Add build_args() that can be passed as extra_args to build targets

The principal use-case is to pass different compiler flags to library()
depending if it's building the static or shared library.

Closes: mesonbuild#3304

mesonbuild/build.py

@@ -62,6 +62,7 @@
                       'native': True,
                       'build_by_default': True,
                       'override_options': True,
+                      'extra_args': True,
                       }
 
 # These contain kwargs supported by both static and shared libraries. These are
@@ -667,9 +668,9 @@ def process_kwargs(self, kwargs, environment):
         for linktarget in lwhole:
             self.link_whole(linktarget)
 
-        c_pchlist, cpp_pchlist, clist, cpplist, cslist, valalist,  objclist, objcpplist, fortranlist, rustlist \
+        c_pchlist, cpp_pchlist, clist, cpplist, cslist, valalist,  objclist, objcpplist, fortranlist, rustlist, extra_args \
             = extract_as_list(kwargs, 'c_pch', 'cpp_pch', 'c_args', 'cpp_args', 'cs_args', 'vala_args', 'objc_args',
-                              'objcpp_args', 'fortran_args', 'rust_args')
+                              'objcpp_args', 'fortran_args', 'rust_args', 'extra_args')
 
         self.add_pch('c', c_pchlist)
         self.add_pch('cpp', cpp_pchlist)
@@ -679,6 +680,15 @@ def process_kwargs(self, kwargs, environment):
         for key, value in compiler_args.items():
             self.add_compiler_args(key, value)
 
+        for obj in extra_args:
+            obj = obj.held_object
+            if not isinstance(obj, BuildArgs):
+                raise InvalidArguments('extra_args must be a list of build_args objects.')
+            for target_type in self.target_types:
+                compiler_args = obj.compiler_args.get(target_type, {})
+                for key, value in compiler_args.items():
+                    self.add_compiler_args(key, value)
+
         if not isinstance(self, Executable):
             self.vala_header = kwargs.get('vala_header', self.name + '.h')
             self.vala_vapi = kwargs.get('vala_vapi', self.name + '.vapi')
@@ -1174,6 +1184,8 @@ def get_extra_args(self):
         return self.extra_args
 
 class Executable(BuildTarget):
+    target_types = ['executable']
+
     def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
         super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs)
         # Unless overridden, executables have no suffix or prefix. Except on
@@ -1249,6 +1261,8 @@ def is_linkable_target(self):
         return self.is_linkwithable
 
 class StaticLibrary(BuildTarget):
+    target_types = ['library', 'static_library']
+
     def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
         if 'pic' not in kwargs and 'b_staticpic' in environment.coredata.base_options:
             kwargs['pic'] = environment.coredata.base_options['b_staticpic'].value
@@ -1303,6 +1317,8 @@ def is_linkable_target(self):
         return True
 
 class SharedLibrary(BuildTarget):
+    target_types = ['library', 'shared_library']
+
     def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
         self.soversion = None
         self.ltversion = None
@@ -1804,6 +1820,8 @@ def type_suffix(self):
         return "@run"
 
 class Jar(BuildTarget):
+    target_type = ['jar']
+
     def __init__(self, name, subdir, subproject, is_cross, sources, objects, environment, kwargs):
         super().__init__(name, subdir, subproject, is_cross, sources, objects, environment, kwargs)
         for s in self.sources:
@@ -1927,6 +1945,20 @@ def __init__(self, *, exe_wrapper=None, gdb=None, timeout_multiplier=None, env=N
         self.timeout_multiplier = timeout_multiplier
         self.env = env
 
+class BuildArgs:
+    def __init__(self):
+        self.compiler_args = {}
+
+    def __repr__(self):
+        return repr(self.compiler_args)
+
+    def add_compiler_args(self, compiler_args, target_type, language):
+        if target_type not in self.compiler_args:
+            self.compiler_args[target_type] = {}
+        if language not in self.compiler_args[target_type]:
+            self.compiler_args[target_type][language] = []
+        self.compiler_args[target_type][language] += compiler_args
+
 def get_sources_string_names(sources):
     '''
     For the specified list of @sources which can be strings, Files, or targets,

mesonbuild/interpreter.py

@@ -1206,6 +1206,41 @@ def first_supported_argument_method(self, args, kwargs):
         mlog.log('First supported argument:', mlog.red('None'))
         return []
 
+class BuildArgsHolder(MutableInterpreterObject, ObjectHolder):
+    def __init__(self):
+        InterpreterObject.__init__(self)
+        ObjectHolder.__init__(self, build.BuildArgs())
+        self.used = False # These objects become immutable after use.
+        self.methods.update({'add_compiler_args': self.add_compiler_args,
+                             })
+
+    def is_used(self):
+        return self.used
+
+    def mark_used(self):
+        self.used = True
+
+    @permittedMethodKwargs({'target_type', 'language'})
+    def add_compiler_args(self, args, kwargs):
+        if self.used:
+            raise InterpreterException("Can not set values on build_args object that has been used.")
+
+        check_stringlist(args)
+
+        if 'target_type' not in kwargs:
+            raise InterpreterException('Missing target_type keyword argument')
+        target_type = kwargs['target_type']
+        if not isinstance(target_type, str):
+            raise InterpreterException('target_type keyword argument must be a string')
+
+        if 'language' not in kwargs:
+            raise InterpreterException('Missing language keyword argument')
+        language = kwargs['language']
+        if not isinstance(language, str):
+            raise InterpreterException('language keyword argument must be a string')
+
+        self.held_object.add_compiler_args(args, target_type, language)
+
 ModuleState = namedtuple('ModuleState', [
     'build_to_src', 'subproject', 'subdir', 'current_lineno', 'environment',
     'project_name', 'project_version', 'backend', 'compilers', 'targets',
@@ -1444,6 +1479,7 @@ def get_cross_property_method(self, args, kwargs):
     'build_by_default',
     'build_rpath',
     'dependencies',
+    'extra_args',
     'extra_files',
     'gui_app',
     'link_with',
@@ -1575,6 +1611,7 @@ def build_func_dict(self):
                            'assert': self.func_assert,
                            'benchmark': self.func_benchmark,
                            'build_target': self.func_build_target,
+                           'build_args': self.func_build_args,
                            'configuration_data': self.func_configuration_data,
                            'configure_file': self.func_configure_file,
                            'custom_target': self.func_custom_target,
@@ -2573,6 +2610,11 @@ def func_build_target(self, node, args, kwargs):
         else:
             raise InterpreterException('Unknown target_type.')
 
+    @noKwargs
+    @noPosargs
+    def func_build_args(self, node, args, kwargs):
+        return BuildArgsHolder()
+
     @permittedKwargs(permitted_kwargs['vcs_tag'])
     def func_vcs_tag(self, node, args, kwargs):
         if 'input' not in kwargs or 'output' not in kwargs:
@@ -3234,6 +3276,11 @@ def build_target(self, node, args, kwargs, targetholder):
         if 'extra_files' in kwargs:
             ef = extract_as_list(kwargs, 'extra_files')
             kwargs['extra_files'] = self.source_strings_to_files(ef)
+        extra_args = extract_as_list(kwargs, 'extra_args')
+        for item in extra_args:
+            if not isinstance(item, BuildArgsHolder):
+                raise InterpreterException('Argument "extra_args" is not a list of build_args')
+            item.mark_used()
         self.check_sources_exist(os.path.join(self.source_root, self.subdir), sources)
         if targetholder is ExecutableHolder:
             targetclass = build.Executable