chore: improve error for patterns (#2004)

* improve error for patterns * fix error message * Update crates/noirc_frontend/src/parser/parser.rs * Update crates/noirc_frontend/src/parser/errors.rs * Update crates/noirc_frontend/src/parser/errors.rs --------- Co-authored-by: jfecher <[email protected]>
noir-lang · Jul 26, 2023 · 453e477 · 453e477
1 parent be44c7b
commit 453e477
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Showing 2 changed files with 23 additions and 1 deletion.
diff --git a/crates/noirc_frontend/src/parser/errors.rs b/crates/noirc_frontend/src/parser/errors.rs
@@ -13,6 +13,8 @@ use super::labels::ParsingRuleLabel;
 pub enum ParserErrorReason {
     #[error("Unexpected '{0}', expected a field name")]
     ExpectedFieldName(Token),
+    #[error("expected a pattern but found a type - {0}")]
+    ExpectedPatternButFoundType(Token),
     #[error("Expected a ; separating these two statements")]
     MissingSeparatingSemi,
     #[error("constrain keyword is deprecated")]
@@ -70,6 +72,14 @@ impl ParserError {
         error.reason = Some(reason);
         error
     }
+
+    pub fn found(&self) -> &Token {
+        &self.found
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
 }
 
 impl std::fmt::Display for ParserError {
@@ -107,6 +117,9 @@ impl From<ParserError> for Diagnostic {
                         "The 'constrain' keyword has been deprecated. Please use the 'assert' function instead.".into(),
                         error.span,
                     ),
+                    reason @ ParserErrorReason::ExpectedPatternButFoundType(ty) => {
+                        Diagnostic::simple_error(reason.to_string(), format!("{ty} is a type and cannot be used as a variable name"), error.span)
+                    }
                     other => {
 
                         Diagnostic::simple_error(format!("{other}"), String::new(), error.span)

diff --git a/crates/noirc_frontend/src/parser/parser.rs b/crates/noirc_frontend/src/parser/parser.rs
@@ -683,7 +683,16 @@ where
 
 fn pattern() -> impl NoirParser<Pattern> {
     recursive(|pattern| {
-        let ident_pattern = ident().map(Pattern::Identifier);
+        let ident_pattern = ident().map(Pattern::Identifier).map_err(|mut error| {
+            if matches!(error.found(), Token::IntType(..)) {
+                error = ParserError::with_reason(
+                    ParserErrorReason::ExpectedPatternButFoundType(error.found().clone()),
+                    error.span(),
+                );
+            }
+
+            error
+        });
 
         let mut_pattern = keyword(Keyword::Mut)
             .ignore_then(pattern.clone())