Compiler: fix sourcemap merging

Author: hhugo

compiler/lib/source_map.ml

@@ -104,7 +104,7 @@ let string_of_mapping mapping =
         let l =
           (c.gen_col - !gen_col)
           ::
-          (if c.ori_source = -1
+          (if c.ori_source < 0
            then []
            else
              (c.ori_source - !ori_source)
@@ -119,7 +119,7 @@ let string_of_mapping mapping =
                  [ n - n' ]))
         in
         gen_col := c.gen_col;
-        if c.ori_source <> -1
+        if c.ori_source >= 0
         then (
           ori_source := c.ori_source;
           ori_line := c.ori_line;
@@ -199,7 +199,9 @@ let mapping_of_string str =
 
 let maps ~sources_offset ~names_offset x =
   let gen_line = x.gen_line in
-  let ori_source = x.ori_source + sources_offset in
+  let ori_source =
+    if x.ori_source < 0 then x.ori_source else x.ori_source + sources_offset
+  in
   let ori_name =
     match x.ori_name with
     | None -> None

compiler/tests-sourcemap/dump.reference

@@ -5,6 +5,3 @@ b.ml:1:10 -> 17:   function f(x){<>return x - 1 | 0;}
 b.ml:1:6 -> 24:   function f(x){return <>x - 1 | 0;}
 b.ml:1:15 -> 34:   function f(x){return x - 1 | 0;<>}
 b.ml:1:4 -> 23:   var Testlib_B = [0, <>f];
-d.ml:-1:-1 -> 2:  <>}
-a.ml:-1:-1 -> 3:   <>function caml_call1(f, a0){
-a.ml:-1:-1 -> 2:  <>}