Noissue - Use meson to build the C++ code

meson.build

+project('adblockpluscore', license: ['GPL3'])

[Wladimir Palant, 2017/10/11 10:00:47]

Meson 0.39.1 (what you currently get on Ubuntu) complains: "Not enough arguments
to project(). Needs at least the project name and one language"

I guess that you have a newer version installed, but adding 'cpp' parameter
won't hurt.

[hub, 2017/10/11 18:23:16]

Done.

+
+emcc = find_program('emcc')
+nodejs = find_program('node')

[Wladimir Palant, 2017/10/11 10:00:47]

I tried reading Emscripten configuration and the following worked (note that
meson depends on Python3 so it doesn't introduce an additional dependency):

python = import('python3').find_python()

emscripten_config = get_option('emscripten-config')
command = run_command(python, '-c', 'import os.path,
sys;print(os.path.expanduser(sys.argv[1]))', emscripten_config)
if command.returncode() != 0
  error(command.stderr().strip())
endif
emscripten_config = command.stdout().strip()
message('Emscripten config file: ' + emscripten_config)

command = run_command(python, '-c', 'import
sys;exec(open(sys.argv[1]).read());print(EMSCRIPTEN_ROOT)', emscripten_config)
if command.returncode() != 0
  error(command.stderr().strip())
endif
emcc = join_paths(command.stdout().strip(), 'emcc')
emcc = find_program(emcc)

command = run_command(python, '-c', 'import
sys;exec(open(sys.argv[1]).read());print(NODE_JS)', emscripten_config)
if command.returncode() != 0
  error(command.stderr().strip())
endif
nodejs = find_program(command.stdout().strip(), 'node', 'nodejs')

[hub, 2017/10/11 18:23:17]

Done.

+
+JS_LIBRARY = files('compiled/library.js')
+BINDINGS_GENERATOR = 'bindings.cpp.js'
+BINDINGS_OUTPUT = 'bindings.js'
+COMPILER_OUTPUT = 'compiled.js'
+# params for emcc compilation
+ADDITIONAL_PARAMS = ['-O3', '-m32', '-std=c++1z', '--memory-init-file', '0',
+                     '--emit-symbol-map', '-Wall', '-Werror', '-fno-exceptions',
+                     '-fno-rtti', '--js-library', JS_LIBRARY]
+DEFINES = []
+GENERATION_PARAMS = [
+    ['SHELL_FILE', '"' + meson.source_root() + '/compiled/shell.js"'],
+    ['ASM_JS', '2'],  # "almost asm"
+    ['TOTAL_MEMORY', 16*1024*1024],
+    ['TOTAL_STACK', 1*1024*1024],
+    ['ALLOW_MEMORY_GROWTH', 1],
+    ['NO_EXIT_RUNTIME', 1],
+    ['NO_DYNAMIC_EXECUTION', 1],
+    ['NO_FILESYSTEM', 1],
+    ['INVOKE_RUN', 0],
+    ['TEXTDECODER', 0],
+    ['EXPORTED_RUNTIME_METHODS', '["cwrap", "ccall", "stringToAscii"]']
+]
+
+bindings_sources = files(
+    'compiled/bindings/generator.cpp',
+    'compiled/bindings/main.cpp',
+)
+sources = files(
+    'compiled/bindings/runtime_utils.cpp',
+    'compiled/filter/ActiveFilter.cpp',
+    'compiled/filter/BlockingFilter.cpp',
+    'compiled/filter/CommentFilter.cpp',
+    'compiled/filter/ElemHideBase.cpp',
+    'compiled/filter/ElemHideEmulationFilter.cpp',
+    'compiled/filter/ElemHideException.cpp',
+    'compiled/filter/ElemHideFilter.cpp',
+    'compiled/filter/Filter.cpp',
+    'compiled/filter/InvalidFilter.cpp',
+    'compiled/filter/RegExpFilter.cpp',
+    'compiled/filter/WhitelistFilter.cpp',
+    'compiled/storage/FilterStorage.cpp',
+    'compiled/subscription/DownloadableSubscription.cpp',
+    'compiled/subscription/Subscription.cpp',
+    'compiled/subscription/UserDefinedSubscription.cpp',
+    'compiled/traceInit.cpp'
+)
+
+bindings_generator = custom_target('bindings-generator',
+                   input: bindings_sources + sources,
+                   output: BINDINGS_GENERATOR,
+                   command: [emcc, '-o', '@OUTPUT@',
+                             '-std=c++1z', '--js-library', JS_LIBRARY,
+                             '--js-library',
+                             files('compiled/bindings/library.js'),
+                             '@INPUT@'])
+bindings_output = custom_target('bindings-output',
+                input: bindings_generator,
+                output: BINDINGS_OUTPUT,
+                capture: true,
+                command: [nodejs, '@INPUT@'])
+
+
+defines_args = []
+foreach define : DEFINES
+        defines_args += '-D' + define
+endforeach
+
+generation_args = []
+foreach param : GENERATION_PARAMS
+        generation_args += '-s'
+        generation_args += param[0] + '=' + '@0@'.format(param[1])

