internal: Compute syntax validation errors on demand

crates/syntax/src/lib.rs

@@ -97,8 +97,11 @@ impl<T> Parse<T> {
     pub fn syntax_node(&self) -> SyntaxNode {
         SyntaxNode::new_root(self.green.clone())
     }
-    pub fn errors(&self) -> &[SyntaxError] {
-        self.errors.as_deref().unwrap_or_default()
+
+    pub fn errors(&self) -> Vec<SyntaxError> {
+        let mut errors = if let Some(e) = self.errors.as_deref() { e.to_vec() } else { vec![] };
+        validation::validate(&self.syntax_node(), &mut errors);
+        errors
     }
 }
 
@@ -111,10 +114,10 @@ impl<T: AstNode> Parse<T> {
         T::cast(self.syntax_node()).unwrap()
     }
 
-    pub fn ok(self) -> Result<T, Arc<[SyntaxError]>> {
-        match self.errors {
-            Some(e) => Err(e),
-            None => Ok(self.tree()),
+    pub fn ok(self) -> Result<T, Vec<SyntaxError>> {
+        match self.errors() {
+            errors if !errors.is_empty() => Err(errors),
+            _ => Ok(self.tree()),
         }
     }
 }
@@ -132,7 +135,7 @@ impl Parse<SyntaxNode> {
 impl Parse<SourceFile> {
     pub fn debug_dump(&self) -> String {
         let mut buf = format!("{:#?}", self.tree().syntax());
-        for err in self.errors.as_deref().into_iter().flat_map(<[_]>::iter) {
+        for err in self.errors() {
             format_to!(buf, "error {:?}: {}\n", err.range(), err);
         }
         buf
@@ -169,11 +172,9 @@ pub use crate::ast::SourceFile;
 impl SourceFile {
     pub fn parse(text: &str) -> Parse<SourceFile> {
         let _p = tracing::span!(tracing::Level::INFO, "SourceFile::parse").entered();
-        let (green, mut errors) = parsing::parse_text(text);
+        let (green, errors) = parsing::parse_text(text);
         let root = SyntaxNode::new_root(green.clone());
 
-        errors.extend(validation::validate(&root));
-
         assert_eq!(root.kind(), SyntaxKind::SOURCE_FILE);
         Parse {
             green,

crates/syntax/src/tests.rs

@@ -39,7 +39,7 @@ fn benchmark_parser() {
     let tree = {
         let _b = bench("parsing");
         let p = SourceFile::parse(&data);
-        assert!(p.errors.is_none());
+        assert!(p.errors().is_empty());
         assert_eq!(p.tree().syntax.text_range().len(), 352474.into());
         p.tree()
     };
@@ -57,7 +57,7 @@ fn validation_tests() {
     dir_tests(&test_data_dir(), &["parser/validation"], "rast", |text, path| {
         let parse = SourceFile::parse(text);
         let errors = parse.errors();
-        assert_errors_are_present(errors, path);
+        assert_errors_are_present(&errors, path);
         parse.debug_dump()
     });
 }

crates/syntax/src/validation.rs

@@ -15,34 +15,32 @@ use crate::{
     SyntaxNode, SyntaxToken, TextSize, T,
 };
 
-pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
+pub(crate) fn validate(root: &SyntaxNode, errors: &mut Vec<SyntaxError>) {
     let _p = tracing::span!(tracing::Level::INFO, "parser::validate").entered();
     // FIXME:
     // * Add unescape validation of raw string literals and raw byte string literals
     // * Add validation of doc comments are being attached to nodes
 
-    let mut errors = Vec::new();
     for node in root.descendants() {
         match_ast! {
             match node {
-                ast::Literal(it) => validate_literal(it, &mut errors),
-                ast::Const(it) => validate_const(it, &mut errors),
-                ast::BlockExpr(it) => block::validate_block_expr(it, &mut errors),
-                ast::FieldExpr(it) => validate_numeric_name(it.name_ref(), &mut errors),
-                ast::RecordExprField(it) => validate_numeric_name(it.name_ref(), &mut errors),
-                ast::Visibility(it) => validate_visibility(it, &mut errors),
-                ast::RangeExpr(it) => validate_range_expr(it, &mut errors),
-                ast::PathSegment(it) => validate_path_keywords(it, &mut errors),
-                ast::RefType(it) => validate_trait_object_ref_ty(it, &mut errors),
-                ast::PtrType(it) => validate_trait_object_ptr_ty(it, &mut errors),
-                ast::FnPtrType(it) => validate_trait_object_fn_ptr_ret_ty(it, &mut errors),
-                ast::MacroRules(it) => validate_macro_rules(it, &mut errors),
-                ast::LetExpr(it) => validate_let_expr(it, &mut errors),
+                ast::Literal(it) => validate_literal(it, errors),
+                ast::Const(it) => validate_const(it, errors),
+                ast::BlockExpr(it) => block::validate_block_expr(it, errors),
+                ast::FieldExpr(it) => validate_numeric_name(it.name_ref(), errors),
+                ast::RecordExprField(it) => validate_numeric_name(it.name_ref(), errors),
+                ast::Visibility(it) => validate_visibility(it, errors),
+                ast::RangeExpr(it) => validate_range_expr(it, errors),
+                ast::PathSegment(it) => validate_path_keywords(it, errors),
+                ast::RefType(it) => validate_trait_object_ref_ty(it, errors),
+                ast::PtrType(it) => validate_trait_object_ptr_ty(it, errors),
+                ast::FnPtrType(it) => validate_trait_object_fn_ptr_ret_ty(it, errors),
+                ast::MacroRules(it) => validate_macro_rules(it, errors),
+                ast::LetExpr(it) => validate_let_expr(it, errors),
                 _ => (),
             }
         }
     }
-    errors
 }
 
 fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> (&'static str, bool) {