backends: Fix custom_target() with configure_file() exe

mesonbuild/backend/backends.py

@@ -408,6 +408,9 @@ class Backend:
             # common cases.
             exe_cmd = [self.get_target_filename_abs(exe)]
             exe_for_machine = MachineChoice.BUILD
+        elif isinstance(exe, mesonlib.File):
+            exe_cmd = [exe.rel_to_builddir(self.environment.source_dir)]
+            exe_for_machine = MachineChoice.BUILD
         else:
             exe_cmd = [exe]
             exe_for_machine = MachineChoice.BUILD

test cases/common/52 run target/meson.build

@@ -65,11 +65,14 @@ conf = configure_file(
   configuration: configuration_data()
 )
 
-
 run_target('configure_script',
   command : conf
 )
 
+custom_target('configure_script_ct',
+  command: conf,
+  output: 'dummy.txt',
+  capture: true)
 
 # Target names that clash with potential builtin functionality.
 run_target('ctags',