feat(es/parser): Ability to get script's potential module errors (#9682)

**Description:**

In Deno I'm now parsing stuff as a program more often because I sometimes now need to discover if something is a script or es module by looking at the contents. A problem is that the module errors are discarded when parsing as a script, but I still might need them later if I discover the program the program should be treated as an ES module.

**BREAKING CHANGE:**

Adds a new method to the `Tokens` trait.

Author: dsherret

.changeset/fifty-goats-beg.md

@@ -0,0 +1,6 @@
+---
+swc_core: breaking
+swc_ecma_parser: breaking
+---
+
+feat(es/parser): Ability to get script's potential module errors

crates/swc_ecma_parser/src/lexer/state.rs

@@ -192,6 +192,10 @@ impl Tokens for Lexer<'_> {
         take(&mut self.errors.borrow_mut())
     }
 
+    fn take_script_module_errors(&mut self) -> Vec<Error> {
+        take(&mut self.module_errors.borrow_mut())
+    }
+
     fn end_pos(&self) -> BytePos {
         self.input.end_pos()
     }

crates/swc_ecma_parser/src/parser/input.rs

@@ -49,6 +49,10 @@ pub trait Tokens: Clone + Iterator<Item = TokenAndSpan> {
     fn end_pos(&self) -> BytePos;
 
     fn take_errors(&mut self) -> Vec<Error>;
+
+    /// If the program was parsed as a script, this contains the module
+    /// errors should the program be identified as a module in the future.
+    fn take_script_module_errors(&mut self) -> Vec<Error>;
 }
 
 #[derive(Clone)]
@@ -145,6 +149,10 @@ impl Tokens for TokensInput {
         take(&mut self.errors.borrow_mut())
     }
 
+    fn take_script_module_errors(&mut self) -> Vec<Error> {
+        take(&mut self.module_errors.borrow_mut())
+    }
+
     fn end_pos(&self) -> BytePos {
         self.iter
             .as_slice()
@@ -269,6 +277,10 @@ impl<I: Tokens> Tokens for Capturing<I> {
         self.inner.take_errors()
     }
 
+    fn take_script_module_errors(&mut self) -> Vec<Error> {
+        self.inner.take_script_module_errors()
+    }
+
     fn end_pos(&self) -> BytePos {
         self.inner.end_pos()
     }

crates/swc_ecma_parser/src/parser/mod.rs

@@ -90,6 +90,10 @@ impl<I: Tokens> Parser<I> {
         self.input().take_errors()
     }
 
+    pub fn take_script_module_errors(&mut self) -> Vec<Error> {
+        self.input().take_script_module_errors()
+    }
+
     pub fn parse_script(&mut self) -> PResult<Script> {
         trace_cur!(self, parse_script);
 

crates/swc_ecma_parser/src/parser/tests.rs

@@ -317,6 +317,7 @@ fn illegal_language_mode_directive1() {
         },
     );
 }
+
 #[test]
 fn illegal_language_mode_directive2() {
     test_parser(
@@ -346,3 +347,25 @@ fn illegal_language_mode_directive2() {
 fn parse_non_strict_for_loop() {
     script("for (var v1 = 1 in v3) {}");
 }
+
+#[test]
+fn parse_program_take_script_module_errors() {
+    test_parser(r#"077;"#, Default::default(), |p| {
+        let program = p.parse_program()?;
+
+        assert_eq!(p.take_errors(), vec![]);
+        // will contain the script's potential module errors
+        assert_eq!(
+            p.take_script_module_errors(),
+            vec![Error::new(
+                Span {
+                    lo: BytePos(1),
+                    hi: BytePos(4),
+                },
+                crate::parser::SyntaxError::LegacyOctal
+            )]
+        );
+
+        Ok(program)
+    });
+}