cmake: Add support for add_custom_target() with a command

The command could have no output, in which case we create a dummy one.

mesonbuild/cmake/data/run_ctgt.py

@@ -13,13 +13,16 @@ SEPARATOR = ';;;'
 parser = argparse.ArgumentParser(description='Wrapper for add_custom_command')
 parser.add_argument('-d', '--directory', type=str, metavar='D', required=True, help='Working directory to cwd to')
 parser.add_argument('-o', '--outputs', nargs='+', metavar='O', required=True, help='Expected output files')
-parser.add_argument('-O', '--original-outputs', nargs='+', metavar='O', required=True, help='Output files expected by CMake')
-parser.add_argument('commands', nargs=argparse.REMAINDER, help='A "{}" separated list of commands'.format(SEPARATOR))
+parser.add_argument('-O', '--original-outputs', nargs='*', metavar='O', default=[], help='Output files expected by CMake')
+parser.add_argument('commands', nargs=argparse.REMAINDER, help='A "{}" seperated list of commands'.format(SEPERATOR))
 
 # Parse
 args = parser.parse_args()
 
-if len(args.outputs) != len(args.original_outputs):
+dummy_target = None
+if len(args.outputs) == 1 and len(args.original_outputs) == 0:
+    dummy_target = args.outputs[0]
+elif len(args.outputs) != len(args.original_outputs):
     print('Length of output list and original output list differ')
     sys.exit(1)
 
@@ -39,6 +42,11 @@ for i in commands:
 
     subprocess.run(i, cwd=args.directory)
 
+if dummy_target:
+    with open(dummy_target, 'a'):
+        os.utime(dummy_target, None)
+    exit(0)
+
 # Copy outputs
 zipped_outputs = zip(args.outputs, args.original_outputs)
 for expected, generated in zipped_outputs:

mesonbuild/cmake/interpreter.py

@@ -408,7 +408,10 @@ class ConverterCustomTarget:
     out_counter = 0  # type: int
 
     def __init__(self, target: CMakeGeneratorTarget):
+        self.name = target.name
+        if not self.name:
             self.name = 'custom_tgt_{}'.format(ConverterCustomTarget.tgt_counter)
+            ConverterCustomTarget.tgt_counter += 1
         self.original_outputs = list(target.outputs)
         self.outputs = [os.path.basename(x) for x in self.original_outputs]
         self.conflict_map = {}
@@ -418,8 +421,6 @@ class ConverterCustomTarget:
         self.inputs = []
         self.depends = []
 
-        ConverterCustomTarget.tgt_counter += 1
-
     def __repr__(self) -> str:
         return '<{}: {}>'.format(self.__class__.__name__, self.outputs)
 
@@ -729,6 +730,7 @@ class CMakeInterpreter:
             for j in i.artifacts:
                 output_target_map[os.path.basename(j)] = i
         for i in self.custom_targets:
+            output_target_map[_target_key(i.name)] = i
             for j in i.original_outputs:
                 output_target_map[_generated_file_key(j)] = i
         object_libs = []
@@ -971,6 +973,11 @@ class CMakeInterpreter:
 
             tgt_var = tgt.name  # type: str
 
+            # If the custom target does not declare any output, create a dummy
+            # one that can be used as dependency.
+            if not tgt.outputs:
+                tgt.outputs = [tgt.name + '.h']
+
             def resolve_source(x: Any) -> Any:
                 if isinstance(x, ConverterTarget):
                     if x.name not in processed:
@@ -991,6 +998,7 @@ class CMakeInterpreter:
             command = []
             command += [id_node(run_script_var)]
             command += ['-o', '@OUTPUT@']
+            if tgt.original_outputs:
                 command += ['-O'] + tgt.original_outputs
             command += ['-d', tgt.working_dir]
 

mesonbuild/cmake/traceparser.py

@@ -52,12 +52,12 @@ class CMakeTarget:
             propSTR += "      '{}': {}\n".format(i, self.properties[i])
         return s.format(self.name, self.type, self.imported, propSTR, self.tline)
 
-class CMakeGeneratorTarget:
-    def __init__(self):
+class CMakeGeneratorTarget(CMakeTarget):
+    def __init__(self, name):
+        super().__init__(name, 'CUSTOM', {})
         self.outputs = []        # type: List[str]
         self.command = []        # type: List[List[str]]
         self.working_dir = None  # type: Optional[str]
-        self.depends = []        # type: List[str]
 
 class CMakeTraceParser:
     def __init__(self, permissive: bool = False):
@@ -237,7 +237,7 @@ class CMakeTraceParser:
         else:
             self.targets[args[0]] = CMakeTarget(args[0], 'NORMAL', {}, tline=tline)
 
-    def _cmake_add_custom_command(self, tline: CMakeTraceLine):
+    def _cmake_add_custom_command(self, tline: CMakeTraceLine, name=None):
         # DOC: https://cmake.org/cmake/help/latest/command/add_custom_command.html
         args = list(tline.args) # Make a working copy
 
@@ -252,7 +252,7 @@ class CMakeTraceParser:
                       'IMPLICIT_DEPENDS', 'WORKING_DIRECTORY', 'COMMENT', 'DEPFILE',
                       'JOB_POOL', 'VERBATIM', 'APPEND', 'USES_TERMINAL', 'COMMAND_EXPAND_LISTS']
 
-        target = CMakeGeneratorTarget()
+        target = CMakeGeneratorTarget(name)
 
         def handle_output(key: str, target: CMakeGeneratorTarget) -> None:
             target.outputs += [key]
@@ -297,6 +297,8 @@ class CMakeTraceParser:
         target.command = [self._guess_files(x) for x in target.command]
 
         self.custom_targets += [target]
+        if name:
+            self.targets[name] = target
 
     def _cmake_add_custom_target(self, tline: CMakeTraceLine):
         # DOC: https://cmake.org/cmake/help/latest/command/add_custom_target.html
@@ -304,7 +306,8 @@ class CMakeTraceParser:
         if len(tline.args) < 1:
             return self._gen_exception('add_custom_target', 'requires at least one argument', tline)
 
-        self.targets[tline.args[0]] = CMakeTarget(tline.args[0], 'CUSTOM', {}, tline=tline)
+        # It's pretty much the same as a custom command
+        self._cmake_add_custom_command(tline, tline.args[0])
 
     def _cmake_set_property(self, tline: CMakeTraceLine) -> None:
         # DOC: https://cmake.org/cmake/help/latest/command/set_property.html