Calculate target paths correctly when workdir is set.

mesonbuild/backend/backends.py

@@ -725,7 +725,7 @@ class Backend:
                 elif isinstance(a, str):
                     cmd_args.append(a)
                 elif isinstance(a, build.Target):
-                    cmd_args.append(self.get_target_filename(a))
+                    cmd_args.append(self.construct_target_rel_path(a, t.workdir))
                 else:
                     raise MesonException('Bad object in test command.')
             ts = TestSerialisation(t.get_name(), t.project_name, t.suite, cmd, is_cross,
@@ -737,6 +737,13 @@ class Backend:
     def write_test_serialisation(self, tests, datafile):
         pickle.dump(self.create_test_serialisation(tests), datafile)
 
+    def construct_target_rel_path(self, a, workdir):
+        if workdir is None:
+            return self.get_target_filename(a)
+        assert(os.path.isabs(workdir))
+        abs_path = self.get_target_filename_abs(a)
+        return os.path.relpath(abs_path, workdir)
+
     def generate_depmf_install(self, d):
         if self.build.dep_manifest_name is None:
             return

test cases/common/97 test workdir/meson.build

@@ -4,3 +4,5 @@ exe = executable('opener', 'opener.c')
 
 test('basic', exe, workdir : meson.source_root())
 test('shouldfail', exe, should_fail : true)
+
+subdir('subdir')

test cases/common/97 test workdir/subdir/checker.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python3
+
+import sys
+
+data = open(sys.argv[1], 'rb').read()

test cases/common/97 test workdir/subdir/meson.build

@@ -0,0 +1,4 @@
+exe2 = executable('dummy', '../opener.c')
+test('subdir', find_program('checker.py'),
+  workdir : meson.source_root(),
+  args: [exe2])