Fix error reporting location for unterminated strings and add test for insufficiently indented multiline strings

crates/compiler/parse/src/string_literal.rs

@@ -170,7 +170,11 @@ pub fn parse<'a>() -> impl Parser<'a, StrLiteral<'a>, EString<'a>> {
 
         let indent = state.column();
 
+        let start_state;
+
         if state.consume_mut("\"\"\"") {
+            start_state = state.clone();
+
             // we will be parsing a multi-line string
             is_multiline = true;
 
@@ -178,6 +182,8 @@ pub fn parse<'a>() -> impl Parser<'a, StrLiteral<'a>, EString<'a>> {
                 state = consume_indent(state, indent)?;
             }
         } else if state.consume_mut("\"") {
+            start_state = state.clone();
+
             // we will be parsing a single-line string
             is_multiline = false;
         } else {
@@ -331,7 +337,11 @@ pub fn parse<'a>() -> impl Parser<'a, StrLiteral<'a>, EString<'a>> {
                         // all remaining chars. This will mask all other errors, but
                         // it should make it easiest to debug; the file will be a giant
                         // error starting from where the open quote appeared.
-                        return Err((MadeProgress, EString::EndlessSingle(state.pos()), state));
+                        return Err((
+                            MadeProgress,
+                            EString::EndlessSingle(start_state.pos()),
+                            start_state,
+                        ));
                     }
                 }
                 b'\\' => {
@@ -434,11 +444,11 @@ pub fn parse<'a>() -> impl Parser<'a, StrLiteral<'a>, EString<'a>> {
         Err((
             MadeProgress,
             if is_multiline {
-                EString::EndlessMulti(state.pos())
+                EString::EndlessMulti(start_state.pos())
             } else {
-                EString::EndlessSingle(state.pos())
+                EString::EndlessSingle(start_state.pos())
             },
-            state,
+            start_state,
         ))
     }
 }

crates/reporting/src/error/parse.rs

@@ -921,6 +921,27 @@ fn to_str_report<'a>(
                 severity: Severity::RuntimeError,
             }
         }
+        EString::MultilineInsufficientIndent(pos) => {
+            let surroundings = Region::new(start, pos);
+            let region = LineColumnRegion::from_pos(lines.convert_pos(pos));
+
+            let doc = alloc.stack([
+                alloc.reflow(r"This multiline string is not sufficiently indented:"),
+                alloc.region_with_subregion(lines.convert_region(surroundings), region),
+                alloc.concat([
+                    alloc.reflow(r"Lines in a multi-line string must be indented at least as "),
+                    alloc.reflow("much as the beginning \"\"\". This extra indentation is automatically removed "),
+                    alloc.reflow("from the string during compilation."),
+                ]),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "INSUFFICIENT INDENT IN MULTI-LINE STRING".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
     }
 }
 fn to_expr_in_parens_report<'a>(

crates/reporting/tests/test_reporting.rs

@@ -5215,6 +5215,23 @@ mod test_reporting {
     "###
     );
 
+    test_report!(
+        multi_insufficient_indent,
+        "    \"\"\"\n  testing\n    \"\"\"", // 4 space indent on the start, 2 space on the `testing` line
+        @r###"
+    ── INSUFFICIENT INDENT IN MULTI-LINE STRING ─ ..._insufficient_indent/Test.roc ─
+
+    This multiline string is not sufficiently indented:
+
+    5│        testing
+              ^
+
+    Lines in a multi-line string must be indented at least as much as the
+    beginning """. This extra indentation is automatically removed from
+    the string during compilation.
+    "###
+    );
+
     // https://github.com/rtfeldman/roc/issues/1714
     test_report!(
     interpolate_concat_is_transparent_1714,