Report type alias issues

reporting/src/error/parse.rs

@@ -1907,6 +1907,7 @@ fn to_type_report<'a>(
         EType::TTagUnion(tag_union, pos) => to_ttag_union_report(alloc, filename, tag_union, *pos),
         EType::TInParens(tinparens, pos) => to_tinparens_report(alloc, filename, tinparens, *pos),
         EType::TApply(tapply, pos) => to_tapply_report(alloc, filename, tapply, *pos),
+        EType::TInlineAlias(talias, _) => to_talias_report(alloc, filename, talias),
 
         EType::TFunctionArgument(pos) => match what_is_next(alloc.src_lines, *pos) {
             Next::Other(Some(',')) => {
@@ -2816,6 +2817,75 @@ fn to_tapply_report<'a>(
     }
 }
 
+fn to_talias_report<'a>(
+    alloc: &'a RocDocAllocator<'a>,
+    filename: PathBuf,
+    parse_problem: &roc_parse::parser::ETypeInlineAlias,
+) -> Report<'a> {
+    use roc_parse::parser::ETypeInlineAlias;
+
+    match *parse_problem {
+        ETypeInlineAlias::NotAnAlias(pos) => {
+            let region = Region::from_pos(pos);
+
+            let doc = alloc.stack(vec![
+                alloc.concat(vec![
+                    alloc.reflow("The inline type after this "),
+                    alloc.keyword("as"),
+                    alloc.reflow(" is not a type alias:"),
+                ]),
+                alloc.region(region),
+                alloc.concat(vec![
+                    alloc.reflow("Inline alias types must start with an uppercase identifier and be followed by zero or more type arguments, like "),
+                    alloc.type_str("Point"),
+                    alloc.reflow(" or "),
+                    alloc.type_str("List a"),
+                    alloc.reflow("."),
+                ]),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "NOT AN INLINE ALIAS".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
+        ETypeInlineAlias::Qualified(pos) => {
+            let region = Region::from_pos(pos);
+
+            let doc = alloc.stack(vec![
+                alloc.reflow(r"This type alias has a qualified name:"),
+                alloc.region(region),
+                alloc.reflow("Alias can't be qualified."),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "QUALIFIED ALIAS NAME".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
+        ETypeInlineAlias::ArgumentNotLowercase(pos) => {
+            let region = Region::from_pos(pos);
+
+            let doc = alloc.stack(vec![
+                alloc.reflow(r"This alias type argument is not lowercase:"),
+                alloc.region(region),
+                alloc.reflow("All type arguments must be lowercase."),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "TYPE ARGUMENT NOT LOWERCASE".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
+    }
+}
+
 fn to_header_report<'a>(
     alloc: &'a RocDocAllocator<'a>,
     filename: PathBuf,

reporting/tests/test_reporting.rs

@@ -6913,4 +6913,74 @@ I need all branches in an `if` to have the same type!
             ),
         )
     }
+
+    #[test]
+    fn error_inline_alias_not_an_alias() {
+        report_problem_as(
+            indoc!(
+                r#"
+                f : List elem -> [ Nil, Cons elem a ] as a
+                "#
+            ),
+            indoc!(
+                r#"
+                ── NOT AN INLINE ALIAS ─────────────────────────────────────────────────────────
+
+                The inline type after this `as` is not a type alias:
+
+                1│  f : List elem -> [ Nil, Cons elem a ] as a
+                                                             ^
+
+                Inline alias types must start with an uppercase identifier and be
+                followed by zero or more type arguments, like Point or List a.
+                "#
+            ),
+        )
+    }
+
+    #[test]
+    fn error_inline_alias_qualified() {
+        report_problem_as(
+            indoc!(
+                r#"
+                f : List elem -> [ Nil, Cons elem a ] as Module.LinkedList a
+                "#
+            ),
+            indoc!(
+                r#"
+                ── QUALIFIED ALIAS NAME ────────────────────────────────────────────────────────
+
+                This type alias has a qualified name:
+
+                1│  f : List elem -> [ Nil, Cons elem a ] as Module.LinkedList a
+                                                             ^
+
+                Alias can't be qualified.
+                "#
+            ),
+        )
+    }
+
+    #[test]
+    fn error_inline_alias_argument_uppercase() {
+        report_problem_as(
+            indoc!(
+                r#"
+                f : List elem -> [ Nil, Cons elem a ] as LinkedList U
+                "#
+            ),
+            indoc!(
+                r#"
+                ── TYPE ARGUMENT NOT LOWERCASE ─────────────────────────────────────────────────
+
+                This alias type argument is not lowercase:
+
+                1│  f : List elem -> [ Nil, Cons elem a ] as LinkedList U
+                                                                        ^
+
+                All type arguments must be lowercase.
+                "#
+            ),
+        )
+    }
 }