find_program: Support passing mesonlib.File objects

This means you can pass files() and the return value of configure_file()
to find_program() now.

mesonbuild/interpreter.py

@@ -1759,7 +1759,6 @@ class Interpreter(InterpreterBase):
                     break
             self.coredata.base_options[optname] = oobj
 
-    @stringArgs
     def func_find_program(self, node, args, kwargs):
         if len(args) == 0:
             raise InterpreterException('No program name specified.')
@@ -1769,8 +1768,21 @@ class Interpreter(InterpreterBase):
         # 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.
-        search_dir = os.path.join(self.environment.get_source_dir(), self.subdir)
+        source_dir = os.path.join(self.environment.get_source_dir(), self.subdir)
         for exename in args:
+            if isinstance(exename, mesonlib.File):
+                if exename.is_built:
+                    search_dir = os.path.join(self.environment.get_build_dir(),
+                                              exename.subdir)
+                else:
+                    search_dir = os.path.join(self.environment.get_source_dir(),
+                                              exename.subdir)
+                exename = exename.fname
+            elif isinstance(exename, str):
+                search_dir = source_dir
+            else:
+                raise InvalidArguments('find_program only accepts strings and '
+                                       'files, not {!r}'.format(exename))
             extprog = dependencies.ExternalProgram(exename, search_dir=search_dir)
             progobj = ExternalProgramHolder(extprog)
             if progobj.found():

test cases/common/105 find program path/meson.build

@@ -8,3 +8,11 @@ if not python.found()
 endif
 
 run_command(python, prog.path())
+
+progf = files('program.py')
+py = configure_file(input : 'program.py',
+                    output : 'builtprogram.py',
+                    configuration : configuration_data())
+
+find_program(py)
+find_program(progf)