chore(compiler): Improve unsafe equality warning (#1892)

Co-authored-by: Blaine Bublitz <blaine.bublitz@gmail.com>

Author: spotandjake

compiler/src/typed/typed_well_formedness.re

@@ -37,6 +37,23 @@ let rec exp_is_wasm_unsafe = ({exp_type}) => {
   };
   type_is_wasm_unsafe(exp_type);
 };
+let rec resolve_unsafe_type = ({exp_type}) => {
+  let rec type_is_wasm_unsafe = t => {
+    switch (t.desc) {
+    | TTyConstr(path, _, _) =>
+      switch (path) {
+      | t when t == Builtin_types.path_wasmi32 => "WasmI32"
+      | t when t == Builtin_types.path_wasmi64 => "WasmI64"
+      | t when t == Builtin_types.path_wasmf32 => "WasmF32"
+      | t when t == Builtin_types.path_wasmf64 => "WasmI64"
+      | _ => failwith("Impossible: type cannot be a wasm unsafe value")
+      }
+    | TTyLink(t) => type_is_wasm_unsafe(t)
+    | _ => failwith("Impossible: type cannot be a wasm unsafe value")
+    };
+  };
+  type_is_wasm_unsafe(exp_type);
+};
 
 let is_marked_unsafe = attrs => {
   // Disable_gc implies Unsafe
@@ -228,9 +245,16 @@ module WellFormednessArg: TypedtreeIter.IteratorArgument = {
         )
           when func == "==" || func == "!=" =>
         if (List.exists(((_, arg)) => exp_is_wasm_unsafe(arg), args)) {
+          let typeName =
+            switch (args) {
+            | [(_, arg), _] => resolve_unsafe_type(arg)
+            | _ => "(WasmI32 | WasmI64 | WasmF32 | WasmF64)"
+            };
           let warning =
             Grain_utils.Warnings.FuncWasmUnsafe(
               Printf.sprintf("Pervasives.(%s)", func),
+              Printf.sprintf("%s.(%s)", typeName, func),
+              typeName,
             );
           if (Grain_utils.Warnings.is_active(warning)) {
             Grain_parsing.Location.prerr_warning(exp_loc, warning);

compiler/src/utils/warnings.re

@@ -23,7 +23,7 @@ type t =
   | UnreachableCase
   | ShadowConstructor(string)
   | NoCmiFile(string, option(string))
-  | FuncWasmUnsafe(string)
+  | FuncWasmUnsafe(string, string, string)
   | FromNumberLiteralI32(string)
   | FromNumberLiteralI64(string)
   | FromNumberLiteralU32(string)
@@ -52,7 +52,7 @@ let number =
   | NoCmiFile(_) => 14
   | NonClosedRecordPattern(_) => 15
   | UnusedExtension => 16
-  | FuncWasmUnsafe(_) => 17
+  | FuncWasmUnsafe(_, _, _) => 17
   | FromNumberLiteralI32(_) => 18
   | FromNumberLiteralI64(_) => 19
   | FromNumberLiteralU32(_) => 20
@@ -119,10 +119,14 @@ let message =
     )
   | NonClosedRecordPattern(s) =>
     "the following fields are missing from the record pattern: " ++ s
-  | FuncWasmUnsafe(func) =>
+  | FuncWasmUnsafe(func, f, m) =>
     "it looks like you are using "
     ++ func
-    ++ " on two unsafe Wasm values here.\nThis is generally unsafe and will cause errors. Use one of the equivalent functions in `WasmI32`, `WasmI64`, `WasmF32`, or `WasmF64` instead."
+    ++ " on two unsafe Wasm values here.\nThis is generally unsafe and will cause errors. Use "
+    ++ f
+    ++ " from the `"
+    ++ m
+    ++ "` module the instead."
   | FromNumberLiteralI32(n) =>
     Printf.sprintf(
       "it looks like you are calling Int32.fromNumber() with a constant number. Try using the literal syntax (e.g. `%sl`) instead.",
@@ -195,7 +199,7 @@ let defaults = [
   UnreachableCase,
   ShadowConstructor(""),
   NoCmiFile("", None),
-  FuncWasmUnsafe(""),
+  FuncWasmUnsafe("", "", ""),
   FromNumberLiteralI32(""),
   FromNumberLiteralI64(""),
   FromNumberLiteralU32(""),

compiler/src/utils/warnings.rei

@@ -37,7 +37,7 @@ type t =
   | UnreachableCase
   | ShadowConstructor(string)
   | NoCmiFile(string, option(string))
-  | FuncWasmUnsafe(string)
+  | FuncWasmUnsafe(string, string, string)
   | FromNumberLiteralI32(string)
   | FromNumberLiteralI64(string)
   | FromNumberLiteralU32(string)