Implement capture for generators

docs/markdown/Reference-manual.md

@@ -554,6 +554,9 @@ following:
 - `output` a template string (or list of template strings) defining
   how an output file name is (or multiple output names are) generated
   from a single source file name
+- `capture` when this argument is set to true, Meson captures `stdout`
+  of the `executable` and writes it to the target file specified as
+  `output`. Available since v0.43.0.
 
 The returned object also has methods that are documented in the
 [object methods section](#generator-object) below.

docs/markdown/Release-notes-for-0.43.0/001-generator-capture.md

@@ -0,0 +1,4 @@
+## Generator learned capture
+
+Generators can now be configured to capture the standard output. See
+`test cases/common/98 gen extra/meson.build` for an example.

mesonbuild/backend/ninjabackend.py

@@ -1814,6 +1814,19 @@ rule FORTRAN_DEP_HACK
             relout = self.get_target_private_dir(target)
             args = self.replace_paths(target, args)
             cmdlist = exe_arr + self.replace_extra_args(args, genlist)
+            if generator.capture:
+                exe_data = self.serialize_executable(
+                    cmdlist[0],
+                    cmdlist[1:],
+                    self.environment.get_build_dir(),
+                    capture=outfiles[0]
+                )
+                cmd = self.environment.get_build_command() + ['--internal', 'exe', exe_data]
+                abs_pdir = os.path.join(self.environment.get_build_dir(), self.get_target_dir(target))
+                os.makedirs(abs_pdir, exist_ok=True)
+            else:
+                cmd = cmdlist
+
             elem = NinjaBuildElement(self.all_outputs, outfiles, rulename, infilename)
             if generator.depfile is not None:
                 elem.add_item('DEPFILE', depfile)
@@ -1822,7 +1835,7 @@ rule FORTRAN_DEP_HACK
             elem.add_item('DESC', 'Generating {!r}.'.format(sole_output))
             if isinstance(exe, build.BuildTarget):
                 elem.add_dep(self.get_target_filename(exe))
-            elem.add_item('COMMAND', cmdlist)
+            elem.add_item('COMMAND', cmd)
             elem.write(outfile)
 
     def scan_fortran_module_outputs(self, target):

mesonbuild/backend/vs2010backend.py

@@ -128,6 +128,16 @@ class Vs2010Backend(backends.Backend):
                              .replace("@BUILD_ROOT@", self.environment.get_build_dir())
                             for x in args]
                     cmd = exe_arr + self.replace_extra_args(args, genlist)
+                    if generator.capture:
+                        exe_data = self.serialize_executable(
+                            cmd[0],
+                            cmd[1:],
+                            self.environment.get_build_dir(),
+                            capture=outfiles[0]
+                        )
+                        cmd = self.environment.get_build_command() + ['--internal', 'exe', exe_data]
+                        abs_pdir = os.path.join(self.environment.get_build_dir(), self.get_target_dir(target))
+                        os.makedirs(abs_pdir, exist_ok=True)
                     cbs = ET.SubElement(idgroup, 'CustomBuild', Include=infilename)
                     ET.SubElement(cbs, 'Command').text = ' '.join(self.quote_arguments(cmd))
                     ET.SubElement(cbs, 'Outputs').text = ';'.join(outfiles)

mesonbuild/build.py

@@ -1019,6 +1019,7 @@ class Generator:
             raise InvalidArguments('First generator argument must be an executable.')
         self.exe = exe
         self.depfile = None
+        self.capture = False
         self.process_kwargs(kwargs)
 
     def __repr__(self):
@@ -1062,6 +1063,11 @@ class Generator:
             if os.path.split(depfile)[1] != depfile:
                 raise InvalidArguments('Depfile must be a plain filename without a subdirectory.')
             self.depfile = depfile
+        if 'capture' in kwargs:
+            capture = kwargs['capture']
+            if not isinstance(capture, bool):
+                raise InvalidArguments('Capture must be boolean.')
+            self.capture = capture
 
     def get_base_outnames(self, inname):
         plainname = os.path.split(inname)[1]

mesonbuild/interpreter.py

@@ -1335,7 +1335,7 @@ permitted_kwargs = {'add_global_arguments': {'language'},
                     'declare_dependency': {'include_directories', 'link_with', 'sources', 'dependencies', 'compile_args', 'link_args', 'version'},
                     'executable': exe_kwargs,
                     'find_program': {'required', 'native'},
-                    'generator': {'arguments', 'output', 'depfile'},
+                    'generator': {'arguments', 'output', 'depfile', 'capture'},
                     'include_directories': {'is_system'},
                     'install_data': {'install_dir', 'install_mode', 'sources'},
                     'install_headers': {'install_dir', 'subdir'},

test cases/common/98 gen extra/meson.build

@@ -28,3 +28,13 @@ plainname_gen = generator(prog2,
 plainname_src = plainname_gen.process('name.l')
 
 test('plainname', executable('plainname', plainname_src))
+
+prog3 = find_program('srcgen3.py')
+capture_gen = generator(prog3,
+  output : ['@BASENAME@.yy.c'],
+  arguments : ['@INPUT@'],
+  capture : true)
+
+capture_src = capture_gen.process('name.l')
+
+test('capture', executable('capture', capture_src))

test cases/common/98 gen extra/srcgen3.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+import argparse
+
+parser = argparse.ArgumentParser()
+parser.add_argument('input',
+                    help='the input file')
+
+options = parser.parse_args(sys.argv[1:])
+
+with open(options.input) as f:
+    content = f.read().strip()
+
+print(content)