feat(es/parser): Make error message helpful

crates/swc_ecma_parser/src/error.rs

@@ -272,6 +272,12 @@ pub enum SyntaxError {
     TS4112,
     TSTypeAnnotationAfterAssign,
     TsNonNullAssertionNotAllowed(JsWord),
+
+    WithLabel {
+        inner: Box<Error>,
+        span: Span,
+        note: &'static str,
+    },
 }
 
 impl SyntaxError {
@@ -698,6 +704,7 @@ impl SyntaxError {
                 };
                 format!("Unexpected token. Did you mean {}?", did_you_mean).into()
             }
+            SyntaxError::WithLabel { inner, .. } => inner.error.1.msg(),
         }
     }
 }
@@ -706,23 +713,28 @@ impl Error {
     #[cold]
     #[inline(never)]
     pub fn into_diagnostic(self, handler: &Handler) -> DiagnosticBuilder {
+        if let SyntaxError::WithLabel { inner, note, span } = self.error.1 {
+            let mut db = inner.into_diagnostic(handler);
+            db.span_label(span, note);
+            return db;
+        }
+
         let span = self.span();
 
         let kind = self.into_kind();
         let msg = kind.msg();
 
-        let mut db = handler.struct_err(&msg);
-        db.set_span(span);
+        let mut db = handler.struct_span_err(span, &msg);
 
         match kind {
             SyntaxError::ExpectedSemiForExprStmt { expr } => {
-                db.span_note(
+                db.span_label(
                     expr,
                     "This is the expression part of an expression statement",
                 );
             }
             SyntaxError::MultipleDefault { previous } => {
-                db.span_note(previous, "previous default case is declared at here");
+                db.span_label(previous, "previous default case is declared at here");
             }
             _ => {}
         }

crates/swc_ecma_parser/src/parser/expr.rs

@@ -495,12 +495,7 @@ impl<I: Tokens> Parser<I> {
             })));
         }
 
-        unexpected!(
-            self,
-            "this, import, async, function, [ for array literal, { for object literal, @ for \
-             decorator, function, class, null, true, false, number, bigint, string, regexp, ` for \
-             template literal, (, or an identifier"
-        )
+        syntax_error!(self, self.input.cur_span(), SyntaxError::TS1109)
     }
 
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
@@ -751,9 +746,20 @@ impl<I: Tokens> Parser<I> {
         let start = cur_pos!(self);
 
         if eat!(self, "...") {
-            let spread = Some(span!(self, start));
+            let spread_span = span!(self, start);
+            let spread = Some(spread_span);
             self.include_in_expr(true)
                 .parse_assignment_expr()
+                .map_err(|err| {
+                    Error::new(
+                        err.span(),
+                        SyntaxError::WithLabel {
+                            inner: Box::new(err),
+                            span: spread_span,
+                            note: "An expression should follow '...'",
+                        },
+                    )
+                })
                 .map(|expr| ExprOrSpread { spread, expr })
         } else {
             self.parse_assignment_expr()
@@ -1911,7 +1917,18 @@ impl<I: Tokens> Parser<I> {
             })))
         } else {
             let has_star = eat!(self, '*');
-            let arg = self.parse_assignment_expr()?;
+            let err_span = span!(self, start);
+
+            let arg = self.parse_assignment_expr().map_err(|err| {
+                Error::new(
+                    err.span(),
+                    SyntaxError::WithLabel {
+                        inner: Box::new(err),
+                        span: err_span,
+                        note: "Tried to parse an argument of yield",
+                    },
+                )
+            })?;
 
             Ok(Box::new(Expr::Yield(YieldExpr {
                 span: span!(self, start),

crates/swc_ecma_parser/src/parser/stmt.rs

@@ -449,13 +449,27 @@ impl<'a, I: Tokens> Parser<I> {
         let start = cur_pos!(self);
 
         assert_and_bump!(self, "if");
+        let if_token = self.input.prev_span();
 
         expect!(self, '(');
         let ctx = Context {
             ignore_else_clause: false,
             ..self.ctx()
         };
-        let test = self.with_ctx(ctx).include_in_expr(true).parse_expr()?;
+        let test = self
+            .with_ctx(ctx)
+            .include_in_expr(true)
+            .parse_expr()
+            .map_err(|err| {
+                Error::new(
+                    err.span(),
+                    SyntaxError::WithLabel {
+                        inner: Box::new(err),
+                        span: if_token,
+                        note: "Tried to parse the condition for an if statement",
+                    },
+                )
+            })?;
         if !eat!(self, ')') {
             self.emit_err(self.input.cur_span(), SyntaxError::TS1005);
 

crates/swc_ecma_parser/tests/errors/async-line-break/1/input.js.stderr

@@ -1,14 +1,8 @@
 
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/errors/async-line-break/1/input.js:1:1]
- 1 | foo = async
- 2 | () => 42
-   :    ^^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/errors/async-line-break/1/input.js:1:1]
  1 | ,-> foo = async
- 2 | `-> () => 42
+ 2 | |-> () => 42
+   : `---   ^^
+   : `---- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/errors/conflict_marker_trivia_2/input.ts.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `public`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp,
-  | ` for template literal, (, or an identifier
+  x Expression expected
     ,-[$DIR/tests/errors/conflict_marker_trivia_2/input.ts:8:1]
   8 |       }
   9 | ,-> >>>>>>> A

crates/swc_ecma_parser/tests/jsx/errors/attribute-empty-expression/input.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `> (jsx tag end)`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint,
-  | string, regexp, ` for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/jsx/errors/attribute-empty-expression/input.js:1:1]
  1 | <foo bar={} />
    :              ^

crates/swc_ecma_parser/tests/jsx/errors/issue-387-5/input.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/jsx/errors/issue-387-5/input.js:1:1]
  1 | {a:1, b:2}
-   :        ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/jsx/errors/issue-387-5/input.js:1:1]
- 1 | {a:1, b:2}
-   :    ^^^^
+   :    ^^|^^
+   :      `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/03d335d8e007f61e.js.stderr

