Improve error message for referring to a variable before its definition

compiler/erg_compiler/context/eval.rs

@@ -13,6 +13,8 @@ use erg_common::{dict, fn_name, option_enum_unwrap, set};
 use erg_common::{RcArray, Str};
 use OpKind::*;
 
+use erg_parser::ast::Dict as AstDict;
+use erg_parser::ast::Set as AstSet;
 use erg_parser::ast::*;
 use erg_parser::token::{Token, TokenKind};
 
@@ -227,10 +229,21 @@ impl Context {
                     let args = self.eval_args(&call.args)?;
                     self.call(subr, args, call.loc())
                 }
-                Accessor::Attr(_attr) => todo!(),
-                Accessor::TupleAttr(_attr) => todo!(),
-                Accessor::Subscr(_subscr) => todo!(),
-                Accessor::TypeApp(_type_app) => todo!(),
+                // TODO: eval attr
+                Accessor::Attr(_attr) => Err(EvalErrors::from(EvalError::not_const_expr(
+                    self.cfg.input.clone(),
+                    line!() as usize,
+                    call.loc(),
+                    self.caused_by(),
+                ))),
+                // TODO: eval type app
+                Accessor::TypeApp(_type_app) => Err(EvalErrors::from(EvalError::not_const_expr(
+                    self.cfg.input.clone(),
+                    line!() as usize,
+                    call.loc(),
+                    self.caused_by(),
+                ))),
+                _ => unreachable!(),
             }
         } else {
             todo!()
@@ -306,6 +319,52 @@ impl Context {
         Ok(ValueObj::Array(RcArray::from(elems)))
     }
 
+    fn eval_const_set(&self, set: &AstSet) -> EvalResult<ValueObj> {
+        let mut elems = vec![];
+        match set {
+            AstSet::Normal(arr) => {
+                for elem in arr.elems.pos_args().iter() {
+                    let elem = self.eval_const_expr(&elem.expr)?;
+                    elems.push(elem);
+                }
+            }
+            _ => {
+                todo!()
+            }
+        }
+        Ok(ValueObj::Set(Set::from(elems)))
+    }
+
+    fn eval_const_dict(&self, dict: &AstDict) -> EvalResult<ValueObj> {
+        let mut elems = dict! {};
+        match dict {
+            AstDict::Normal(dic) => {
+                for elem in dic.kvs.iter() {
+                    let key = self.eval_const_expr(&elem.key)?;
+                    let value = self.eval_const_expr(&elem.value)?;
+                    elems.insert(key, value);
+                }
+            }
+            _ => {
+                todo!()
+            }
+        }
+        Ok(ValueObj::Dict(elems))
+    }
+
+    fn eval_const_tuple(&self, tuple: &Tuple) -> EvalResult<ValueObj> {
+        let mut elems = vec![];
+        match tuple {
+            Tuple::Normal(arr) => {
+                for elem in arr.elems.pos_args().iter() {
+                    let elem = self.eval_const_expr(&elem.expr)?;
+                    elems.push(elem);
+                }
+            }
+        }
+        Ok(ValueObj::Tuple(RcArray::from(elems)))
+    }
+
     fn eval_const_record(&self, record: &Record) -> EvalResult<ValueObj> {
         match record {
             Record::Normal(rec) => self.eval_const_normal_record(rec),
@@ -456,9 +515,17 @@ impl Context {
             Expr::Call(call) => self.eval_const_call(call),
             Expr::Def(def) => self.eval_const_def(def),
             Expr::Array(arr) => self.eval_const_array(arr),
+            Expr::Set(set) => self.eval_const_set(set),
+            Expr::Dict(dict) => self.eval_const_dict(dict),
+            Expr::Tuple(tuple) => self.eval_const_tuple(tuple),
             Expr::Record(rec) => self.eval_const_record(rec),
             Expr::Lambda(lambda) => self.eval_const_lambda(lambda),
-            other => todo!("{other}"),
+            other => Err(EvalErrors::from(EvalError::not_const_expr(
+                self.cfg.input.clone(),
+                line!() as usize,
+                other.loc(),
+                self.caused_by(),
+            ))),
         }
     }
 

