Improve error message for start declaration

0x2a-42 · Dec 27, 2024 · 2db979b · 2db979b
1 parent 0ab861e
commit 2db979b
Show file tree

Hide file tree

Showing 2 changed files with 24 additions and 15 deletions.
diff --git a/src/frontend/diag.rs b/src/frontend/diag.rs
@@ -27,6 +27,7 @@ pub const REDEF_OPEN_NODE: &str = "E022";
 pub const UNDEF_CLOSE_NODE: &str = "E023";
 pub const INVALID_CLOSE_NODE: &str = "E024";
 pub const CREATE_RULE_NODE_LEFT_REC: &str = "E025";
+pub const EXPECTED_RULE: &str = "E026";
 
 pub const UNUSED_RULE: &str = "W001";
 pub const UNUSED_TOKEN: &str = "W002";
@@ -63,6 +64,7 @@ pub trait LanguageErrors {
     fn create_rule_node_left_rec(span: &Span) -> Self;
     fn unused_node_marker(span: &Span) -> Self;
     fn redundant_elision(span: &Span) -> Self;
+    fn expected_rule(span: &Span) -> Self;
 }
 
 impl LanguageErrors for Diagnostic {
@@ -341,4 +343,11 @@ impl LanguageErrors for Diagnostic {
             .with_message("node elision is redundant")
             .with_labels(vec![Label::primary((), span.clone())])
     }
+
+    fn expected_rule(span: &Span) -> Self {
+        Diagnostic::error()
+            .with_code(EXPECTED_RULE)
+            .with_message("expected rule")
+            .with_labels(vec![Label::primary((), span.clone())])
+    }
 }
diff --git a/src/frontend/sema.rs b/src/frontend/sema.rs
@@ -180,16 +180,16 @@ impl<'a> GeneralCheck<'a> {
         &mut self,
         name: &'a str,
         rule_binding: bool,
-        span: Span,
+        span: &Span,
         diags: &mut Vec<Diagnostic>,
     ) -> Option<NodeRef> {
         self.symbol_table
             .get(name)
             .or_else(|| {
                 if rule_binding {
-                    diags.push(Diagnostic::undefined_rule(&span, name));
+                    diags.push(Diagnostic::undefined_rule(span, name));
                 } else {
-                    diags.push(Diagnostic::undefined_token(&span, name));
+                    diags.push(Diagnostic::undefined_token(span, name));
                 }
                 None
             })
@@ -288,12 +288,14 @@ impl<'a> GeneralCheck<'a> {
         diags: &mut Vec<Diagnostic>,
         sema: &mut SemanticData<'a>,
     ) {
-        if let Some(rule_decl) = start_decl
-            .rule_name(cst)
-            .and_then(|(name, name_span)| self.get_symbol_binding(name, true, name_span, diags))
-            .and_then(|node| RuleDecl::cast(cst, node))
-        {
-            sema.start = Some(rule_decl);
+        if let Some((name, name_span)) = start_decl.rule_name(cst) {
+            if let Some(node) = self.get_symbol_binding(name, true, &name_span, diags) {
+                if let Some(rule_decl) = RuleDecl::cast(cst, node) {
+                    sema.start = Some(rule_decl);
+                } else {
+                    diags.push(Diagnostic::expected_rule(&name_span));
+                }
+            }
         }
     }
     fn check_right_decl(
@@ -304,7 +306,7 @@ impl<'a> GeneralCheck<'a> {
         sema: &mut SemanticData<'a>,
     ) {
         right_decl.token_names(cst, |(name, name_span)| {
-            if let Some(node) = self.get_symbol_binding(name, false, name_span.clone(), diags) {
+            if let Some(node) = self.get_symbol_binding(name, false, &name_span, diags) {
                 if let Some(token_decl) = TokenDecl::cast(cst, node) {
                     if let Some((name, _)) = token_decl.name(cst) {
                         if sema.right_associative.contains(&name) {
@@ -327,7 +329,7 @@ impl<'a> GeneralCheck<'a> {
         sema: &mut SemanticData<'a>,
     ) {
         skip_decl.token_names(cst, |(name, name_span)| {
-            if let Some(node) = self.get_symbol_binding(name, false, name_span.clone(), diags) {
+            if let Some(node) = self.get_symbol_binding(name, false, &name_span, diags) {
                 if let Some(token_decl) = TokenDecl::cast(cst, node) {
                     if sema.skipped.contains(&token_decl) {
                         diags.push(Diagnostic::redefine_as_skipped(&name_span));
@@ -398,7 +400,7 @@ impl<'a> GeneralCheck<'a> {
                 if let Some((name, name_span)) = regex.value(cst) {
                     let rule_binding = name.starts_with(|c: char| c.is_lowercase());
                     if let Some(decl) =
-                        self.get_symbol_binding(name, rule_binding, name_span.clone(), diags)
+                        self.get_symbol_binding(name, rule_binding, &name_span, diags)
                     {
                         if let Some(token) = TokenDecl::cast(cst, decl) {
                             if sema.skipped.contains(&token) {
@@ -412,9 +414,7 @@ impl<'a> GeneralCheck<'a> {
             }
             Regex::Symbol(regex) => {
                 if let Some((name, name_span)) = regex.value(cst) {
-                    if let Some(decl) =
-                        self.get_symbol_binding(name, false, name_span.clone(), diags)
-                    {
+                    if let Some(decl) = self.get_symbol_binding(name, false, &name_span, diags) {
                         if let Some(token) = TokenDecl::cast(cst, decl) {
                             if sema.skipped.contains(&token) {
                                 diags.push(Diagnostic::used_skipped(&name_span));