core: improve binop and cmpop error messages

nac3core/src/codegen/expr.rs

@@ -27,7 +27,7 @@ use crate::{
         DefinitionId, TopLevelDef,
     },
     typecheck::{
-        magic_methods::{binop_assign_name, binop_name, unaryop_name},
+        magic_methods::{Binop, BinopVariant, HasOpInfo},
         typedef::{FunSignature, FuncArg, Type, TypeEnum, TypeVarId, Unifier, VarMap},
     },
 };
@@ -1165,10 +1165,9 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
     left: (&Option<Type>, BasicValueEnum<'ctx>),
-    op: Operator,
+    op: Binop,
     right: (&Option<Type>, BasicValueEnum<'ctx>),
     loc: Location,
-    is_aug_assign: bool,
 ) -> Result<Option<ValueEnum<'ctx>>, String> {
     let (left_ty, left_val) = left;
     let (right_ty, right_val) = right;
@@ -1180,17 +1179,17 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
     // which would be unchanged until further unification, which we would never do
     // when doing code generation for function instances
     if ty1 == ty2 && [ctx.primitives.int32, ctx.primitives.int64].contains(&ty1) {
-        Ok(Some(ctx.gen_int_ops(generator, op, left_val, right_val, true).into()))
+        Ok(Some(ctx.gen_int_ops(generator, op.base, left_val, right_val, true).into()))
     } else if ty1 == ty2 && [ctx.primitives.uint32, ctx.primitives.uint64].contains(&ty1) {
-        Ok(Some(ctx.gen_int_ops(generator, op, left_val, right_val, false).into()))
-    } else if [Operator::LShift, Operator::RShift].contains(&op) {
+        Ok(Some(ctx.gen_int_ops(generator, op.base, left_val, right_val, false).into()))
+    } else if [Operator::LShift, Operator::RShift].contains(&op.base) {
         let signed = [ctx.primitives.int32, ctx.primitives.int64].contains(&ty1);
-        Ok(Some(ctx.gen_int_ops(generator, op, left_val, right_val, signed).into()))
+        Ok(Some(ctx.gen_int_ops(generator, op.base, left_val, right_val, signed).into()))
     } else if ty1 == ty2 && ctx.primitives.float == ty1 {
-        Ok(Some(ctx.gen_float_ops(op, left_val, right_val).into()))
+        Ok(Some(ctx.gen_float_ops(op.base, left_val, right_val).into()))
     } else if ty1 == ctx.primitives.float && ty2 == ctx.primitives.int32 {
         // Pow is the only operator that would pass typecheck between float and int
-        assert_eq!(op, Operator::Pow);
+        assert_eq!(op.base, Operator::Pow);
         let res = call_float_powi(
             ctx,
             left_val.into_float_value(),
@@ -1203,11 +1202,11 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
     {
         let llvm_usize = generator.get_size_type(ctx.ctx);
 
-        if is_aug_assign {
+        if op.variant == BinopVariant::AugAssign {
             todo!("Augmented assignment operators not implemented for lists")
         }
 
-        match op {
+        match op.base {
             Operator::Add => {
                 debug_assert_eq!(ty1.obj_id(&ctx.unifier), Some(PrimDef::List.id()));
                 debug_assert_eq!(ty2.obj_id(&ctx.unifier), Some(PrimDef::List.id()));
@@ -1379,13 +1378,16 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
             let right_val =
                 NDArrayValue::from_ptr_val(right_val.into_pointer_value(), llvm_usize, None);
 
