Merge pull request #4464 from joshuawarner32/fix-one_of

Fix one_of bug, properly return MadeProgress from "when" parsing

crates/compiler/parse/src/expr.rs

@@ -346,6 +346,7 @@ fn parse_expr_start<'a>(
         loc!(move |a, s, m| parse_expr_operator_chain(m, options, a, s)),
         fail_expr_start_e()
     ]
+    .trace("expr_start")
     .parse(arena, state, min_indent)
 }
 
@@ -2076,10 +2077,10 @@ mod when {
                     parser::keyword_e(keyword::IS, EWhen::Is)
                 )
             ),
-            move |arena, state, progress, (case_indent, loc_condition), min_indent| {
+            move |arena, state, _progress, (case_indent, loc_condition), min_indent| {
                 if case_indent < min_indent {
                     return Err((
-                        progress,
+                        MadeProgress,
                         // TODO maybe pass case_indent here?
                         EWhen::PatternAlignment(5, state.pos()),
                         state,
@@ -2089,15 +2090,18 @@ mod when {
                 // Everything in the branches must be indented at least as much as the case itself.
                 let min_indent = case_indent;
 
-                let (p1, branches, state) = branches(options).parse(arena, state, min_indent)?;
+                let (_p1, branches, state) = branches(options)
+                    .parse(arena, state, min_indent)
+                    .map_err(|(_p, e, s)| (MadeProgress, e, s))?;
 
                 Ok((
-                    progress.or(p1),
+                    MadeProgress,
                     Expr::When(arena.alloc(loc_condition), branches.into_bump_slice()),
                     state,
                 ))
             },
         )
+        .trace("when")
     }
 
     /// Parsing when with indentation.

crates/compiler/parse/src/parser.rs

@@ -737,6 +737,7 @@ pub trait Parser<'a, Output, Error> {
     ) -> ParseResult<'a, Output, Error>;
 
     #[cfg(not(feature = "parse_debug_trace"))]
+    #[inline(always)]
     fn trace(self, _message: &'static str) -> Self
     where
         Self: Sized,
@@ -789,7 +790,7 @@ impl<'a, O: std::fmt::Debug, E: std::fmt::Debug, P: Parser<'a, O, E>> Parser<'a,
 where
     E: 'a,
 {
-    fn parse(&self, arena: &'a Bump, state: State<'a>) -> ParseResult<'a, O, E> {
+    fn parse(&self, arena: &'a Bump, state: State<'a>, min_indent: u32) -> ParseResult<'a, O, E> {
         use std::cell::RefCell;
 
         thread_local! {
@@ -803,7 +804,7 @@ where
         let cur_indent = INDENT.with(|i| *i.borrow());
 
         println!(
-            "{:>5?}: {}{:<50}",
+            "{:<5?}: {}{:<50}",
             state.pos(),
             &indent_text[..cur_indent * 2],
             self.message
@@ -1379,11 +1380,12 @@ macro_rules! and {
 macro_rules! one_of {
     ($p1:expr, $p2:expr) => {
         move |arena: &'a bumpalo::Bump, state: $crate::state::State<'a>, min_indent: u32| {
+            let original_state = state.clone();
 
             match $p1.parse(arena, state, min_indent) {
                 valid @ Ok(_) => valid,
                 Err((MadeProgress, fail, state)) => Err((MadeProgress, fail, state)),
-                Err((NoProgress, _, state)) => $p2.parse(arena, state, min_indent),
+                Err((NoProgress, _, _)) => $p2.parse(arena, original_state, min_indent),
             }
         }
     };

crates/compiler/parse/tests/snapshots/fail/pattern_binds_keyword.expr.result-ast

@@ -0,0 +1 @@
+Expr(When(Condition(Start(@30), @29), @24), @0)

crates/compiler/parse/tests/snapshots/fail/pattern_binds_keyword.expr.roc

@@ -0,0 +1,6 @@
+when Just 4 is
+    Just when ->
+        4
+
+    _ ->
+        2

crates/compiler/parse/tests/snapshots/fail/when_missing_arrow.expr.result-ast

@@ -0,0 +1 @@
+Expr(When(Arrow(@26), @20), @0)

crates/compiler/parse/tests/snapshots/fail/when_missing_arrow.expr.roc

@@ -0,0 +1,3 @@
+when 5 is
+    1 -> 2
+    _

crates/compiler/parse/tests/test_parse.rs

@@ -124,6 +124,8 @@ mod test_parse {
         fail/lambda_missing_indent.expr,
         fail/type_argument_no_arrow.expr,
         fail/type_double_comma.expr,
+        fail/when_missing_arrow.expr,
+        fail/pattern_binds_keyword.expr,
         pass/ability_demand_signature_is_multiline.expr,
         pass/ability_multi_line.expr,
         pass/ability_single_line.expr,

crates/compiler/region/src/all.rs

@@ -133,7 +133,8 @@ impl Position {
 
 impl Debug for Position {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "@{}", self.offset)
+        write!(f, "@")?;
+        self.offset.fmt(f)
     }
 }
 

crates/reporting/tests/test_reporting.rs

@@ -4847,14 +4847,27 @@ mod test_reporting {
             "#
         ),
         @r###"
-    ── MISSING EXPRESSION ───────────────────── tmp/pattern_binds_keyword/Test.roc ─
+    ── MISSING ARROW ────────────────────────── tmp/pattern_binds_keyword/Test.roc ─
 
-    I am partway through parsing a `when` expression, but I got stuck here:
+    I am partway through parsing a `when` expression, but got stuck here:
 
     5│          Just when ->
                      ^
 
-    I was expecting to see an expression like 42 or "hello".
+    I was expecting to see an arrow next.
+
+    Note: Sometimes I get confused by indentation, so try to make your `when`
+    look something like this:
+
+        when List.first plants is
+          Ok n ->
+            n
+
+          Err _ ->
+            200
+
+    Notice the indentation. All patterns are aligned, and each branch is
+    indented a bit more than the corresponding pattern. That is important!
     "###
     );