mariadb/cmake/do_abi_check.cmake
Otto Kekäläinen b7d87bf0a9 MDEV-20392: Skip ABI check if 'diff' is not found
Not all environments have 'diff' installed. Most notably CentOS 8
does not have diff out-of-the-box. Thus users running 'cmake .' and
'make' would fail to build MariaDB, and they would think the error
was in ABI incompatibilities due to the error message emitted by CMake
when in reality simply 'diff' was missing.

This fixes it and makes the developer experience better by simply skipping
the diffing if 'diff' is not found.

## Proof

Running in a clean CentOS 8 container.

### Before

```
$ cmake .
...
-- Looking for cpuid.h
-- Looking for cpuid.h - found
-- Looking for x86intrin.h
-- Looking for x86intrin.h - found
-- Looking for event.h
-- Looking for event.h - not found
-- Configuring done
-- Generating done
-- Build files have been written to: /build

$ make
Scanning dependencies of target abi_check
CMake Error at cmake/do_abi_check.cmake:82 (MESSAGE):
  ABI check found difference between /build/include/mysql/plugin_audit.h.pp
  and /build/abi_check.out

make[2]: *** [CMakeFiles/abi_check.dir/build.make:57: CMakeFiles/abi_check] Error 1
make[1]: *** [CMakeFiles/Makefile2:168: CMakeFiles/abi_check.dir/all] Error 2
make: *** [Makefile:163: all] Error 2

$ yum install -y diffutils
...
Installed:
  diffutils-3.6-6.el8.x86_64
Complete!

$ make
[  0%] Built target abi_check
Scanning dependencies of target INFO_BIN
[  0%] Built target INFO_BIN
Scanning dependencies of target INFO_SRC
[  0%] Built target INFO_SRC
Scanning dependencies of target wsrep_api_v26
[  0%] Building C object wsrep-lib/wsrep-API/CMakeFiles/wsrep_api_v26.dir/v26/wsrep_dummy.c.o
[  0%] Building C object wsrep-lib/wsrep-API/CMakeFiles/wsrep_api_v26.dir/v26/wsrep_gtid.c.o
[  0%] Building C object wsrep-lib/wsrep-API/CMakeFiles/wsrep_api_v26.dir/v26/wsrep_loader.c.o
[  0%] Building C object wsrep-lib/wsrep-API/CMakeFiles/wsrep_api_v26.dir/v26/wsrep_uuid.c.o
[  0%] Linking C static library libwsrep_api_v26.a
[  0%] Built target wsrep_api_v26
```

### After

```
$ make
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_audit.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_ftparser.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/psi/psi_abi_v1.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/psi/psi_abi_v2.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/client_plugin.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_auth.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_password_validation.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_encryption.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_data_type.h skipped.
Command 'diff' not found. ABI check for /build/server/include/mysql/plugin_function.h skipped.
[  0%] Built target abi_check
[  0%] Built target INFO_SRC
[  0%] Built target INFO_BIN
[  0%] Built target wsrep_api_v26
[  0%] Building CXX object wsrep-lib/src/CMakeFiles/wsrep-lib.dir/server_state.cpp.o
```

If diff is installed, those warnings are simply not shown. Builds pass
without the need to install 'diff'.
2021-06-18 08:18:13 +10:00

89 lines
3.6 KiB
CMake

# Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA
#
# Rules for checking that the abi/api has not changed.
#
# The following steps are followed in the do_abi_check rule below
#
# 1) Generate preprocessor output for the files that need to
# be tested for abi/api changes. use -nostdinc to prevent
# generation of preprocessor output for system headers. This
# results in messages in stderr saying that these headers
# were not found. Redirect the stderr output to /dev/null
# to prevent seeing these messages.
# 2) sed the output to
# 2.1) remove blank lines and lines that begin with "# "
# 2.2) When gcc -E is run on the Mac OS and solaris sparc platforms it
# introduces a line of output that shows up as a difference between
# the .pp and .out files. Remove these OS specific preprocessor text
# inserted by the preprocessor.
# 3) diff the generated file and the canons (.pp files already in
# the repository).
# 4) delete the .out file that is generated.
#
# If the diff fails, the generated file is not removed. This will
# be useful for analysis of ABI differences (e.g. using a visual
# diff tool).
#
# A ABI change that causes a build to fail will always be accompanied
# by new canons (.out files). The .out files that are not removed will
# be replaced as the new .pp files.
#
# e.g. If include/mysql/plugin.h has an ABI change then this rule would
# leave a <build directory>/abi_check.out file.
#
# A developer with a justified API change will then do a
# mv <build directory>/abi_check.out include/mysql/plugin.pp
# to replace the old canons with the new ones.
#
SET(abi_check_out ${BINARY_DIR}/abi_check.out)
FOREACH(file ${ABI_HEADERS})
GET_FILENAME_COMPONENT(header_basename ${file} NAME)
SET(tmpfile ${BINARY_DIR}/${header_basename}.pp.tmp)
EXECUTE_PROCESS(
COMMAND ${COMPILER}
-E -nostdinc -DMYSQL_ABI_CHECK -D__cplusplus
-I${SOURCE_DIR}/include
-I${BINARY_DIR}/include -I${SOURCE_DIR}/include/mysql -I${SOURCE_DIR}/sql
${file}
ERROR_QUIET OUTPUT_FILE ${tmpfile})
EXECUTE_PROCESS(
COMMAND sed -e "/^# /d"
-e "/^[ ]*$/d"
-e "/^#pragma GCC set_debug_pwd/d"
-e "/^#ident/d"
RESULT_VARIABLE result OUTPUT_FILE ${abi_check_out} INPUT_FILE ${tmpfile})
IF(NOT ${result} EQUAL 0)
MESSAGE(FATAL_ERROR "sed returned error ${result}")
ENDIF()
FILE(REMOVE ${tmpfile})
EXECUTE_PROCESS(
COMMAND diff -w ${file}.pp ${abi_check_out} RESULT_VARIABLE result)
IF(result MATCHES "No such file or directory")
MESSAGE("Command 'diff' not found. ABI check for ${file} skipped.")
ELSEIF(NOT result EQUAL 0)
IF(ABI_UPDATE)
EXECUTE_PROCESS(COMMAND mv -v ${abi_check_out} ${file}.pp)
ELSE(ABI_UPDATE)
MESSAGE(FATAL_ERROR
"ABI check found difference between ${file}.pp and ${abi_check_out}")
ENDIF(ABI_UPDATE)
ENDIF()
FILE(REMOVE ${abi_check_out})
ENDFOREACH()