--- mif1.c~
+++ mif1.c
@@ -5,19 +5,13 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#if FOO
+#line 9 "mif1.c"
 int foo() { return 0; }
-#else
-#error FOO not defined
-#endif
+#line 13 "mif1.c"
 
-#if BAR
-int foo() { return 0; }
-#elif FOO
+#line 17 "mif1.c"
 int bar() { return 0; }
-#else
-#error FOO not defined
-#endif
+#line 21 "mif1.c"
 
 int main()
 {
--- mif2.c~
+++ mif2.c
@@ -5,11 +5,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#if defined(FOO)
+#line 9 "mif2.c"
 int foo() { return 0; }
-#else
-#error FOO not defined
-#endif
+#line 13 "mif2.c"
 
 int main()
 {