Add macro_name option to configure_file

Allow macro_name to be speficied as a parameter to configure_file().
This allows C macro-style include guards to be added to
configure_file()'s output when a template file is not given. This change
simplifies the creation of configure files that define macros with
dynamic names and want the C-style include guards.

docs/markdown/snippets/configure_file_macro_guard.md

@@ -0,0 +1,6 @@
+## [[configure_file]] now has a `macro_name` parameter.
+
+This new paramater, `macro_name` allows C macro-style include guards to be added
+to [[configure_file]]'s output when a template file is not given. This change
+simplifies the creation of configure files that define macros with dynamic names
+and want the C-style include guards.

docs/yaml/functions/configure_file.yaml

@@ -144,3 +144,10 @@ kwargs:
       Set the file encoding for the input and output file.
       The supported encodings are those of python3, see
       [standard-encodings](https://docs.python.org/3/library/codecs.html#standard-encodings).
+
+  macro_name:
+    type: str
+    since: 1.3.0
+    description: |
+      When specified, macro guards will be used instead of '#pragma once'. The
+      macro guard name will be the specified name.

mesonbuild/interpreter/interpreter.py

@@ -2585,6 +2585,7 @@ class Interpreter(InterpreterBase, HoldableObject):
         OUTPUT_KW,
         KwargInfo('output_format', str, default='c', since='0.47.0', since_values={'json': '1.3.0'},
                   validator=in_set_validator({'c', 'json', 'nasm'})),
+        KwargInfo('macro_name', (str, NoneType), default=None, since='1.3.0'),
     )
     def func_configure_file(self, node: mparser.BaseNode, args: T.List[TYPE_var],
                             kwargs: kwtypes.ConfigureFile):
@@ -2676,7 +2677,8 @@ class Interpreter(InterpreterBase, HoldableObject):
                                      'copy a file to the build dir, use the \'copy:\' keyword '
                                      'argument added in 0.47.0', location=node)
             else:
-                mesonlib.dump_conf_header(ofile_abs, conf, output_format)
+                macro_name = kwargs['macro_name']
+                mesonlib.dump_conf_header(ofile_abs, conf, output_format, macro_name)
             conf.used = True
         elif kwargs['command'] is not None:
             if len(inputs) > 1:

mesonbuild/interpreter/kwargs.py

@@ -296,6 +296,7 @@ class ConfigureFile(TypedDict):
     command: T.Optional[T.List[T.Union[build.Executable, ExternalProgram, Compiler, File, str]]]
     input: T.List[FileOrString]
     configuration: T.Optional[T.Union[T.Dict[str, T.Union[str, int, bool]], build.ConfigurationData]]
+    macro_name: T.Optional[str]
 
 
 class Subproject(ExtractRequired):

mesonbuild/utils/universal.py

@@ -1351,7 +1351,7 @@ CONF_C_PRELUDE = '''/*
  * Do not edit, your changes will be lost.
  */
 
-#pragma once
+{}
 
 '''
 
@@ -1360,10 +1360,16 @@ CONF_NASM_PRELUDE = '''; Autogenerated by the Meson build system.
 
 '''
 
-def _dump_c_header(ofile: T.TextIO, cdata: ConfigurationData, output_format: Literal['c', 'nasm']) -> None:
+def _dump_c_header(ofile: T.TextIO,
+                   cdata: ConfigurationData,
+                   output_format: Literal['c', 'nasm'],
+                   macro_name: T.Optional[str]) -> None:
     format_desc: T.Callable[[str], str]
     if output_format == 'c':
-        prelude = CONF_C_PRELUDE
+        if macro_name:
+            prelude = CONF_C_PRELUDE.format('#ifndef {0}\n#define {0}'.format(macro_name))
+        else:
+            prelude = CONF_C_PRELUDE.format('#pragma once')
         prefix = '#'
         format_desc = lambda desc: f'/* {desc} */\n'
     else:  # nasm
@@ -1385,17 +1391,20 @@ def _dump_c_header(ofile: T.TextIO, cdata: ConfigurationData, output_format: Lit
             ofile.write(f'{prefix}define {k} {v}\n\n')
         else:
             raise MesonException('Unknown data type in configuration file entry: ' + k)
+    if output_format == 'c' and macro_name:
+        ofile.write('#endif\n')
 
 
 def dump_conf_header(ofilename: str, cdata: ConfigurationData,
-                     output_format: Literal['c', 'nasm', 'json']) -> None:
+                     output_format: Literal['c', 'nasm', 'json'],
+                     macro_name: T.Optional[str]) -> None:
     ofilename_tmp = ofilename + '~'
     with open(ofilename_tmp, 'w', encoding='utf-8') as ofile:
         if output_format == 'json':
             data = {k: v[0] for k, v in cdata.values.items()}
             json.dump(data, ofile, sort_keys=True)
         else:  # c, nasm
-            _dump_c_header(ofile, cdata, output_format)
+            _dump_c_header(ofile, cdata, output_format, macro_name)
 
     replace_if_different(ofilename, ofilename_tmp)
 

test cases/common/269 configure file output format/expected/config.mg

@@ -0,0 +1,23 @@
+/*
+ * Autogenerated by the Meson build system.
+ * Do not edit, your changes will be lost.
+ */
+
+#ifndef CONFIG_MAGNESIUM_H
+#define CONFIG_MAGNESIUM_H
+
+#define bool
+
+#undef false
+
+/* ultimate question of life, the universe, and everything */
+#define int 42
+
+/* This is
+a multiline
+description */
+#define str "hello world!"
+
+#define unquoted float
+
+#endif

test cases/common/269 configure file output format/meson.build

@@ -27,12 +27,21 @@ config_json = configure_file(
     output: 'config.json'
 )
 
+config_mg = configure_file(
+    configuration: data,
+    macro_name: 'CONFIG_MAGNESIUM_H',
+    output_format: 'c',
+    output: 'config_mg.h'
+)
+
 py = find_program('python3')
 compare_py = files('compare.py')
 expected_config_h = files('expected/config.h')
 expected_config_nasm = files('expected/config.nasm')
 expected_config_json = files('expected/config.json')
+expected_config_mg = files('expected/config.mg')
 
 test('c_output', py, args: [compare_py, expected_config_h, config_h])
 test('nasm_output', py, args: [compare_py, expected_config_nasm, config_nasm])
 test('json_output', py, args: [compare_py, expected_config_json, config_json])
+test('c_mg_output', py, args: [compare_py, expected_config_mg, config_mg])