Add keep_shadowed_builtins feature to roc_parse

compiler/parse/Cargo.toml

@@ -5,6 +5,11 @@ authors = ["The Roc Contributors"]
 license = "UPL-1.0"
 edition = "2018"
 
+[features]
+# If enabled, parser accepts `Dict.#hashTestOnly` etc.
+# For development puporpse.
+keep_shadowed_builtins = []
+
 [dependencies]
 roc_collections = { path = "../collections" }
 roc_region = { path = "../region" }

compiler/parse/src/ident.rs

@@ -220,6 +220,10 @@ pub enum BadIdent {
     BadPrivateTag(Row, Col),
 }
 
+fn chomp_lowercase_part_keep_shadowed_builtins(buffer: &[u8]) -> Result<&str, Progress> {
+    chomp_part(|c: char| c.is_lowercase() || c == '#', buffer)
+}
+
 fn chomp_lowercase_part(buffer: &[u8]) -> Result<&str, Progress> {
     chomp_part(|c: char| c.is_lowercase(), buffer)
 }
@@ -499,7 +503,12 @@ fn chomp_access_chain<'a>(buffer: &'a [u8], parts: &mut Vec<'a, &'a str>) -> Res
 
     while let Some(b'.') = buffer.get(chomped) {
         match &buffer.get(chomped + 1..) {
-            Some(slice) => match chomp_lowercase_part(slice) {
+            Some(slice) => {
+                let res = match cfg!(feature = "keep_shadowed_builtins") {
+                    true => chomp_lowercase_part_keep_shadowed_builtins(slice),
+                    false => chomp_lowercase_part(slice),
+                };
+                match res {
                     Ok(name) => {
                         let value = unsafe {
                             std::str::from_utf8_unchecked(
@@ -507,11 +516,11 @@ fn chomp_access_chain<'a>(buffer: &'a [u8], parts: &mut Vec<'a, &'a str>) -> Res
                             )
                         };
                         parts.push(value);
-
                         chomped += name.len() + 1;
                     }
                     Err(_) => return Err(chomped as u16 + 1),
-            },
+                }
+            }
             None => return Err(chomped as u16 + 1),
         }
     }