-            let res = if op == Operator::MatMult {
+            let res = if op.base == Operator::MatMult {
                 // MatMult is the only binop which is not an elementwise op
                 numpy::ndarray_matmul_2d(
                     generator,
                     ctx,
                     ndarray_dtype1,
-                    if is_aug_assign { Some(left_val) } else { None },
+                    match op.variant {
+                        BinopVariant::Normal => None,
+                        BinopVariant::AugAssign => Some(left_val),
+                    },
                     left_val,
                     right_val,
                 )?
@@ -1394,7 +1396,10 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                     generator,
                     ctx,
                     ndarray_dtype1,
-                    if is_aug_assign { Some(left_val) } else { None },
+                    match op.variant {
+                        BinopVariant::Normal => None,
+                        BinopVariant::AugAssign => Some(left_val),
+                    },
                     (left_val.as_base_value().into(), false),
                     (right_val.as_base_value().into(), false),
                     |generator, ctx, (lhs, rhs)| {
@@ -1405,7 +1410,6 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                             op,
                             (&Some(ndarray_dtype2), rhs),
                             ctx.current_loc,
-                            is_aug_assign,
                         )?
                         .unwrap()
                         .to_basic_value_enum(
@@ -1430,7 +1434,10 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                 generator,
                 ctx,
                 ndarray_dtype,
-                if is_aug_assign { Some(ndarray_val) } else { None },
+                match op.variant {
+                    BinopVariant::Normal => None,
+                    BinopVariant::AugAssign => Some(ndarray_val),
+                },
                 (left_val, !is_ndarray1),
                 (right_val, !is_ndarray2),
                 |generator, ctx, (lhs, rhs)| {
@@ -1441,7 +1448,6 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                         op,
                         (&Some(ndarray_dtype), rhs),
                         ctx.current_loc,
-                        is_aug_assign,
                     )?
                     .unwrap()
                     .to_basic_value_enum(ctx, generator, ndarray_dtype)
@@ -1456,13 +1462,16 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
             unreachable!("must be tobj")
         };
         let (op_name, id) = {
-            let (binop_name, binop_assign_name) =
-                (binop_name(op).into(), binop_assign_name(op).into());
+            let normal_method_name = Binop::normal(op.base).op_info().method_name;
+            let assign_method_name = Binop::aug_assign(op.base).op_info().method_name;
+
             // if is aug_assign, try aug_assign operator first
-            if is_aug_assign && fields.contains_key(&binop_assign_name) {
-                (binop_assign_name, *obj_id)
+            if op.variant == BinopVariant::AugAssign
+                && fields.contains_key(&assign_method_name.into())
+            {
+                (assign_method_name.into(), *obj_id)
             } else {
-                (binop_name, *obj_id)
+                (normal_method_name.into(), *obj_id)
             }
         };
 
@@ -1509,10 +1518,9 @@ pub fn gen_binop_expr<'ctx, G: CodeGenerator>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, '_>,
     left: &Expr<Option<Type>>,
-    op: Operator,
+    op: Binop,
     right: &Expr<Option<Type>>,
     loc: Location,
-    is_aug_assign: bool,
 ) -> Result<Option<ValueEnum<'ctx>>, String> {
     let left_val = if let Some(v) = generator.gen_expr(ctx, left)? {
         v.to_basic_value_enum(ctx, generator, left.custom.unwrap())?
@@ -1532,7 +1540,6 @@ pub fn gen_binop_expr<'ctx, G: CodeGenerator>(
         op,
         (&right.custom, right_val),
         loc,
-        is_aug_assign,
     )
 }
 
@@ -1616,7 +1623,10 @@ pub fn gen_unaryop_expr_with_values<'ctx, G: CodeGenerator>(
             if op == ast::Unaryop::Invert {
                 ast::Unaryop::Not
             } else {
-                unreachable!("ufunc {} not supported for ndarray[bool, N]", unaryop_name(op))
+                unreachable!(
+                    "ufunc {} not supported for ndarray[bool, N]",
+                    op.op_info().method_name,
+                )
             }
         } else {
             op
@@ -2698,7 +2708,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
             }
         }
         ExprKind::BinOp { op, left, right } => {
-            return gen_binop_expr(generator, ctx, left, *op, right, expr.location, false);
+            return gen_binop_expr(generator, ctx, left, Binop::normal(*op), right, expr.location);
         }
         ExprKind::UnaryOp { op, operand } => return gen_unaryop_expr(generator, ctx, *op, operand),
         ExprKind::Compare { left, ops, comparators } => {

