fix(traverse): invalid variable name generated by generate_uid_based_on_node (#5407)

close: #5371

crates/oxc_traverse/src/context/identifier.rs

@@ -0,0 +1,58 @@
+use std::borrow::Cow;
+
+use oxc_syntax::identifier::{is_identifier_name, is_identifier_part, is_identifier_start};
+
+/// Convert a str to a valid identifier name.
+///
+/// Based on Babel's [`toIdentifier`](https://github.com/babel/babel/blob/3bcfee232506a4cebe410f02042fb0f0adeeb0b1/packages/babel-types/src/converters/toIdentifier.ts#L4-L26) function.
+pub fn to_identifier(input: &str) -> Cow<str> {
+    if is_identifier_name(input) {
+        return Cow::Borrowed(input);
+    }
+
+    let mut name = String::with_capacity(input.len());
+
+    let mut capitalize_next = false;
+
+    let mut chars = input.chars();
+    if let Some(first) = chars.next() {
+        if is_identifier_start(first) {
+            name.push(first);
+        } else {
+            capitalize_next = true;
+        }
+    }
+
+    for c in chars {
+        if !is_identifier_part(c) {
+            capitalize_next = true;
+        } else if capitalize_next {
+            name.push(c.to_ascii_uppercase());
+            capitalize_next = false;
+        } else {
+            name.push(c);
+        }
+    }
+
+    if name.is_empty() {
+        return Cow::Borrowed("_");
+    }
+
+    Cow::Owned(name)
+}
+
+#[test]
+fn test() {
+    assert_eq!(to_identifier("foo"), "foo");
+    assert_eq!(to_identifier("fooBar"), "fooBar");
+    assert_eq!(to_identifier("fooBar1"), "fooBar1");
+
+    assert_eq!(to_identifier("foo-bar"), "fooBar");
+    assert_eq!(to_identifier("foo bar"), "fooBar");
+    assert_eq!(to_identifier("foo-bar-1"), "fooBar1");
+    assert_eq!(to_identifier("1foo-bar"), "FooBar");
+    assert_eq!(to_identifier("1-foo-bar"), "FooBar");
+    assert_eq!(to_identifier("-- --"), "_");
+
+    assert_eq!(to_identifier("_output$headers$x-amzn-requestid"), "_output$headers$xAmznRequestid");
+}

crates/oxc_traverse/src/context/mod.rs

@@ -16,6 +16,7 @@ mod ancestry;
 mod ast_operations;
 use ancestry::PopToken;
 pub use ancestry::TraverseAncestry;
+mod identifier;
 mod scoping;
 pub use scoping::TraverseScoping;
 

crates/oxc_traverse/src/context/scoping.rs

@@ -11,7 +11,7 @@ use oxc_syntax::{
     symbol::{SymbolFlags, SymbolId},
 };
 
-use super::ast_operations::GatherNodeParts;
+use super::{ast_operations::GatherNodeParts, identifier::to_identifier};
 use crate::scopes_collector::ChildScopeCollector;
 
 /// Traverse scope context.
@@ -248,7 +248,7 @@ impl TraverseScoping {
             parts.push_str(part);
         });
         let name = if parts.is_empty() { "ref" } else { parts.trim_start_matches('_') };
-        self.generate_uid(name, scope_id, flags)
+        self.generate_uid(&to_identifier(name.get(..20).unwrap_or(name)), scope_id, flags)
     }
 
     /// Generate UID in current scope based on node.

tasks/transform_conformance/oxc.snap.md

@@ -1,13 +1,19 @@
 commit: 3bcfee23
 
-Passed: 11/40
+Passed: 11/41
 
 # All Passed:
 * babel-plugin-transform-optional-catch-binding
 * babel-preset-typescript
 
 
-# babel-plugin-transform-nullish-coalescing-operator (0/1)
+# babel-plugin-transform-nullish-coalescing-operator (0/2)
+* invalid-variable-name/input.js
+  x Reference flags mismatch:
+  | after transform: ReferenceId(3): ReferenceFlags(Write)
+  | rebuilt        : ReferenceId(0): ReferenceFlags(Read | Write)
+
+
 * transform-in-arrow-function-expression/input.js
   x Reference flags mismatch:
   | after transform: ReferenceId(3): ReferenceFlags(Write)

tasks/transform_conformance/tests/babel-plugin-transform-nullish-coalescing-operator/test/fixtures/invalid-variable-name/input.js

@@ -0,0 +1 @@
+out.head["foo-bar-qux"] ?? out.head["moon-unit"]

tasks/transform_conformance/tests/babel-plugin-transform-nullish-coalescing-operator/test/fixtures/invalid-variable-name/output.js

@@ -0,0 +1,2 @@
+var _out$head$fooBarQux;
+(_out$head$fooBarQux = out.head["foo-bar-qux"]) !== null && _out$head$fooBarQux !== void 0 ? _out$head$fooBarQux : out.head["moon-unit"];