Hint on type error on int operators

Changes

@@ -69,6 +69,10 @@ Working version
   (Jules Aguillon, review by Nicolás Ojeda Bär , Florian Angeletti,
   Gabriel Scherer and Armaël Guéneau)
 
+- GPR#2307: Hint on type error on int's operators
+  (Jules Aguillon, with help from Armaël Guéneau,
+   review by Gabriel Scherer and Florian Angeletti)
+
 ### Bug fixes:
 
 - MPR#7937, GPR#2287: fix uncaught Unify exception when looking for type

testsuite/tests/tool-caml-tex/redirections.reference

@@ -18,9 +18,10 @@
 \camlexample{toplevel}
 \caml\camlinput\?[@@@warning "+A"];;
 \endcamlinput\endcaml
-\caml\camlinput\?1 + \<2.\> ;;
+\caml\camlinput\?1 \<+\> \<2.\> ;;
 \endcamlinput\camlerror\:Error: This expression has type float but an expression was expected of type
 \:         int
+\:  Hint: Did you mean to use \textasciigrave\-+.\textquotesingle\-?
 \endcamlerror\endcaml
 \caml\camlinput\?let f \<x\> = () ;;
 \endcamlinput\camlwarn\:Warning 27: unused variable x.

testsuite/tests/typing-core-bugs/int_operator_hint.ml

@@ -0,0 +1,79 @@
+(* TEST
+   * expect
+*)
+
+let _ = 0. + 0.
+[%%expect{|
+Line 1, characters 8-10:
+1 | let _ = 0. + 0.
+            ^^
+Error: This expression has type float but an expression was expected of type
+         int
+Line 1, characters 11-12:
+1 | let _ = 0. + 0.
+               ^
+  Hint: Did you mean to use `+.'?
+|}]
+
+let _ = 0l - 0l
+[%%expect{|
+Line 1, characters 8-10:
+1 | let _ = 0l - 0l
+            ^^
+Error: This expression has type int32 but an expression was expected of type
+         int
+Line 1, characters 11-12:
+1 | let _ = 0l - 0l
+               ^
+  Hint: Did you mean to use `Int32.sub'?
+|}]
+
+let _ = 0L * 0L
+[%%expect{|
+Line 1, characters 8-10:
+1 | let _ = 0L * 0L
+            ^^
+Error: This expression has type int64 but an expression was expected of type
+         int
+Line 1, characters 11-12:
+1 | let _ = 0L * 0L
+               ^
+  Hint: Did you mean to use `Int64.mul'?
+|}]
+
+let _ = 0n / 0n
+[%%expect{|
+Line 1, characters 8-10:
+1 | let _ = 0n / 0n
+            ^^
+Error: This expression has type nativeint
+       but an expression was expected of type int
+Line 1, characters 11-12:
+1 | let _ = 0n / 0n
+               ^
+  Hint: Did you mean to use `Nativeint.div'?
+|}]
+
+let _ = 0. mod 0.
+[%%expect{|
+Line 1, characters 8-10:
+1 | let _ = 0. mod 0.
+            ^^
+Error: This expression has type float but an expression was expected of type
+         int
+Line 1, characters 11-14:
+1 | let _ = 0. mod 0.
+               ^^^
+  Hint: Did you mean to use `Float.rem'?
+|}]
+
+(* disabled *)
+let _ = 0 +. 0
+[%%expect{|
+Line 1, characters 8-9:
+1 | let _ = 0 +. 0
+            ^
+Error: This expression has type int but an expression was expected of type
+         float
+       Hint: Did you mean `0.'?
+|}]

testsuite/tests/typing-core-bugs/ocamltests

@@ -3,3 +3,4 @@ unit_fun_hints.ml
 type_expected_explanation.ml
 repeated_did_you_mean.ml
 const_int_hint.ml
+int_operator_hint.ml

tools/caml_tex.ml

@@ -132,10 +132,12 @@ module Toplevel = struct
     if startchar >= 0 then
       locs := (startchar, endchar) :: !locs
 
-  (** Record the main location instead of printing it *)
+  (** Record locations in the main error and suberrors without printing them *)
   let printer_register_locs =
     { Location.batch_mode_printer with
-      pp_main_loc = (fun _ _ _ loc -> register_loc loc) }
+      pp_main_loc = (fun _ _ _ loc -> register_loc loc);
+      pp_submsg_loc = (fun _ _ _ loc -> register_loc loc);
+    }
 
   (** Capture warnings and keep them in a list *)
   let warnings = ref []