python/python3: globalize *.pyc files compilation

Currently, each python package (be it the python interpreter package
itself or external python modules) is responsible for compiling its
.py into .pyc files. Unfortunately, this is not ideal as some packages
only install .py files without compiling them into .pyc files. In this
case, if the Buildroot configuration specifies to keep only the .pyc
files, the .py files are removed and lost.

To address this, this commit changes the logic by making the
compilation of .pyc files a global operation: the python interpreter
packages register a target finalize hook that is in charge of
compiling all installed .py files.

The *.pyc generation on a per package basis is disabled in the
python-package infrastructure by passing the "--no-compile" option to
setup.py.

The *.pyc generation for the Python interpreter internal modules is
disabled through --disable-pyc-build configure option.

A small helper script is used to perform the compilation, the purpose
of this script is to abort the compilation process if one of the .py
file cannot be compiled. It has been provided by Samuel Martin and
integrated into this commit.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Samuel Martin <s.martin49@gmail.com>
[Thomas:
 - rework for python 3.5
 - integrate Samuel proposal that allows to detect compilation
   failures.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/pkg-python.mk

@@ -253,7 +253,7 @@ ifndef $(2)_INSTALL_TARGET_CMDS
 define $(2)_INSTALL_TARGET_CMDS
 	(cd $$($$(PKG)_BUILDDIR)/; \
 		$$($$(PKG)_BASE_ENV) $$($$(PKG)_ENV) \
-		$$($(2)_PYTHON_INTERPRETER) setup.py install \
+		$$($(2)_PYTHON_INTERPRETER) setup.py install --no-compile \
 		$$($$(PKG)_BASE_INSTALL_TARGET_OPTS) \
 		$$($$(PKG)_INSTALL_TARGET_OPTS))
 endef

package/python/python.mk

@@ -143,7 +143,8 @@ PYTHON_CONF_OPTS += \
 	--disable-tk		\
 	--disable-nis		\
 	--disable-dbm		\
-	--disable-pyo-build
+	--disable-pyo-build	\
+	--disable-pyc-build
 
 # This is needed to make sure the Python build process doesn't try to
 # regenerate those files with the pgen program. Otherwise, it builds
@@ -217,6 +218,17 @@ PYTHON_PATH = $(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR)/sysconfigdata/
 $(eval $(autotools-package))
 $(eval $(host-autotools-package))
 
+define PYTHON_CREATE_PYC_FILES
+	PYTHONPATH="$(PYTHON_PATH)" \
+	$(HOST_DIR)/usr/bin/python$(PYTHON_VERSION_MAJOR) \
+		support/scripts/pycompile.py \
+		$(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR)
+endef
+
+ifeq ($(BR2_PACKAGE_PYTHON_PYC_ONLY)$(BR2_PACKAGE_PYTHON_PY_PYC),y)
+TARGET_FINALIZE_HOOKS += PYTHON_CREATE_PYC_FILES
+endif
+
 ifeq ($(BR2_PACKAGE_PYTHON_PYC_ONLY),y)
 define PYTHON_REMOVE_PY_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR) -name '*.py' -print0 | \
@@ -225,6 +237,8 @@ endef
 TARGET_FINALIZE_HOOKS += PYTHON_REMOVE_PY_FILES
 endif
 
+# Normally, *.pyc files should not have been compiled, but just in
+# case, we make sure we remove all of them.
 ifeq ($(BR2_PACKAGE_PYTHON_PY_ONLY),y)
 define PYTHON_REMOVE_PYC_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR) -name '*.pyc' -print0 | \

package/python3/python3.mk

@@ -78,10 +78,6 @@ ifeq ($(BR2_PACKAGE_PYTHON3_PYC_ONLY),y)
 PYTHON3_CONF_OPTS += --enable-old-stdlib-cache
 endif
 
-ifeq ($(BR2_PACKAGE_PYTHON3_PY_ONLY),y)
-PYTHON3_CONF_OPTS += --disable-pyc-build
-endif
-
 ifeq ($(BR2_PACKAGE_PYTHON3_SQLITE),y)
 PYTHON3_DEPENDENCIES += sqlite
 else
@@ -135,7 +131,8 @@ PYTHON3_CONF_OPTS += \
 	--disable-lib2to3	\
 	--disable-tk		\
 	--disable-nis		\
-	--disable-idle3
+	--disable-idle3		\
+	--disable-pyc-build
 
 # Python builds two tools to generate code: 'pgen' and
 # '_freeze_importlib'. Unfortunately, for the target Python, they are
@@ -212,6 +209,17 @@ PYTHON3_PATH = $(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR)/sysconfigdat
 $(eval $(autotools-package))
 $(eval $(host-autotools-package))
 
+define PYTHON3_CREATE_PYC_FILES
+	PYTHONPATH="$(PYTHON3_PATH)" \
+	$(HOST_DIR)/usr/bin/python$(PYTHON3_VERSION_MAJOR) \
+		support/scripts/pycompile.py \
+		$(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR)
+endef
+
+ifeq ($(BR2_PACKAGE_PYTHON3_PYC_ONLY)$(BR2_PACKAGE_PYTHON3_PY_PYC),y)
+TARGET_FINALIZE_HOOKS += PYTHON3_CREATE_PYC_FILES
+endif
+
 ifeq ($(BR2_PACKAGE_PYTHON3_PYC_ONLY),y)
 define PYTHON3_REMOVE_PY_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR) -name '*.py' -print0 | \
@@ -220,6 +228,8 @@ endef
 TARGET_FINALIZE_HOOKS += PYTHON3_REMOVE_PY_FILES
 endif
 
+# Normally, *.pyc files should not have been compiled, but just in
+# case, we make sure we remove all of them.
 ifeq ($(BR2_PACKAGE_PYTHON3_PY_ONLY),y)
 define PYTHON3_REMOVE_PYC_FILES
 	find $(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR) -name '*.pyc' -print0 | \

support/scripts/pycompile.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+# Wrapper for python2 and python3 around compileall to raise exception
+# when a python byte code generation failed.
+#
+# Inspired from:
+#   http://stackoverflow.com/questions/615632/how-to-detect-errors-from-compileall-compile-dir
+
+from __future__ import print_function
+import sys
+import py_compile
+import compileall
+
+class ReportProblem:
+    def __nonzero__(self):
+        type, value, traceback = sys.exc_info()
+        if type is not None and issubclass(type, py_compile.PyCompileError):
+            print("Cannot compile %s" %value.file)
+            raise value
+        return 1
+
+report_problem = ReportProblem()
+
+compileall.compile_dir(sys.argv[1], quiet=report_problem)