add support for cmakedefine in configure_file()

The added format argument for configure_file allows to specify the kind of
file that is treated. It defaults to 'meson', but can also have the 'cmake'
or 'cmake@' value to treat config.h.in files in the cmake format with #cmakedefine
statements.

docs/markdown/Reference-manual.md

@@ -186,7 +186,12 @@ These are all the supported keyword arguments:
   `output`. Available since v0.41.0.
 - `command` as explained above, if specified, Meson does not create
   the file itself but rather runs the specified command, which allows
-  you to do fully custom file generation
+  you to do fully custom file generation.
+- `format` *(added 0.46.0)* the format of defines. It defaults to `meson`, and so substitutes
+`#mesondefine` statements and variables surrounded by `@` characters, you can also use `cmake`
+to replace `#cmakedefine` statements and variables with the `${variable}` syntax. Finally you can use
+`cmake@` in which case substitutions will apply on `#cmakedefine` statements and variables with
+the `@variable@` syntax.
 - `input` the input file name. If it's not specified in configuration
   mode, all the variables in the `configuration:` object (see above)
   are written to the `output:` file.

mesonbuild/interpreter.py

@@ -1463,7 +1463,7 @@ permitted_kwargs = {'add_global_arguments': {'language'},
                     'add_test_setup': {'exe_wrapper', 'gdb', 'timeout_multiplier', 'env'},
                     'benchmark': {'args', 'env', 'should_fail', 'timeout', 'workdir', 'suite'},
                     'build_target': known_build_target_kwargs,
-                    'configure_file': {'input', 'output', 'configuration', 'command', 'install_dir', 'capture', 'install'},
+                    'configure_file': {'input', 'output', 'configuration', 'command', 'install_dir', 'capture', 'install', 'format'},
                     'custom_target': {'input', 'output', 'command', 'install', 'install_dir', 'build_always', 'capture', 'depends', 'depend_files', 'depfile', 'build_by_default'},
                     'dependency': {'default_options', 'fallback', 'language', 'main', 'method', 'modules', 'optional_modules', 'native', 'required', 'static', 'version'},
                     'declare_dependency': {'include_directories', 'link_with', 'sources', 'dependencies', 'compile_args', 'link_args', 'link_whole', 'version'},
@@ -2885,6 +2885,16 @@ root and issuing %s.
             if 'command' not in kwargs:
                 raise InterpreterException('"capture" keyword requires "command" keyword.')
 
+        if 'format' in kwargs:
+            format = kwargs['format']
+            if not isinstance(format, str):
+                raise InterpreterException('"format" keyword must be a string.')
+        else:
+            format = 'meson'
+
+        if format not in ('meson', 'cmake', 'cmake@'):
+            raise InterpreterException('"format" possible values are "meson", "cmake" or "cmake@".')
+
         # Validate input
         inputfile = None
         ifile_abs = None
@@ -2924,7 +2934,7 @@ root and issuing %s.
             if inputfile is not None:
                 os.makedirs(os.path.join(self.environment.build_dir, self.subdir), exist_ok=True)
                 missing_variables = mesonlib.do_conf_file(ifile_abs, ofile_abs,
-                                                          conf.held_object)
+                                                          conf.held_object, format)
                 if missing_variables:
                     var_list = ", ".join(map(repr, sorted(missing_variables)))
                     mlog.warning(

mesonbuild/mesonlib.py

@@ -541,8 +541,13 @@ def has_path_sep(name, sep='/\\'):
             return True
     return False
 
