github.com/westcoastroms/westcoastroms-build@v0.0.0-20190928114312-2350e5a73030/build/make/Changes.md (about)

     1  # Build System Changes for Android.mk Writers
     2  
     3  ## Deprecating / obsoleting envsetup.sh variables in Makefiles
     4  
     5  It is not required to source envsetup.sh before running a build. Many scripts,
     6  including a majority of our automated build systems, do not do so. Make will
     7  transparently make every environment variable available as a make variable.
     8  This means that relying on environment variables only set up in envsetup.sh will
     9  produce different output for local users and scripted users.
    10  
    11  Many of these variables also include absolute path names, which we'd like to
    12  keep out of the generated files, so that you don't need to do a full rebuild if
    13  you move the source tree.
    14  
    15  To fix this, we're marking the variables that are set in envsetup.sh as
    16  deprecated in the makefiles. This will trigger a warning every time one is read
    17  (or written) inside Kati. Once all the warnings have been removed for a
    18  particular variable, we'll switch it to obsolete, and any references will become
    19  errors.
    20  
    21  ### envsetup.sh variables with make equivalents
    22  
    23  | instead of                                                   | use                  |
    24  |--------------------------------------------------------------|----------------------|
    25  | OUT {#OUT}                                                   | OUT_DIR              |
    26  | ANDROID_HOST_OUT {#ANDROID_HOST_OUT}                         | HOST_OUT             |
    27  | ANDROID_PRODUCT_OUT {#ANDROID_PRODUCT_OUT}                   | PRODUCT_OUT          |
    28  | ANDROID_HOST_OUT_TESTCASES {#ANDROID_HOST_OUT_TESTCASES}     | HOST_OUT_TESTCASES   |
    29  | ANDROID_TARGET_OUT_TESTCASES {#ANDROID_TARGET_OUT_TESTCASES} | TARGET_OUT_TESTCASES |
    30  
    31  All of the make variables may be relative paths from the current directory, or
    32  absolute paths if the output directory was specified as an absolute path. If you
    33  need an absolute variable, convert it to absolute during a rule, so that it's
    34  not expanded into the generated ninja file:
    35  
    36  ``` make
    37  $(PRODUCT_OUT)/gen.img: my/src/path/gen.sh
    38  	export PRODUCT_OUT=$$(cd $(PRODUCT_OUT); pwd); cd my/src/path; ./gen.sh -o $${PRODUCT_OUT}/gen.img
    39  ```
    40  
    41  ### ANDROID_BUILD_TOP  {#ANDROID_BUILD_TOP}
    42  
    43  In Android.mk files, you can always assume that the current directory is the
    44  root of the source tree, so this can just be replaced with '.' (which is what
    45  $TOP is hardcoded to), or removed entirely. If you need an absolute path, see
    46  the instructions above.
    47  
    48  ### Stop using PATH directly  {#PATH}
    49  
    50  This isn't only set by envsetup.sh, but it is modified by it. Due to that it's
    51  rather easy for this to change between different shells, and it's not ideal to
    52  reread the makefiles every time this changes.
    53  
    54  In most cases, you shouldn't need to touch PATH at all. When you need to have a
    55  rule reference a particular binary that's part of the source tree or outputs,
    56  it's preferrable to just use the path to the file itself (since you should
    57  already be adding that as a dependency).
    58  
    59  Depending on the rule, passing the file path itself may not be feasible due to
    60  layers of unchangable scripts/binaries. In that case, be sure to add the
    61  dependency, but modify the PATH within the rule itself:
    62  
    63  ``` make
    64  $(TARGET): myscript my/path/binary
    65  	PATH=my/path:$$PATH myscript -o $@
    66  ```
    67  
    68  ### Stop using PYTHONPATH directly  {#PYTHONPATH}
    69  
    70  Like PATH, this isn't only set by envsetup.sh, but it is modified by it. Due to
    71  that it's rather easy for this to change between different shells, and it's not
    72  ideal to reread the makefiles every time.
    73  
    74  The best solution here is to start switching to Soong's python building support,
    75  which packages the python interpreter, libraries, and script all into one file
    76  that no longer needs PYTHONPATH. See fontchain_lint for examples of this:
    77  
    78  * [external/fonttools/Lib/fontTools/Android.bp] for python_library_host
    79  * [frameworks/base/Android.bp] for python_binary_host
    80  * [frameworks/base/data/fonts/Android.mk] to execute the python binary
    81  
    82  If you still need to use PYTHONPATH, do so within the rule itself, just like
    83  path:
    84  
    85  ``` make
    86  $(TARGET): myscript.py $(sort $(shell find my/python/lib -name '*.py'))
    87  	PYTHONPATH=my/python/lib:$$PYTHONPATH myscript.py -o $@
    88  ```
    89  ### Stop using PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE directly {#PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE}
    90  
    91  Specify Framework Compatibility Matrix Version in device manifest by adding a `target-level`
    92  attribute to the root element `<manifest>`. If `PRODUCT_COMPATIBILITY_MATRIX_LEVEL_OVERRIDE`
    93  is 26 or 27, you can add `"target-level"="1"` to your device manifest instead.
    94  
    95  ### Stop using USE_CLANG_PLATFORM_BUILD {#USE_CLANG_PLATFORM_BUILD}
    96  
    97  Clang is the default and only supported Android compiler, so there is no reason
    98  for this option to exist.
    99  
   100  ### Other envsetup.sh variables  {#other_envsetup_variables}
   101  
   102  * ANDROID_TOOLCHAIN
   103  * ANDROID_TOOLCHAIN_2ND_ARCH
   104  * ANDROID_DEV_SCRIPTS
   105  * ANDROID_EMULATOR_PREBUILTS
   106  * ANDROID_PRE_BUILD_PATHS
   107  
   108  These are all exported from envsetup.sh, but don't have clear equivalents within
   109  the makefile system. If you need one of them, you'll have to set up your own
   110  version.
   111  
   112  
   113  [build/soong/Changes.md]: https://android.googlesource.com/platform/build/soong/+/master/Changes.md
   114  [external/fonttools/Lib/fontTools/Android.bp]: https://android.googlesource.com/platform/external/fonttools/+/master/Lib/fontTools/Android.bp
   115  [frameworks/base/Android.bp]: https://android.googlesource.com/platform/frameworks/base/+/master/Android.bp
   116  [frameworks/base/data/fonts/Android.mk]: https://android.googlesource.com/platform/frameworks/base/+/master/data/fonts/Android.mk