record update value

compiler/constrain/src/expr.rs

@@ -181,9 +181,10 @@ pub fn constrain_expr(
                 region,
             );
 
-            cons.push(con);
-            cons.push(fields_con);
-            cons.push(record_con);
+            // ensure constraints are solved in this order, gives better errors
+            cons.insert(0, fields_con);
+            cons.insert(1, con);
+            cons.insert(2, record_con);
 
             exists(vars, And(cons))
         }

compiler/reporting/src/report.rs

@@ -302,11 +302,11 @@ where
             Url => {
                 self.write_str("<")?;
             }
-            GlobalTag | PrivateTag | RecordField | Keyword => {
+            GlobalTag | PrivateTag | Keyword => {
                 self.write_str("`")?;
             }
             CodeBlock | PlainText | LineNumber | Error | GutterBar | TypeVariable | Alias
-            | Module | Structure | Symbol | BinOp => {}
+            | RecordField | Module | Structure | Symbol | BinOp => {}
         }
         self.style_stack.push(*annotation);
         Ok(())
@@ -324,11 +324,11 @@ where
                 Url => {
                     self.write_str(">")?;
                 }
-                GlobalTag | PrivateTag | RecordField | Keyword => {
+                GlobalTag | PrivateTag | Keyword => {
                     self.write_str("`")?;
                 }
                 CodeBlock | PlainText | LineNumber | Error | GutterBar | TypeVariable | Alias
-                | Module | Structure | Symbol | BinOp => {}
+                | RecordField | Module | Structure | Symbol | BinOp => {}
             },
         }
         Ok(())

compiler/reporting/src/type_error.rs

@@ -121,7 +121,7 @@ fn to_expr_report(
     use ReportText::*;
 
     match expected {
-        Expected::NoExpectation(_expected_type) => todo!(),
+        Expected::NoExpectation(expected_type) => todo!("hit no expectation with type {:?}", expected_type),
         Expected::FromAnnotation(_name, _arity, _sub_context, _expected_type) => todo!(),
         Expected::ForReason(reason, expected_type, region) => match reason {
             Reason::IfCondition => {
@@ -298,6 +298,26 @@ fn to_expr_report(
                     plain_text("instead. I need all elements of a list to have the same type!"),
                 )
             }
+            Reason::RecordUpdateValue(field) => report_mismatch(
+                filename,
+                &category,
+                found,
+                expected_type,
+                region,
+                Some(expr_region),
+                Concat(vec![
+                    plain_text("I cannot update the "),
+                    record_field_text(field.as_str()),
+                    plain_text(" field like this"),
+                ]),
+                Concat(vec![
+                    plain_text("You are trying to update "),
+                    record_field_text(field.as_str()),
+                    plain_text(" to be"),
+                ]),
+                plain_text("But it should be"),
+                plain_text("instead. Record update syntax does not allow you to change the type of fields. You can achieve that with record literal syntax."),
+            ),
             other => {
                 //    AnonymousFnArg { arg_index: u8 },
                 //    NamedFnArg(String /* function name */, u8 /* arg index */),

compiler/reporting/tests/test_reporting.rs

@@ -928,6 +928,38 @@ mod test_reporting {
         )
     }
 
+    #[test]
+    fn record_update_value() {
+        report_problem_as(
+            indoc!(
+                r#"
+                x : { foo : {} }
+                x = { foo: {} }
+
+                { x & foo: "bar" }
+                "#
+            ),
+            indoc!(
+                r#"
+                I cannot update the .foo field like this
+
+                4 ┆  { x & foo: "bar" }
+                  ┆  ^^^^^^^^^^^^^^^^^^
+
+                You are trying to update .foo to be a string of type
+
+                    Str
+
+                But it should be
+
+                    {}
+
+                instead. Record update syntax does not allow you to change the type of fields. You can achieve that with record literal syntax.
+                "#
+            ),
+        )
+    }
+
     #[test]
     fn circular_type() {
         report_problem_as(