nac3core/src/codegen/numpy.rs

@@ -11,8 +11,7 @@ use crate::{
             call_ndarray_calc_broadcast_index, call_ndarray_calc_nd_indices,
             call_ndarray_calc_size,
         },
-        llvm_intrinsics,
-        llvm_intrinsics::call_memcpy_generic,
+        llvm_intrinsics::{self, call_memcpy_generic},
         stmt::{gen_for_callback_incrementing, gen_for_range_callback, gen_if_else_expr_callback},
         CodeGenContext, CodeGenerator,
     },
@@ -22,7 +21,10 @@ use crate::{
         numpy::{make_ndarray_ty, unpack_ndarray_var_tys},
         DefinitionId,
     },
-    typecheck::typedef::{FunSignature, Type, TypeEnum},
+    typecheck::{
+        magic_methods::Binop,
+        typedef::{FunSignature, Type, TypeEnum},
+    },
 };
 use inkwell::types::{AnyTypeEnum, BasicTypeEnum, PointerType};
 use inkwell::{
@@ -1679,10 +1681,9 @@ pub fn ndarray_matmul_2d<'ctx, G: CodeGenerator>(
                     generator,
                     ctx,
                     (&Some(elem_ty), a),
-                    Operator::Mult,
+                    Binop::normal(Operator::Mult),
                     (&Some(elem_ty), b),
                     ctx.current_loc,
-                    false,
                 )?
                 .unwrap()
                 .to_basic_value_enum(ctx, generator, elem_ty)?;
@@ -1692,10 +1693,9 @@ pub fn ndarray_matmul_2d<'ctx, G: CodeGenerator>(
                     generator,
                     ctx,
                     (&Some(elem_ty), result),
-                    Operator::Add,
+                    Binop::normal(Operator::Add),
                     (&Some(elem_ty), a_mul_b),
                     ctx.current_loc,
-                    false,
                 )?
                 .unwrap()
                 .to_basic_value_enum(ctx, generator, elem_ty)?;

nac3core/src/codegen/stmt.rs

@@ -11,7 +11,10 @@ use crate::{
         gen_in_range_check,
     },
     toplevel::{helper::PrimDef, numpy::unpack_ndarray_var_tys, DefinitionId, TopLevelDef},
-    typecheck::typedef::{FunSignature, Type, TypeEnum},
+    typecheck::{
+        magic_methods::Binop,
+        typedef::{FunSignature, Type, TypeEnum},
+    },
 };
 use inkwell::{
     attributes::{Attribute, AttributeLoc},
@@ -1593,7 +1596,14 @@ pub fn gen_stmt<G: CodeGenerator>(
         StmtKind::For { .. } => generator.gen_for(ctx, stmt)?,
         StmtKind::With { .. } => generator.gen_with(ctx, stmt)?,
         StmtKind::AugAssign { target, op, value, .. } => {
-            let value = gen_binop_expr(generator, ctx, target, *op, value, stmt.location, true)?;
+            let value = gen_binop_expr(
+                generator,
+                ctx,
+                target,
+                Binop::aug_assign(*op),
+                value,
+                stmt.location,
+            )?;
             generator.gen_assign(ctx, target, value.unwrap())?;
         }
         StmtKind::Try { .. } => gen_try(generator, ctx, stmt)?,

nac3core/src/typecheck/magic_methods.rs

@@ -5,7 +5,7 @@ use crate::typecheck::{
     type_inferencer::*,
     typedef::{FunSignature, FuncArg, Type, TypeEnum, Unifier, VarMap},
 };
-use itertools::Itertools;
+use itertools::{iproduct, Itertools};
 use nac3parser::ast::StrRef;
 use nac3parser::ast::{Cmpop, Operator, Unaryop};
 use std::cmp::max;
@@ -13,67 +13,138 @@ use std::collections::HashMap;
 use std::rc::Rc;
 use strum::IntoEnumIterator;
 
