build: replace kwargs in CustomTarget initializer

Because we don't want to pass the Interpreter kwargs into the build
layer. This turned out to be a mega commit, as there's really on elegant
way to make this change in an incremental way. On the nice side, mypy
made this change super easy, as nearly all of the calls to
`CustomTarget` are fully type checked!

It also turns out that we're not handling install_tags in custom_target
correctly, since we're not converting the boolean values into Optional
values!

1 files changed, 92 insertions, 33 deletions

diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index bed9278..7681834 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -50,7 +50,9 @@ from .interpreterobjects import (
     NullSubprojectInterpreter,
 )
 from .type_checking import (
-    COMMAND_KW, CT_BUILD_ALWAYS, CT_BUILD_ALWAYS_STALE,
+    COMMAND_KW,
+    CT_BUILD_ALWAYS,
+    CT_BUILD_ALWAYS_STALE,
     CT_BUILD_BY_DEFAULT,
     CT_INPUT_KW,
     CT_INSTALL_DIR_KW,
@@ -1696,8 +1698,14 @@ external dependencies (including libraries) must go to "dependencies".''')
             else:
                 vcs_cmd = [' '] # executing this cmd will fail in vcstagger.py and force to use the fallback string
         # vcstagger.py parameters: infile, outfile, fallback, source_dir, replace_string, regex_selector, command...
-        cmd_kwargs = {
-            'command': self.environment.get_build_command() + \
+
+        self._validate_custom_target_outputs(len(kwargs['input']) > 1, kwargs['output'], "vcs_tag")
+
+        tg = build.CustomTarget(
+            kwargs['output'][0],
+            self.subdir,
+            self.subproject,
+            self.environment.get_build_command() + \
                 ['--internal',
                 'vcstagger',
                 '@INPUT0@',
@@ -1706,12 +1714,13 @@ external dependencies (including libraries) must go to "dependencies".''')
                 source_dir,
                 replace_string,
                 regex_selector] + vcs_cmd,
-            'input': kwargs['input'],
-            'output': kwargs['output'],
-            'build_by_default': True,
-            'build_always_stale':True,
-        }
-        return self._func_custom_target_impl(node, [kwargs['output']], cmd_kwargs)
+            self.source_strings_to_files(kwargs['input']),
+            kwargs['output'],
+            build_by_default=True,
+            build_always_stale=True,
+        )
+        self.add_target(tg.name, tg)
+        return tg
 
     @FeatureNew('subdir_done', '0.46.0')
     @noPosargs
@@ -1719,6 +1728,18 @@ external dependencies (including libraries) must go to "dependencies".''')
     def func_subdir_done(self, node, args, kwargs):
         raise SubdirDoneRequest()
 
+    @staticmethod
+    def _validate_custom_target_outputs(has_multi_in: bool, outputs: T.Iterable[str], name: str) -> None:
+        """Checks for additional invalid values in a custom_target output.
+
+        This cannot be done with typed_kwargs because it requires the number of
+        inputs.
+        """
+        for out in outputs:
+            if has_multi_in and ('@PLAINNAME@' in out or '@BASENAME@' in out):
+                raise InvalidArguments(f'{name}: output cannot containe "@PLAINNAME@" or "@BASENAME@" '
+                                       'when there is more than one input (we can\'t know which to use)')
+
     @typed_pos_args('custom_target', optargs=[str])
     @typed_kwargs(
         'custom_target',
@@ -1747,49 +1768,87 @@ external dependencies (including libraries) must go to "dependencies".''')
             FeatureNew.single_use('substitutions in custom_target depfile', '0.47.0', self.subproject, location=node)
 
         # Don't mutate the kwargs
-        kwargs = kwargs.copy()
 
+        build_by_default = kwargs['build_by_default']
+        build_always_stale = kwargs['build_always_stale']
         # Remap build_always to build_by_default and build_always_stale
         if kwargs['build_always'] is not None and kwargs['build_always_stale'] is not None:
             raise InterpreterException('CustomTarget: "build_always" and "build_always_stale" are mutually exclusive')
 
-        if kwargs['build_by_default'] is None and kwargs['install']:
-            kwargs['build_by_default'] = True
+        if build_by_default is None and kwargs['install']:
+            build_by_default = True
 
         elif kwargs['build_always'] is not None:
-            if kwargs['build_by_default'] is None:
-                kwargs['build_by_default'] = kwargs['build_always']
-            kwargs['build_always_stale'] = kwargs['build_by_default']
-
-            # Set this to None to satisfy process_kwargs
-            kwargs['build_always'] = None
+            if build_by_default is None:
+                build_by_default = kwargs['build_always']
+            build_always_stale = kwargs['build_by_default']
 
