Add feed arg to custom_target()

12 files changed, 95 insertions, 19 deletions

diff --git a/docs/markdown/Reference-manual.md b/docs/markdown/Reference-manual.md
index 388c975..16fcbbf 100644
--- a/docs/markdown/Reference-manual.md
+++ b/docs/markdown/Reference-manual.md
@@ -383,6 +383,10 @@ following.
   `{'NAME1': 'value1', 'NAME2': 'value2'}` or `['NAME1=value1', 'NAME2=value2']`,
   or an [`environment()` object](#environment-object) which allows more
   sophisticated environment juggling.
+- `feed` *(since 0.59.0)*: there are some compilers that can't be told to read
+  their input from a file and instead read it from standard input. When this
+  argument is set to true, Meson feeds the input file to `stdin`. Note that
+  your argument list may not contain `@INPUT@` when feed mode is active.
 
 The list of strings passed to the `command` keyword argument accept
 the following special string substitutions:
diff --git a/docs/markdown/snippets/custom-target-feed.md b/docs/markdown/snippets/custom-target-feed.md
new file mode 100644
index 0000000..f965152
--- /dev/null
+++ b/docs/markdown/snippets/custom-target-feed.md
@@ -0,0 +1,4 @@
+## The custom_target() function now accepts a feed argument
+
+It is now possible to provide a `feed: true` argument to `custom_target()` to
+pipe the target's input file to the program's standard input.
diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 21a6c83..aa8e844 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -141,7 +141,7 @@ class SubdirInstallData(InstallDataBase):
 
 class ExecutableSerialisation:
     def __init__(self, cmd_args, env: T.Optional[build.EnvironmentVariables] = None, exe_wrapper=None,
-                 workdir=None, extra_paths=None, capture=None) -> None:
+                 workdir=None, extra_paths=None, capture=None, feed=None) -> None:
         self.cmd_args = cmd_args
         self.env = env
         if exe_wrapper is not None:
@@ -150,6 +150,7 @@ class ExecutableSerialisation:
         self.workdir = workdir
         self.extra_paths = extra_paths
         self.capture = capture
+        self.feed = feed
         self.pickled = False
         self.skip_if_destdir = False
         self.verbose = False
@@ -441,7 +442,7 @@ class Backend:
         return result
 
     def get_executable_serialisation(self, cmd, workdir=None,
-                                     extra_bdeps=None, capture=None,
+                                     extra_bdeps=None, capture=None, feed=None,
                                      env: T.Optional[build.EnvironmentVariables] = None):
         exe = cmd[0]
         cmd_args = cmd[1:]
@@ -489,17 +490,18 @@ class Backend:
         workdir = workdir or self.environment.get_build_dir()
         return ExecutableSerialisation(exe_cmd + cmd_args, env,
                                        exe_wrapper, workdir,
-                                       extra_paths, capture)
+                                       extra_paths, capture, feed)
 
     def as_meson_exe_cmdline(self, tname, exe, cmd_args, workdir=None,
-                             extra_bdeps=None, capture=None, force_serialize=False,
+                             extra_bdeps=None, capture=None, feed=None,
+                             force_serialize=False,
                              env: T.Optional[build.EnvironmentVariables] = None,
                              verbose: bool = False):
         '''
         Serialize an executable for running with a generator or a custom target
         '''
         cmd = [exe] + cmd_args
-        es = self.get_executable_serialisation(cmd, workdir, extra_bdeps, capture, env)
+        es = self.get_executable_serialisation(cmd, workdir, extra_bdeps, capture, feed, env)
         es.verbose = verbose
         reasons = []
         if es.extra_paths:
@@ -521,12 +523,19 @@ class Backend:
 
         if capture:
             reasons.append('to capture output')
+        if feed:
+            reasons.append('to feed input')
 
         if not force_serialize:
-            if not capture:
+            if not capture and not feed:
                 return es.cmd_args, ''
+            args = []
+            if capture:
+                args += ['--capture', capture]
+            if feed:
+                args += ['--feed', feed]
             return ((self.environment.get_build_command() +
-                    ['--internal', 'exe', '--capture', capture, '--'] + es.cmd_args),
+                    ['--internal', 'exe'] + args + ['--'] + es.cmd_args),
                     ', '.join(reasons))
 
         if isinstance(exe, (programs.ExternalProgram,
@@ -538,10 +547,11 @@ class Backend:
             basename = os.path.basename(exe)
 