compiler/erg_compiler/context/inquire.rs

@@ -351,19 +351,34 @@ impl Context {
                     }
                 }
             }
+        } else if let Some((name, _vi)) = self
+            .future_defined_locals
+            .get_key_value(&ident.inspect()[..])
+        {
+            return Err(TyCheckError::access_before_def_error(
+                input.clone(),
+                line!() as usize,
+                ident.loc(),
+                namespace.into(),
+                ident.inspect(),
+                name.ln_begin().unwrap(),
+                self.get_similar_name(ident.inspect()),
+            ));
         }
         if let Some(parent) = self.get_outer().or_else(|| self.get_builtins()) {
-            if let Ok(vi) = parent.rec_get_var_info(ident, acc_kind, input, namespace) {
-                Ok(vi)
-            } else {
-                Err(TyCheckError::no_var_error(
-                    input.clone(),
-                    line!() as usize,
-                    ident.loc(),
-                    namespace.into(),
-                    ident.inspect(),
-                    self.get_similar_name(ident.inspect()),
-                ))
+            match parent.rec_get_var_info(ident, acc_kind, input, namespace) {
+                Ok(vi) => Ok(vi),
+                Err(err) if err.core.kind == ErrorKind::DummyError => {
+                    Err(TyCheckError::no_var_error(
+                        input.clone(),
+                        line!() as usize,
+                        ident.loc(),
+                        namespace.into(),
+                        ident.inspect(),
+                        self.get_similar_name(ident.inspect()),
+                    ))
+                }
+                Err(err) => Err(err),
             }
         } else {
             Err(TyCheckError::dummy(

compiler/erg_compiler/context/mod.rs

@@ -346,6 +346,8 @@ pub struct Context {
     pub(crate) trait_impls: Dict<Str, Set<TypeRelationInstance>>,
     /// stores declared names (not initialized)
     pub(crate) decls: Dict<VarName, VarInfo>,
+    /// for error reporting
+    pub(crate) future_defined_locals: Dict<VarName, VarInfo>,
     // stores defined names
     // 型の一致はHashMapでは判定できないため、keyはVarNameとして1つずつ見ていく
     /// ```python
@@ -537,6 +539,7 @@ impl Context {
             trait_impls: Dict::default(),
             params: params_,
             decls: Dict::default(),
+            future_defined_locals: Dict::default(),
             locals: Dict::with_capacity(capacity),
             consts: Dict::default(),
             mono_types: Dict::default(),

compiler/erg_compiler/context/register.rs

@@ -37,6 +37,8 @@ use Visibility::*;
 
 use super::instantiate::TyVarCache;
 
+const UBAR: &Str = &Str::ever("_");
+
 impl Context {
     /// If it is a constant that is defined, there must be no variable of the same name defined across all scopes
     pub(crate) fn registered_info(
@@ -62,35 +64,37 @@ impl Context {
         }
     }
 
