Permit overriding find_program from the cross file.

docs/markdown/Reference-manual.md

@@ -466,6 +466,12 @@ Keyword arguments are the following:
   then use the `.found()` method on the returned object to check
   whether it was found or not.
 
+- `native` defines how this executable should be searched. By default
+  it is set to `false`, which causes Meson to first look for the
+  executable in the cross file (when cross building) and if it is not
+  defined there, then from the system. If set to `true`, the cross
+  file is ignored and the program is only searched from the system.
+
 Meson will also autodetect scripts with a shebang line and run them
 with the executable/interpreter specified in it both on Windows
 (because the command invocator will reject the command otherwise) and

docs/markdown/snippets/cross_find.md

@@ -0,0 +1,15 @@
+# Can override executables in the cross file
+
+The cross file can now be used for overriding the result of
+`find_program`. As an example if you want to find the `objdump`
+command and have the following definition in your cross file:
+
+    [binaries]
+    ...
+    objdump = '/usr/bin/arm-linux-gnueabihf-objdump-6'
+
+Then issuing the command `find_program('objdump')` will return the
+version specified in the cross file. If you need the build machine's
+objdump, you can specify the `native` keyword like this:
+
+    native_objdump = find_program('objdump', native : true)

mesonbuild/interpreter.py

@@ -1317,7 +1317,7 @@ permitted_kwargs = {'add_global_arguments': {'language'},
                     'custom_target': {'input', 'output', 'command', 'install', 'install_dir', 'build_always', 'capture', 'depends', 'depend_files', 'depfile', 'build_by_default'},
                     'declare_dependency': {'include_directories', 'link_with', 'sources', 'dependencies', 'compile_args', 'link_args', 'version'},
                     'executable': exe_kwargs,
-                    'find_program': {'required'},
+                    'find_program': {'required', 'native'},
                     'generator': {'arguments', 'output', 'depfile'},
                     'include_directories': {'is_system'},
                     'install_data': {'install_dir', 'install_mode', 'sources'},
@@ -1963,13 +1963,22 @@ class Interpreter(InterpreterBase):
                     break
             self.coredata.base_options[optname] = oobj
 
-    @permittedKwargs(permitted_kwargs['find_program'])
-    def func_find_program(self, node, args, kwargs):
-        if not args:
-            raise InterpreterException('No program name specified.')
-        required = kwargs.get('required', True)
-        if not isinstance(required, bool):
-            raise InvalidArguments('"required" argument must be a boolean.')
+    def program_from_cross_file(self, prognames):
+        bins = self.environment.cross_info.config['binaries']
+        for p in prognames:
+            if hasattr(p, 'held_object'):
+                p = p.held_object
+            if isinstance(p, mesonlib.File):
+                continue # Always points to a local (i.e. self generated) file.
+            if not isinstance(p, str):
+                raise InterpreterException('Executable name must be a string.')
+            if p in bins:
+                exename = bins[p]
+                extprog = dependencies.ExternalProgram(exename)
+                progobj = ExternalProgramHolder(extprog)
+                return progobj
+
+    def program_from_system(self, args):
         # Search for scripts relative to current subdir.
         # Do not cache found programs because find_program('foobar')
         # might give different results when run from different source dirs.
@@ -1992,8 +2001,27 @@ class Interpreter(InterpreterBase):
             progobj = ExternalProgramHolder(extprog)
             if progobj.found():
                 return progobj
-        if required and not progobj.found():
+
+    @permittedKwargs(permitted_kwargs['find_program'])
+    def func_find_program(self, node, args, kwargs):
+        if not args:
+            raise InterpreterException('No program name specified.')
+        required = kwargs.get('required', True)
+        if not isinstance(required, bool):
+            raise InvalidArguments('"required" argument must be a boolean.')
+        progobj = None
+        if self.build.environment.is_cross_build():
+            use_native = kwargs.get('native', False)
+            if not isinstance(use_native, bool):
+                raise InvalidArguments('Argument to "native" must be a boolean.')
+            if not use_native:
+                 progobj = self.program_from_cross_file(args)
+        if progobj is None:
+            progobj = self.program_from_system(args)
+        if required and (progobj is None or not progobj.found()):
             raise InvalidArguments('Program "%s" not found or not executable' % exename)
+        if progobj is None:
+            return ExternalProgramHolder(dependencies.ExternalProgram('nonexistingprogram'))
         return progobj
 
     def func_find_library(self, node, args, kwargs):

run_unittests.py

@@ -1923,6 +1923,28 @@ class LinuxlikeTests(BasePlatformTests):
         self.run_tests()
         self.run_target('coverage-html')
 
+    def test_cross_find_program(self):
+        testdir = os.path.join(self.unit_test_dir, '12 cross prog')
+        crossfile = tempfile.NamedTemporaryFile(mode='w')
+        print(os.path.join(testdir, 'some_cross_tool.py'))
+        crossfile.write('''[binaries]
+c = '/usr/bin/cc'
+ar = '/usr/bin/ar'
+strip = '/usr/bin/ar'
+sometool.py = '%s'
+
+[properties]
+
+[host_machine]
+system = 'linux'
+cpu_family = 'arm'
+cpu = 'armv7' # Not sure if correct.
+endian = 'little'
+''' % os.path.join(testdir, 'some_cross_tool.py'))
+        crossfile.flush()
+        self.init(testdir, ['--cross-file='+crossfile.name])
+
+
 class LinuxArmCrossCompileTests(BasePlatformTests):
     '''
     Tests that verify cross-compilation to Linux/ARM

test cases/unit/12 cross prog/meson.build

@@ -0,0 +1,12 @@
+project('cross find program', 'c')
+
+native_exe = find_program('sometool.py', native : true)
+cross_exe = find_program('sometool.py')
+
+native_out = run_command(native_exe).stdout().strip()
+cross_out = run_command(cross_exe).stdout().strip()
+
+assert(native_out == 'native',
+  'Native output incorrect:' + native_out)
+assert(cross_out == 'cross',
+  'Cross output incorrect:' + cross_out)

test cases/unit/12 cross prog/some_cross_tool.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+print('cross')

test cases/unit/12 cross prog/sometool.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+print('native')