[Wladimir Palant, 2017/10/11 10:00:47]

Nit: You should really unify leading whitespace in this file, we should use two
spaces for indentation.

[hub, 2017/10/11 18:23:16]

Done.

+endforeach
+
+optional_args = []
+debug = get_option('buildtype')
+if debug.startswith('debug')
+  optional_args += '-g3'
+endif
+tracing = get_option('tracing')
+if tracing
+  optional_args += '--tracing'
+endif
+
+output_file = meson.source_root() + '/lib/' + COMPILER_OUTPUT
+compiler_output = custom_target('compiled.js',
+                build_by_default: true,
+                input: sources,
+                output: COMPILER_OUTPUT,

[Wladimir Palant, 2017/10/11 10:00:47]

I'd consider that a temporary hack. It's probably best to have compiled.js
generated in the build/ directory and adjust require() paths accordingly.

[hub, 2017/10/11 18:23:17]

Acknowledged.

+                command: [emcc, '-o', output_file, '-std=c++1z',

[Wladimir Palant, 2017/10/11 10:00:47]

-std=c++1z parameter is unnecessary here, it is already part of
ADDITIONAL_PARAMS.

[hub, 2017/10/11 18:23:16]

Done.

+                '--post-js', bindings_output, '@INPUT@'] +
+                defines_args + generation_args + optional_args +
+                ADDITIONAL_PARAMS)

[Wladimir Palant, 2017/10/11 10:00:47]

Object files should really be generated as separate targets, to make the builds
faster. If I make sources a list of strings rather than files, the following
works for me:

compiler_args = defines_args + generation_args + optional_args +
ADDITIONAL_PARAMS

objects = []
foreach source_file : sources
  output_file = source_file + '.o'
  objects += custom_target(output_file,
                           input: files(source_file),
                           output: source_file.underscorify() + '.o',
                           command: [emcc, '-c', '-o', '@OUTPUT@', '@INPUT@'] +
                                    compiler_args)
endforeach

output_file = meson.source_root() + '/lib/' + COMPILER_OUTPUT
compiler_output = custom_target('compiled.js',
                build_by_default: true,
                input: objects,
                output: COMPILER_OUTPUT,
                command: [emcc, '-o', output_file, '--post-js', bindings_output,
                          '@INPUT@'] + compiler_args)

[hub, 2017/10/11 18:23:16]

I wanted to use the c++ targets, but meson doesn't allow overriding the compiler
- expect by passing environment, which we don't want to have too. It is a
feature according to them.

Your suggestion make sense.

[Wladimir Palant, 2017/10/11 21:01:23]

That's too bad. It would have been much nicer if we could tell to use emcc like
the regular clang.