Add variables to test to prove linkage is correct.

test cases/common/160 duplicate source names/dir1/file.c

@@ -1 +1,16 @@
-int main() { return 0; }
+extern int dir2;
+extern int dir2_dir1;
+extern int dir3;
+extern int dir3_dir1;
+
+int main() {
+    if (dir2 != 20)
+        return 1;
+    if (dir2_dir1 != 21)
+        return 1;
+    if (dir3 != 30)
+        return 1;
+    if (dir3_dir1 != 31)
+        return 1;
+    return 0;
+}

test cases/common/160 duplicate source names/dir2/dir1/file.c

@@ -0,0 +1 @@
+int dir2_dir1 = 21;

test cases/common/160 duplicate source names/dir2/file.c

@@ -0,0 +1 @@
+int dir2 = 20;

test cases/common/160 duplicate source names/dir3/dir1/file.c

@@ -0,0 +1 @@
+int dir3_dir1 = 31;

test cases/common/160 duplicate source names/dir3/file.c

@@ -0,0 +1 @@
+int dir3 = 30;

test cases/common/160 duplicate source names/dir3/meson.build

@@ -1 +1 @@
-lib = static_library('empty', 'file.c', 'dir1/file.c')
+lib = static_library('lib', 'file.c', 'dir1/file.c')

test cases/common/160 duplicate source names/meson.build

@@ -4,4 +4,4 @@ sources = []
 subdir('dir1')
 subdir('dir2')
 subdir('dir3')
-executable('a.out', sources : sources, objects : lib.extract_objects())
+executable('a.out', sources : sources, objects : lib.extract_all_objects())