@@ -3,13 +3,6 @@
    ,-[$DIR/tests/test262-parser/fail/03d335d8e007f61e.js:1:1]
  1 | x 
  2 |  is y
-   :     ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/03d335d8e007f61e.js:1:1]
- 1 | x 
- 2 |  is y
-   :  ^^
+   :  ^| ^
+   :   `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/09af6db5fe41b857.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/09af6db5fe41b857.js:1:1]
  1 | yield v
-   :       ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/09af6db5fe41b857.js:1:1]
- 1 | yield v
-   : ^^^^^
+   : ^^|^^ ^
+   :   `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/0abefbc80bf651fa.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `;`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/0abefbc80bf651fa.js:1:1]
  1 | for (let let;;;) {}
    :               ^

crates/swc_ecma_parser/tests/test262-error-references/fail/0f512c4376a62de8.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/0f512c4376a62de8.js:1:1]
  1 | a enum;
-   :   ^^^^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/0f512c4376a62de8.js:1:1]
- 1 | a enum;
-   : ^
+   : | ^^^^
+   : `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/0ffb1c3ecf85660e.js.stderr

@@ -3,15 +3,8 @@
    ,-[$DIR/tests/test262-parser/fail/0ffb1c3ecf85660e.js:1:1]
  1 | "Hello
  2 | World"
-   :      ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/0ffb1c3ecf85660e.js:1:1]
- 1 | "Hello
- 2 | World"
-   : ^^^^^
+   : ^^|^^^
+   :   `-- This is the expression part of an expression statement
    `----
 
   x Unterminated string constant

crates/swc_ecma_parser/tests/test262-error-references/fail/17904d9a6b6ec31b.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `.`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/17904d9a6b6ec31b.js:1:1]
  1 | f(..a)
    :   ^

crates/swc_ecma_parser/tests/test262-error-references/fail/17ee4c1ca63f700d.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/17ee4c1ca63f700d.js:1:1]
  1 | 0B12
-   :    ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/17ee4c1ca63f700d.js:1:1]
- 1 | 0B12
-   : ^^^
+   : ^|^^
+   :  `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/1f7f17241661662d.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/1f7f17241661662d.js:1:1]
  1 | []=>0
-   :   ^^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/1f7f17241661662d.js:1:1]
- 1 | []=>0
-   : ^^
+   : ^|^^
+   :  `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/211656c4eaff2d9c.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `=>`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/211656c4eaff2d9c.js:1:1]
  1 | a
  2 | => 0

crates/swc_ecma_parser/tests/test262-error-references/fail/247e71c8786de6b6.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `yield`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp,
-  | ` for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/247e71c8786de6b6.js:1:1]
  1 | (function() { "use strict"; f(yield v) })
    :                               ^^^^^

crates/swc_ecma_parser/tests/test262-error-references/fail/26de1e8cdfa61321.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/26de1e8cdfa61321.js:1:1]
  1 | i + 2 = 42
-   :       ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/26de1e8cdfa61321.js:1:1]
- 1 | i + 2 = 42
-   : ^^^^^
+   : ^^|^^ ^
+   :   `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/2945f2ec8c9f3483.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/2945f2ec8c9f3483.js:1:1]
  1 | i #= 42
-   :   ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/2945f2ec8c9f3483.js:1:1]
- 1 | i #= 42
-   : ^
+   : | ^
+   : `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/2f4d2b0c0c1f960f.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/2f4d2b0c0c1f960f.js:1:1]
  1 | 0b12
-   :    ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/2f4d2b0c0c1f960f.js:1:1]
- 1 | 0b12
-   : ^^^
+   : ^|^^
+   :  `-- This is the expression part of an expression statement
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/3118eaa619345896.js.stderr

@@ -1,6 +1,5 @@
 
-  x Unexpected token `]`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/3118eaa619345896.js:1:1]
  1 | /* 
  2 | */]

crates/swc_ecma_parser/tests/test262-error-references/fail/363ecb9e2e556694.js.stderr

@@ -1,7 +1,7 @@
 
-  x Unexpected token `...`. Expected this, import, async, function, [ for array literal, { for object literal, @ for decorator, function, class, null, true, false, number, bigint, string, regexp, `
-  | for template literal, (, or an identifier
+  x Expression expected
    ,-[$DIR/tests/test262-parser/fail/363ecb9e2e556694.js:1:1]
  1 | new f(... ... g);
-   :           ^^^
+   :       ^|^ ^^^
+   :        `-- An expression should follow '...'
    `----

crates/swc_ecma_parser/tests/test262-error-references/fail/37b860dbda4d4c9c.js.stderr

@@ -2,12 +2,6 @@
   x Expected ';', '}' or <eof>
    ,-[$DIR/tests/test262-parser/fail/37b860dbda4d4c9c.js:1:1]
  1 | (function() { yield 3; })
-   :                     ^
-   `----
-
-Error: 
-  > This is the expression part of an expression statement
-   ,-[$DIR/tests/test262-parser/fail/37b860dbda4d4c9c.js:1:1]
- 1 | (function() { yield 3; })
-   :               ^^^^^
+   :               ^^|^^ ^
+   :                 `-- This is the expression part of an expression statement
    `----