Fix an unintended behavior with const-fn

crates/erg_compiler/context/eval.rs

@@ -133,6 +133,8 @@ impl Context {
             Accessor::Ident(ident) => {
                 if let Some(val) = self.rec_get_const_obj(ident.inspect()) {
                     Ok(val.clone())
+                } else if self.kind.is_subr() {
+                    feature_error!(self, ident.loc(), "const parameters")
                 } else if ident.is_const() {
                     Err(EvalErrors::from(EvalError::no_var_error(
                         self.cfg.input.clone(),

crates/erg_compiler/context/initialize/mod.rs

@@ -14,7 +14,6 @@ use std::path::PathBuf;
 
 use erg_common::config::ErgConfig;
 use erg_common::dict;
-use erg_common::env::erg_pystd_path;
 use erg_common::error::Location;
 use erg_common::fresh::fresh_varname;
 #[allow(unused_imports)]
@@ -414,7 +413,7 @@ const KW_SUPER: &str = "Super";
 
 #[cfg(not(feature = "no_std"))]
 pub fn builtins_path() -> PathBuf {
-    erg_pystd_path().join("builtins.d.er")
+    erg_common::env::erg_pystd_path().join("builtins.d.er")
 }
 #[cfg(feature = "no_std")]
 pub fn builtins_path() -> PathBuf {

crates/erg_compiler/context/mod.rs

@@ -211,15 +211,19 @@ impl ContextKind {
         matches!(self, Self::Class | Self::Trait | Self::StructuralTrait)
     }
 
-    pub fn is_class(&self) -> bool {
+    pub const fn is_subr(&self) -> bool {
+        matches!(self, Self::Func | Self::Proc)
+    }
+
+    pub const fn is_class(&self) -> bool {
         matches!(self, Self::Class)
     }
 
-    pub fn is_trait(&self) -> bool {
+    pub const fn is_trait(&self) -> bool {
         matches!(self, Self::Trait | Self::StructuralTrait)
     }
 
-    pub fn is_patch(&self) -> bool {
+    pub const fn is_patch(&self) -> bool {
         matches!(self, Self::Patch(_) | Self::GluePatch(_))
     }
 }

crates/erg_compiler/context/register.rs

@@ -12,7 +12,7 @@ use erg_common::set::Set;
 use erg_common::traits::{Locational, Stream};
 use erg_common::vis::Visibility;
 use erg_common::{enum_unwrap, get_hash, log, set};
-use erg_common::{fn_name, Str};
+use erg_common::Str;
 
 use ast::{Decorator, DefId, Identifier, OperationKind, SimpleTypeSpec, VarName};
 use erg_parser::ast::{self, ConstIdentifier};
@@ -599,14 +599,12 @@ impl Context {
     ) -> TyCheckResult<()> {
         // already defined as const
         if ident.is_const() {
-            let Some(vi) = self.decls.remove(ident.inspect()) else {
-                return Err(TyCheckErrors::from(TyCheckError::unreachable(
-                    self.cfg.input.clone(),
-                    fn_name!(),
-                    line!(),
-                )));
-            };
-            self.locals.insert(ident.name.clone(), vi);
+            if let Some(vi) = self.decls.remove(ident.inspect()) {
+                self.locals.insert(ident.name.clone(), vi);
+            } else {
+                log!(err "not found: {}", ident.name);
+                return Ok(());
+            }
         }
         let muty = if ident.is_const() {
             Mutability::Const