-    fn _declare_var(
+    fn pre_define_var(
         &mut self,
         sig: &ast::VarSignature,
         opt_t: Option<Type>,
         id: Option<DefId>,
     ) -> TyCheckResult<()> {
-        let muty = Mutability::from(&sig.inspect().unwrap()[..]);
-        match &sig.pat {
-            ast::VarPattern::Ident(ident) => {
-                let vis = ident.vis();
-                let kind = id.map_or(VarKind::Declared, VarKind::Defined);
-                let sig_t = self.instantiate_var_sig_t(sig.t_spec.as_ref(), opt_t, PreRegister)?;
-                if let Some(_decl) = self.decls.remove(&ident.name) {
-                    Err(TyCheckErrors::from(TyCheckError::duplicate_decl_error(
-                        self.cfg.input.clone(),
-                        line!() as usize,
-                        sig.loc(),
-                        self.caused_by(),
-                        ident.name.inspect(),
-                    )))
-                } else {
-                    self.decls.insert(
-                        ident.name.clone(),
-                        VarInfo::new(sig_t, muty, vis, kind, None, self.impl_of(), None),
-                    );
-                    Ok(())
-                }
+        let muty = Mutability::from(&sig.inspect().unwrap_or(UBAR)[..]);
+        let ident = match &sig.pat {
+            ast::VarPattern::Ident(ident) => ident,
+            ast::VarPattern::Discard(_) => {
+                return Ok(());
             }
             _ => todo!(),
+        };
+        let vis = ident.vis();
+        let kind = id.map_or(VarKind::Declared, VarKind::Defined);
+        let sig_t = self.instantiate_var_sig_t(sig.t_spec.as_ref(), opt_t, PreRegister)?;
+        if let Some(_decl) = self.decls.remove(&ident.name) {
+            Err(TyCheckErrors::from(TyCheckError::duplicate_decl_error(
+                self.cfg.input.clone(),
+                line!() as usize,
+                sig.loc(),
+                self.caused_by(),
+                ident.name.inspect(),
+            )))
+        } else {
+            self.future_defined_locals.insert(
+                ident.name.clone(),
+                VarInfo::new(sig_t, muty, vis, kind, None, self.impl_of(), None),
+            );
+            Ok(())
         }
     }
 
@@ -555,8 +559,7 @@ impl Context {
 
     pub(crate) fn preregister_def(&mut self, def: &ast::Def) -> TyCheckResult<()> {
         let id = Some(def.body.id);
-        let ubar = Str::ever("_");
-        let __name__ = def.sig.ident().map(|i| i.inspect()).unwrap_or(&ubar);
+        let __name__ = def.sig.ident().map(|i| i.inspect()).unwrap_or(UBAR);
         match &def.sig {
             ast::Signature::Subr(sig) => {
                 if sig.is_const() {
@@ -587,32 +590,39 @@ impl Context {
                     self.declare_sub(sig, id)?;
                 }
             }
-            ast::Signature::Var(sig) if sig.is_const() => {
-                let kind = ContextKind::from(def.def_kind());
-                self.grow(__name__, kind, sig.vis(), None);
-                let (obj, const_t) = match self.eval_const_block(&def.body.block) {
-                    Ok(obj) => (obj.clone(), v_enum(set! {obj})),
-                    Err(e) => {
-                        return Err(e);
+            ast::Signature::Var(sig) => {
+                if sig.is_const() {
+                    let kind = ContextKind::from(def.def_kind());
+                    self.grow(__name__, kind, sig.vis(), None);
+                    let (obj, const_t) = match self.eval_const_block(&def.body.block) {
+                        Ok(obj) => (obj.clone(), v_enum(set! {obj})),
+                        Err(e) => {
+                            return Err(e);
+                        }
+                    };
+                    if let Some(spec) = sig.t_spec.as_ref() {
+                        let mut dummy_tv_cache = TyVarCache::new(self.level, self);
+                        let spec_t = self.instantiate_typespec(
+                            spec,
+                            None,
+                            &mut dummy_tv_cache,
+                            PreRegister,
+                            false,
+                        )?;
+                        self.sub_unify(&const_t, &spec_t, def.body.loc(), None)?;
                     }
-                };
-                if let Some(spec) = sig.t_spec.as_ref() {
-                    let mut dummy_tv_cache = TyVarCache::new(self.level, self);
-                    let spec_t = self.instantiate_typespec(
-                        spec,
-                        None,
-                        &mut dummy_tv_cache,
-                        PreRegister,
-                        false,
-                    )?;
-                    self.sub_unify(&const_t, &spec_t, def.body.loc(), None)?;
-                }
-                self.pop();
-                if let Some(ident) = sig.ident() {
-                    self.register_gen_const(ident, obj)?;
+                    self.pop();
+                    if let Some(ident) = sig.ident() {
+                        self.register_gen_const(ident, obj)?;
+                    }
+                } else {
+                    let opt_t = self
+                        .eval_const_block(&def.body.block)
+                        .map(|o| v_enum(set! {o}))
+                        .ok();
+                    self.pre_define_var(sig, opt_t, id)?;
                 }
             }
-            _ => {}
         }
         Ok(())
     }