         # Can't just use exe.name here; it will likely be run more than once
-        # Take a digest of the cmd args, env, workdir, and capture. This avoids
-        # collisions and also makes the name deterministic over regenerations
-        # which avoids a rebuild by Ninja because the cmdline stays the same.
-        data = bytes(str(es.env) + str(es.cmd_args) + str(es.workdir) + str(capture),
+        # Take a digest of the cmd args, env, workdir, capture, and feed. This
+        # avoids collisions and also makes the name deterministic over
+        # regenerations which avoids a rebuild by Ninja because the cmdline
+        # stays the same.
+        data = bytes(str(es.env) + str(es.cmd_args) + str(es.workdir) + str(capture) + str(feed),
                      encoding='utf-8')
         digest = hashlib.sha1(data).hexdigest()
         scratch_file = f'meson_exe_{basename}_{digest}.dat'
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 597789b..d6b535b 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -975,6 +975,7 @@ class NinjaBackend(backends.Backend):
         cmd, reason = self.as_meson_exe_cmdline(target.name, target.command[0], cmd[1:],
                                                 extra_bdeps=target.get_transitive_build_target_deps(),
                                                 capture=ofilenames[0] if target.capture else None,
+                                                feed=srcs[0] if target.feed else None,
                                                 env=target.env)
         if reason:
             cmd_type = f' (wrapped by meson {reason})'
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index 7fcc324..6e6e47f 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -563,6 +563,7 @@ class Vs2010Backend(backends.Backend):
                                                    workdir=tdir_abs,
                                                    extra_bdeps=extra_bdeps,
                                                    capture=ofilenames[0] if target.capture else None,
+                                                   feed=srcs[0] if target.feed else None,
                                                    force_serialize=True,
                                                    env=target.env)
         if target.build_always_stale:
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index f9de5c4..d72aab8 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -2198,6 +2198,7 @@ class CustomTarget(Target, CommandBase):
         'output',
         'command',
         'capture',
+        'feed',
         'install',
         'install_dir',
         'install_mode',
@@ -2296,6 +2297,9 @@ class CustomTarget(Target, CommandBase):
         self.capture = kwargs.get('capture', False)
         if self.capture and len(self.outputs) != 1:
             raise InvalidArguments('Capturing can only output to a single file.')
+        self.feed = kwargs.get('feed', False)
+        if self.feed and len(self.sources) != 1:
+            raise InvalidArguments('Feeding can only input from a single file.')
         self.console = kwargs.get('console', False)
         if not isinstance(self.console, bool):
             raise InvalidArguments('"console" kwarg only accepts booleans')
@@ -2311,10 +2315,11 @@ class CustomTarget(Target, CommandBase):
                 raise InvalidArguments('Depfile must be a plain filename without a subdirectory.')
             self.depfile = depfile
         self.command = self.flatten_command(kwargs['command'])
-        if self.capture:
-            for c in self.command:
-                if isinstance(c, str) and '@OUTPUT@' in c:
-                    raise InvalidArguments('@OUTPUT@ is not allowed when capturing output.')
+        for c in self.command:
+            if self.capture and isinstance(c, str) and '@OUTPUT@' in c:
+                raise InvalidArguments('@OUTPUT@ is not allowed when capturing output.')
+            if self.feed and isinstance(c, str) and '@INPUT@' in c:
+                raise InvalidArguments('@INPUT@ is not allowed when feeding input.')
         if 'install' in kwargs:
             self.install = kwargs['install']
             if not isinstance(self.install, bool):
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 1a9872d..693924f 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -1694,9 +1694,11 @@ external dependencies (including libraries) must go to "dependencies".''')
     @FeatureNewKwargs('custom_target', '0.48.0', ['console'])
     @FeatureNewKwargs('custom_target', '0.47.0', ['install_mode', 'build_always_stale'])
     @FeatureNewKwargs('custom_target', '0.40.0', ['build_by_default'])
+    @FeatureNewKwargs('custom_target', '0.59.0', ['feed'])
     @permittedKwargs({'input', 'output', 'command', 'install', 'install_dir', 'install_mode',
                       'build_always', 'capture', 'depends', 'depend_files', 'depfile',
-                      'build_by_default', 'build_always_stale', 'console', 'env'})
+                      'build_by_default', 'build_always_stale', 'console', 'env',
+                      'feed'})
     def func_custom_target(self, node, args, kwargs):
         if len(args) != 1:
             raise InterpreterException('custom_target: Only one positional argument is allowed, and it must be a string name')
diff --git a/mesonbuild/scripts/meson_exe.py b/mesonbuild/scripts/meson_exe.py
index ea0fef6..9c1ae59 100644
--- a/mesonbuild/scripts/meson_exe.py
+++ b/mesonbuild/scripts/meson_exe.py
@@ -29,6 +29,7 @@ def buildparser() -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(description='Custom executable wrapper for Meson. Do not run on your own, mmm\'kay?')
     parser.add_argument('--unpickle')
     parser.add_argument('--capture')
+    parser.add_argument('--feed')
     return parser
 
