do not suggest coercion for constant expressions

Author: zth

compiler/ml/error_message_utils.ml

@@ -373,7 +373,16 @@ let print_extra_type_clash_help ~extract_concrete_typedecl ~env loc ppf
       | structure, comments -> Some (!Parser.reprint_source structure comments)
     in
 
-    if is_subtype then (
+    (* Suggesting coercion only makes sense for non-constant values. *)
+    let is_constant =
+      match !Parser.parse_source target_expr_text with
+      | ( [{Parsetree.pstr_desc = Pstr_eval ({pexp_desc = Pexp_constant _}, _)}],
+          _ ) ->
+        true
+      | _ -> false
+    in
+
+    if is_subtype && not is_constant then (
       fprintf ppf
         "@,\
          @,\

tests/build_tests/super_errors/expected/primitives1.res.expected

@@ -9,11 +9,5 @@
   This has type: int
   But it's expected to have type: float
 
-  Possible solutions: 
-  - These types are compatible at runtime. You can use the coercion operator :> to convert to the expected type float.
-    If you want to use coercion, rewrite the highlighted code to: (2 :> float)
-
-  
-  
   You can convert int to float with Int.toFloat.
   If this is a literal, try a number with a trailing dot (e.g. 20.).

tests/build_tests/super_errors/expected/primitives6.res.expected

@@ -10,11 +10,5 @@
   This has type: int
   But it's expected to have type: float
 
-  Possible solutions: 
-  - These types are compatible at runtime. You can use the coercion operator :> to convert to the expected type float.
-    If you want to use coercion, rewrite the highlighted code to: (10 :> float)
-
-  
-  
   You can convert int to float with Int.toFloat.
   If this is a literal, try a number with a trailing dot (e.g. 20.).

tests/build_tests/super_errors/expected/type1.res.expected

@@ -8,11 +8,5 @@
   This has type: int
   But it's expected to have type: float
 
-  Possible solutions: 
-  - These types are compatible at runtime. You can use the coercion operator :> to convert to the expected type float.
-    If you want to use coercion, rewrite the highlighted code to: (2 :> float)
-
-  
-  
   You can convert int to float with Int.toFloat.
   If this is a literal, try a number with a trailing dot (e.g. 20.).