compiler/erg_compiler/error.rs

@@ -1577,6 +1577,44 @@ impl LowerError {
         )
     }
 
+    pub fn access_before_def_error(
+        input: Input,
+        errno: usize,
+        loc: Location,
+        caused_by: String,
+        name: &str,
+        defined_line: usize,
+        similar_name: Option<&str>,
+    ) -> Self {
+        let name = readable_name(name);
+        let hint = similar_name.map(|n| {
+            let n = StyledStr::new(n, Some(HINT), Some(ATTR));
+            switch_lang!(
+                "japanese" => format!("似た名前の変数があります: {n}"),
+                "simplified_chinese" => format!("存在相同名称变量: {n}"),
+                "traditional_chinese" => format!("存在相同名稱變量: {n}"),
+                "english" => format!("exists a similar name variable: {n}"),
+            )
+        });
+        let found = StyledString::new(name, Some(ERR), Some(ATTR));
+        Self::new(
+            ErrorCore::new(
+                vec![SubMessage::ambiguous_new(loc, vec![], hint)],
+                switch_lang!(
+                    "japanese" => format!("定義({defined_line}行目)より前で{found}を参照することは出来ません"),
+                    "simplified_chinese" => format!("在{found}定义({defined_line}行)之前引用是不允许的"),
+                    "traditional_chinese" => format!("在{found}定義({defined_line}行)之前引用是不允許的"),
+                    "english" => format!("cannot reference {found} before its definition (line {defined_line})"),
+                ),
+                errno,
+                NameError,
+                loc,
+            ),
+            input,
+            caused_by,
+        )
+    }
+
     pub fn no_type_error(
         input: Input,
         errno: usize,

compiler/erg_compiler/ty/value.rs

@@ -20,7 +20,7 @@ use erg_common::{dict, fmt_iter, impl_display_from_debug, switch_lang};
 use erg_common::{RcArray, Str};
 
 use super::codeobj::CodeObj;
-use super::constructors::{array_t, mono, poly, refinement, set_t, tuple_t};
+use super::constructors::{array_t, dict_t, mono, poly, refinement, set_t, tuple_t};
 use super::free::fresh_varname;
 use super::typaram::TyParam;
 use super::{ConstSubr, HasType, Predicate, Type};
@@ -743,7 +743,12 @@ impl ValueObj {
                 arr.iter().next().unwrap().class(),
                 TyParam::value(arr.len()),
             ),
-            Self::Dict(_dict) => todo!(),
+            Self::Dict(dict) => {
+                let tp = dict
+                    .iter()
+                    .map(|(k, v)| (TyParam::value(k.clone()), TyParam::value(v.clone())));
+                dict_t(TyParam::Dict(tp.collect()))
+            }
             Self::Tuple(tup) => tuple_t(tup.iter().map(|v| v.class()).collect()),
             Self::Set(st) => set_t(st.iter().next().unwrap().class(), TyParam::value(st.len())),
             Self::Code(_) => Type::Code,
@@ -771,7 +776,13 @@ impl ValueObj {
                 Self::Array(arr) => poly(
                     "Array!",
                     vec![
-                        TyParam::t(arr.iter().next().unwrap().class()),
+                        // REVIEW: Never?
+                        TyParam::t(
+                            arr.iter()
+                                .next()
+                                .map(|elem| elem.class())
+                                .unwrap_or(Type::Never),
+                        ),
                         TyParam::value(arr.len()).mutate(),
                     ],
                 ),