 def run_exe(exe: ExecutableSerialisation, extra_env: T.Optional[dict] = None) -> int:
@@ -53,13 +54,17 @@ def run_exe(exe: ExecutableSerialisation, extra_env: T.Optional[dict] = None) ->
                 ['Z:' + p for p in exe.extra_paths] + child_env.get('WINEPATH', '').split(';')
             )
 
+    stdin = None
+    if exe.feed:
+        stdin = open(exe.feed, 'rb')
+
     pipe = subprocess.PIPE
     if exe.verbose:
         assert not exe.capture, 'Cannot capture and print to console at the same time'
         pipe = None
 
     p = subprocess.Popen(cmd_args, env=child_env, cwd=exe.workdir,
-                         close_fds=False, stdout=pipe, stderr=pipe)
+                         close_fds=False, stdin=stdin, stdout=pipe, stderr=pipe)
     stdout, stderr = p.communicate()
 
     if p.returncode == 0xc0000135:
@@ -103,13 +108,13 @@ def run(args: T.List[str]) -> int:
     if not options.unpickle and not cmd_args:
         parser.error('either --unpickle or executable and arguments are required')
     if options.unpickle:
-        if cmd_args or options.capture:
+        if cmd_args or options.capture or options.feed:
             parser.error('no other arguments can be used with --unpickle')
         with open(options.unpickle, 'rb') as f:
             exe = pickle.load(f)
             exe.pickled = True
     else:
-        exe = ExecutableSerialisation(cmd_args, capture=options.capture)
+        exe = ExecutableSerialisation(cmd_args, capture=options.capture, feed=options.feed)
 
     return run_exe(exe)
 
diff --git a/test cases/common/243 custom target feed/data_source.txt b/test cases/common/243 custom target feed/data_source.txt
new file mode 100644
index 0000000..0c23cc0
--- /dev/null
+++ b/test cases/common/243 custom target feed/data_source.txt
@@ -0,0 +1 @@
+This is a text only input file.
diff --git a/test cases/common/243 custom target feed/meson.build b/test cases/common/243 custom target feed/meson.build
new file mode 100644
index 0000000..1cda37d
--- /dev/null
+++ b/test cases/common/243 custom target feed/meson.build
@@ -0,0 +1,24 @@
+project('custom target feed', 'c')
+
+python3 = import('python3').find_python()
+
+# Note that this will not add a dependency to the compiler executable.
+# Code will not be rebuilt if it changes.
+comp = '@0@/@1@'.format(meson.current_source_dir(), 'my_compiler.py')
+
+mytarget = custom_target('bindat',
+  output : 'data.dat',
+  input : 'data_source.txt',
+  feed : true,
+  command : [python3, comp, '@OUTPUT@'],
+  install : true,
+  install_dir : 'subdir'
+)
+
+ct_output_exists = '''import os, sys
+if not os.path.exists(sys.argv[1]):
+  print("could not find {!r} in {!r}".format(sys.argv[1], os.getcwd()))
+  sys.exit(1)
+'''
+
+test('capture-wrote', python3, args : ['-c', ct_output_exists, mytarget])
diff --git a/test cases/common/243 custom target feed/my_compiler.py b/test cases/common/243 custom target feed/my_compiler.py
new file mode 100755
index 0000000..97d4208
--- /dev/null
+++ b/test cases/common/243 custom target feed/my_compiler.py
@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+
+import sys
+
+if __name__ == '__main__':
+    if len(sys.argv) != 2:
+        print(sys.argv[0], 'output_file')
+        sys.exit(1)
+    ifile = sys.stdin.read()
+    if ifile != 'This is a text only input file.\n':
+        print('Malformed input')
+        sys.exit(1)
+    with open(sys.argv[1], 'w+') as f:
+        f.write('This is a binary output file.')
diff --git a/test cases/common/243 custom target feed/test.json b/test cases/common/243 custom target feed/test.json
new file mode 100644
index 0000000..ba66b02
--- /dev/null
+++ b/test cases/common/243 custom target feed/test.json
@@ -0,0 +1,5 @@
+{
+  "installed": [
+    {"type": "file", "file": "usr/subdir/data.dat"}
+  ]
+}