         # These are are nullaable so that we can know whether they're explicitly
         # set or not. If they haven't been overwritten, set them to their true
         # default
-        if kwargs['build_by_default'] is None:
-            kwargs['build_by_default'] = False
-        if kwargs['build_always_stale'] is None:
-            kwargs['build_always_stale'] = False
+        if build_by_default is None:
+            build_by_default = False
+        if build_always_stale is None:
+            build_always_stale = False
 
-        return self._func_custom_target_impl(node, args, kwargs)
-
-    def _func_custom_target_impl(self, node, args, kwargs):
-        'Implementation-only, without FeatureNew checks, for internal use'
         name = args[0]
         if name is None:
             # name will default to first output, but we cannot do that yet because
             # they could need substitutions (e.g. @BASENAME@) first. CustomTarget()
             # will take care of setting a proper default but name must be an empty
             # string in the meantime.
-            FeatureNew('custom_target() with no name argument', '0.60.0', location=node).use(self.subproject)
+            FeatureNew.single_use('custom_target() with no name argument', '0.60.0', self.subproject, location=node)
             name = ''
-        if 'input' in kwargs:
-            kwargs['input'] = self.source_strings_to_files(extract_as_list(kwargs, 'input'), strict=False)
-        if 'command' in kwargs and isinstance(kwargs['command'], list) and kwargs['command']:
-            if isinstance(kwargs['command'][0], str):
-                kwargs['command'][0] = self.find_program_impl([kwargs['command'][0]])
-        tg = build.CustomTarget(name, self.subdir, self.subproject, kwargs, backend=self.backend)
+        inputs = self.source_strings_to_files(kwargs['input'], strict=False)
+        command = kwargs['command']
+        if command and isinstance(command[0], str):
+            command[0] = self.find_program_impl([command[0]])
+
+        if len(inputs) > 1 and kwargs['feed']:
+            raise InvalidArguments('custom_target: "feed" keyword argument can only be used used with a single input')
+        if len(kwargs['output']) > 1 and kwargs['capture']:
+            raise InvalidArguments('custom_target: "capture" keyword argument can only be used used with a single output')
+        if kwargs['capture'] and kwargs['console']:
+            raise InvalidArguments('custom_target: "capture" and "console" keyword arguments are mutually exclusive')
+        for c in command:
+            if kwargs['capture'] and isinstance(c, str) and '@OUTPUT@' in c:
+                raise InvalidArguments('custom_target: "capture" keyword argument cannot be used with "@OUTPUT@"')
+            if kwargs['feed'] and isinstance(c, str) and '@INPUT@' in c:
+                raise InvalidArguments('custom_target: "feed" keyword argument cannot be used with "@INPUT@"')
+        if kwargs['install'] and not kwargs['install_dir']:
+            raise InvalidArguments('custom_target: "install_dir" keyword argument must be set when "install" is true.')
+        if len(kwargs['install_dir']) > 1:
+            FeatureNew.single_use('multiple install_dir for custom_target', '0.40.0', self.subproject, location=node)
+        if len(kwargs['install_tag']) not in {0, 1, len(kwargs['output'])}:
+            raise InvalidArguments('custom_target: install_tag argument must have 0 or 1 outputs, '
+                                   'or the same number of elements as the output keyword argument. '
+                                   f'(there are {len(kwargs["install_tag"])} install_tags, '
+                                   f'and {len(kwargs["output"])} outputs)')
+
+        self._validate_custom_target_outputs(len(inputs) > 1, kwargs['output'], "custom_target")
+
+        tg = build.CustomTarget(
+            name,
+            self.subdir,
+            self.subproject,
+            command,
+            inputs,
+            kwargs['output'],
+            build_always_stale=build_always_stale,
+            build_by_default=build_by_default,
+            capture=kwargs['capture'],
+            console=kwargs['console'],
+            depend_files=kwargs['depend_files'],
+            depfile=kwargs['depfile'],
+            extra_depends=kwargs['depends'],
+            env=kwargs['env'],
+            feed=kwargs['feed'],
+            install=kwargs['install'],
+            install_dir=kwargs['install_dir'],
+            install_mode=kwargs['install_mode'],
+            install_tag=kwargs['install_tag'],
+            override_options=kwargs['override_options'],
+            backend=self.backend)
         self.add_target(tg.name, tg)
         return tg