fix line number off-by-one-error

src/loader/odoc_loader.ml

@@ -4,7 +4,7 @@ module Error = Odoc_model.Error
 let read_string parent_definition filename text =
   let location =
     let pos =
-      Lexing.{ pos_fname = filename; pos_lnum = 0; pos_cnum = 0; pos_bol = 0 }
+      Lexing.{ pos_fname = filename; pos_lnum = 1; pos_cnum = 0; pos_bol = 0 }
     in
     Location.{ loc_start = pos; loc_end = pos; loc_ghost = true }
   in

test/integration/compile.t/line_numbers.mld

@@ -0,0 +1,32 @@
+{0 line numbers}
+{[]}
+
+
+
+
+
+{Bad Markup}
+
+
+
+
+
+
+
+{6 heading}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+{syntax error

test/integration/compile.t/run.t

@@ -168,3 +168,17 @@ Compiling a '.cmt' file.
 
   $ ocamlc -bin-annot -c impl_only.ml
   $ odoc compile --package foo impl_only.cmt
+
+Check line numbers for errors in a '.mld' file.
+
+  $ odoc compile line_numbers.mld
+  File "line_numbers.mld", line 2, characters 0-4:
+  '{[...]}' (code block) should not be empty.
+  File "line_numbers.mld", line 8, characters 0-12:
+  '{Bad Markup}': bad markup.
+  Suggestion: did you mean '{!Bad Markup}' or '[Bad Markup]'?
+  File "line_numbers.mld", line 32, characters 0-1:
+  '{': bad markup.
+  Suggestion: escape the brace with '\{'.
+  File "line_numbers.mld", line 16, characters 0-11:
+  '6': bad heading level (0-5 allowed).