuilts/build-tools, and a make +variable `M4` that contains the path. + +Beyond the direct usage, whenever you use bison or flex directly, they call m4 +behind the scene, so you must set the M4 environment variable (and depend upon +it for incremental build correctness): + +``` +$(intermediates)/foo.c: .KATI_IMPLICIT_OUTPUTS := $(intermediates)/foo.h +$(intermediates)/foo.c: $(LOCAL_PATH)/foo.y $(M4) $(BISON) $(BISON_DATA) + M4=$(M4) $(BISON) ... +``` + ## Rules executed within limited environment With `ALLOW_NINJA_ENV=false` (soon to be the default), ninja, and all the |