-def do_replacement(regex, line, confdata):
+def do_replacement(regex, line, format, confdata):
     missing_variables = set()
+    start_tag = '@'
+    backslash_tag = '\\@'
+    if format == 'cmake':
+        start_tag = '${'
+        backslash_tag = '\\${'
 
     def variable_replace(match):
         # Pairs of escape characters before '@' or '\@'
@@ -550,8 +555,8 @@ def do_replacement(regex, line, confdata):
             num_escapes = match.end(0) - match.start(0)
             return '\\' * (num_escapes // 2)
         # Single escape character and '@'
-        elif match.group(0) == '\\@':
-            return '@'
+        elif match.group(0) == backslash_tag:
+            return start_tag
         # Template variable to be replaced
         else:
             varname = match.group(1)
@@ -591,7 +596,7 @@ def do_mesondefine(line, confdata):
         raise MesonException('#mesondefine argument "%s" is of unknown type.' % varname)
 
 
-def do_conf_file(src, dst, confdata):
+def do_conf_file(src, dst, confdata, format):
     try:
         with open(src, encoding='utf-8') as f:
             data = f.readlines()
@@ -599,14 +604,24 @@ def do_conf_file(src, dst, confdata):
         raise MesonException('Could not read input file %s: %s' % (src, str(e)))
     # Only allow (a-z, A-Z, 0-9, _, -) as valid characters for a define
     # Also allow escaping '@' with '\@'
-    regex = re.compile(r'(?:\\\\)+(?=\\?@)|\\@|@([-a-zA-Z0-9_]+)@')
+    if format in ['meson', 'cmake@']:
+        regex = re.compile(r'(?:\\\\)+(?=\\?@)|\\@|@([-a-zA-Z0-9_]+)@')
+    elif format == 'cmake':
+        regex = re.compile(r'(?:\\\\)+(?=\\?\$)|\\\${|\${([-a-zA-Z0-9_]+)}')
+    else:
+        raise MesonException('Format "{}" not handled'.format(format))
+
+    search_token = '#mesondefine'
+    if format != 'meson':
+        search_token = '#cmakedefine'
+
     result = []
     missing_variables = set()
     for line in data:
-        if line.startswith('#mesondefine'):
+        if line.startswith(search_token):
             line = do_mesondefine(line, confdata)
         else:
-            line, missing = do_replacement(regex, line, confdata)
+            line, missing = do_replacement(regex, line, format, confdata)
             missing_variables.update(missing)
         result.append(line)
     dst_tmp = dst + '~'

test cases/common/16 configure file/config7.h.in

@@ -0,0 +1,16 @@
+/* No escape */
+#define MESSAGE1 "${var1}"
+
+/* Single escape means no replace */
+#define MESSAGE2 "\${var1}"
+
+/* Replace pairs of escapes before '@' or '\@' with escape characters
+ * (note we have to double number of pairs due to C string escaping)
+ */
+#define MESSAGE3 "\\\\${var1}"
+
+/* Pairs of escapes and then single escape to avoid replace */
+#define MESSAGE4 "\\\\\${var1}"
+
+/* Check escape character outside variables */
+#define MESSAGE5 "\\ ${ \${ \\\\${ \\\\\${"

test cases/common/16 configure file/meson.build

@@ -137,3 +137,15 @@ cfile = configure_file(input : 'config.h.in',
   output : 'do_not_get_installed.h',
   install_dir : '',
   configuration : conf)
+
+# Test escaping with cmake format
+conf7 = configuration_data()
+conf7.set('var1', 'foo')
+conf7.set('var2', 'bar')
+configure_file(
+  input : 'config7.h.in',
+  output : '@BASENAME@',
+  format : 'cmake',
+  configuration : conf7
+)
+test('test7', executable('prog7', 'prog7.c'))

test cases/common/16 configure file/prog7.c

@@ -0,0 +1,10 @@
+#include <string.h>
+#include <config7.h>
+
+int main(int argc, char **argv) {
+    return strcmp(MESSAGE1, "foo")
+        || strcmp(MESSAGE2, "${var1}")
+        || strcmp(MESSAGE3, "\\foo")
+        || strcmp(MESSAGE4, "\\${var1}")
+        || strcmp(MESSAGE5, "\\ ${ ${ \\${ \\${");
+}