Source map: repeat mappings over new lines

Firefox assumes that a mapping stops at the end of a line, which is inconvenient. When this happens, we repeat the mapping on the next line.
ocsigen · Oct 18, 2024 · 4494d81 · 4494d81
1 parent 880ceb1
commit 4494d81
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Showing 3 changed files with 41 additions and 15 deletions.
diff --git a/compiler/lib/js_output.ml b/compiler/lib/js_output.ml
@@ -2154,22 +2154,45 @@ let program ?(accept_unnamed_var = false) f ?source_map p =
  String.length filename >= 9 && String.sub filename 0 9 = "/builtin/")
  in
  let sm_mappings = Source_map.Mappings.decode sm.mappings in
- let mappings =
- List.rev_append_map !temp_mappings sm_mappings ~f:(fun (pos, m) ->
- let gen_line = pos.PP.p_line + 1 in
- let gen_col = pos.PP.p_col in
- match m with
- | Source_map.Gen { gen_col = _; gen_line = _ } ->
- Source_map.Gen { gen_col; gen_line }
- | Source_map.Gen_Ori
- { gen_line = _; gen_col = _; ori_source; ori_line; ori_col } ->
- Source_map.Gen_Ori { gen_line; gen_col; ori_source; ori_line; ori_col }
- | Source_map.Gen_Ori_Name
- { gen_line = _; gen_col = _; ori_source; ori_line; ori_col; ori_name }
- ->
- Source_map.Gen_Ori_Name
- { gen_line; gen_col; ori_source; ori_line; ori_col; ori_name })
+ let relocate pos m =
+ let gen_line = pos.PP.p_line + 1 in
+ let gen_col = pos.PP.p_col in
+ match m with
+ | Source_map.Gen { gen_col = _; gen_line = _ } ->
+ Source_map.Gen { gen_col; gen_line }
+ | Source_map.Gen_Ori m -> Source_map.Gen_Ori { m with gen_line; gen_col }
+ | Source_map.Gen_Ori_Name m ->
+ Source_map.Gen_Ori_Name { m with gen_line; gen_col }
+ in
+ let prepend mapping prev_mappings =
+ let rec prepend_rec pos mapping prev_mappings =
+ match mapping with
+ | [] -> prev_mappings
+ | (pos', m) :: rem ->
+ (*
+ Format.eprintf
+ "%d,%d %d,%d@."
+ pos'.PP.p_line
+ pos'.PP.p_col
+ pos.PP.p_line
+ pos.PP.p_col;
+*)
+ if pos'.PP.p_line = pos.PP.p_line
+ || (pos'.p_line = pos.p_line - 1 && pos.p_col = 0)
+ then prepend_rec pos' rem (relocate pos' m :: prev_mappings)
+ else if pos.p_col > 0
+ then
+ let pos = { pos with p_col = 0 } in
+ prepend_rec pos mapping (relocate pos m :: prev_mappings)
+ else
+ let pos = { pos with p_line = pos.p_line - 1 } in
+ prepend_rec pos mapping (relocate pos m :: prev_mappings)
+ in
+ match mapping with
+ | [] -> prev_mappings
+ | (pos, m) :: rem -> prepend_rec pos rem (relocate pos m :: prev_mappings)
  in
+ let mappings = prepend !temp_mappings sm_mappings in
  let mappings = Source_map.Mappings.encode mappings in
  Some
  { sm with

diff --git a/compiler/tests-compiler/sourcemap.ml b/compiler/tests-compiler/sourcemap.ml
@@ -84,10 +84,12 @@ let%expect_test _ =
  13: //# sourceMappingURL=test.map
  /builtin/blackbox.ml:1:0 -> 5:7
  /builtin/blackbox.ml:1:0 -> 5:17
+ /builtin/blackbox.ml:1:0 -> 6:0
  /dune-root/test.ml:1:4 -> 6:12
  /dune-root/test.ml:1:7 -> 6:15
  /dune-root/test.ml:1:11 -> 6:18
  /dune-root/test.ml:1:12 -> 6:28
+ /dune-root/test.ml:1:12 -> 7:0
  /dune-root/test.ml:1:12 -> 7:7
  /builtin/blackbox.ml:1:0 -> 7:14
  |}]

diff --git a/compiler/tests-sourcemap/dump.reference b/compiler/tests-sourcemap/dump.reference
@@ -3,4 +3,5 @@ sourcemap for test.bc.js
 /my/sourceRoot#b.ml:1:6 -> 14: function f(<>x){return x - 1 | 0; }
 /my/sourceRoot#b.ml:1:10 -> 17: function f(x){<>return x - 1 | 0; }
 /my/sourceRoot#b.ml:1:15 -> 35: function f(x){return x - 1 | 0; <>}
+/my/sourceRoot#b.ml:1:15 -> 0:<> var Testlib_B = [0, f];
 /my/sourceRoot#b.ml:1:15 -> 7: var <>Testlib_B = [0, f];