-#[must_use]
-pub fn binop_name(op: Operator) -> &'static str {
-    match op {
-        Operator::Add => "__add__",
-        Operator::Sub => "__sub__",
-        Operator::Div => "__truediv__",
-        Operator::Mod => "__mod__",
-        Operator::Mult => "__mul__",
-        Operator::Pow => "__pow__",
-        Operator::BitOr => "__or__",
-        Operator::BitXor => "__xor__",
-        Operator::BitAnd => "__and__",
-        Operator::LShift => "__lshift__",
-        Operator::RShift => "__rshift__",
-        Operator::FloorDiv => "__floordiv__",
-        Operator::MatMult => "__matmul__",
+/// The variant of a binary operator.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BinopVariant {
+    /// The normal variant.
+    /// For addition, it would be `+`.
+    Normal,
+    /// The "Augmented Assigning Operator" variant.
+    /// For addition, it would be `+=`.
+    AugAssign,
+}
+
+/// A binary operator with its variant.
+#[derive(Debug, Clone, Copy)]
+pub struct Binop {
+    /// The base [`Operator`] of this binary operator.
+    pub base: Operator,
+    /// The variant of this binary operator.
+    pub variant: BinopVariant,
+}
+
+impl Binop {
+    /// Make a [`Binop`] of the normal variant from an [`Operator`].
+    #[must_use]
+    pub fn normal(base: Operator) -> Self {
+        Binop { base, variant: BinopVariant::Normal }
+    }
+
+    /// Make a [`Binop`] of the aug assign variant from an [`Operator`].
+    #[must_use]
+    pub fn aug_assign(base: Operator) -> Self {
+        Binop { base, variant: BinopVariant::AugAssign }
     }
 }
 
-#[must_use]
-pub fn binop_assign_name(op: Operator) -> &'static str {
-    match op {
-        Operator::Add => "__iadd__",
-        Operator::Sub => "__isub__",
-        Operator::Div => "__itruediv__",
-        Operator::Mod => "__imod__",
-        Operator::Mult => "__imul__",
-        Operator::Pow => "__ipow__",
-        Operator::BitOr => "__ior__",
-        Operator::BitXor => "__ixor__",
-        Operator::BitAnd => "__iand__",
-        Operator::LShift => "__ilshift__",
-        Operator::RShift => "__irshift__",
-        Operator::FloorDiv => "__ifloordiv__",
-        Operator::MatMult => "__imatmul__",
-    }
+/// Details about an operator (unary, binary, etc...) in Python
+#[derive(Debug, Clone, Copy)]
+pub struct OpInfo {
+    /// The method name of the binary operator.
+    /// For addition, this would be `__add__`, and `__iadd__` if
+    /// it is the augmented assigning variant.
+    pub method_name: &'static str,
+    /// The symbol of the binary operator.
+    /// For addition, this would be `+`, and `+=` if
+    /// it is the augmented assigning variant.
+    pub symbol: &'static str,
 }
 
-#[must_use]
-pub fn unaryop_name(op: Unaryop) -> &'static str {
-    match op {
-        Unaryop::UAdd => "__pos__",
-        Unaryop::USub => "__neg__",
-        Unaryop::Not => "__not__",
-        Unaryop::Invert => "__inv__",
-    }
+/// Helper macro to conveniently build an [`OpInfo`].
+///
+/// Example usage: `make_info("add", "+")` generates `OpInfo { name: "__add__", symbol: "+" }`
+macro_rules! make_op_info {
+    ($name:expr, $symbol:expr) => {
+        OpInfo { method_name: concat!("__", $name, "__"), symbol: $symbol }
+    };
 }
 
-#[must_use]
-pub fn comparison_name(op: Cmpop) -> Option<&'static str> {
+pub trait HasOpInfo {
+    fn op_info(&self) -> OpInfo;
+}
+
+fn try_get_cmpop_info(op: Cmpop) -> Option<OpInfo> {
     match op {
-        Cmpop::Lt => Some("__lt__"),
-        Cmpop::LtE => Some("__le__"),
-        Cmpop::Gt => Some("__gt__"),
-        Cmpop::GtE => Some("__ge__"),
-        Cmpop::Eq => Some("__eq__"),
-        Cmpop::NotEq => Some("__ne__"),
+        Cmpop::Lt => Some(make_op_info!("lt", "<")),
+        Cmpop::LtE => Some(make_op_info!("le", "<=")),
+        Cmpop::Gt => Some(make_op_info!("gt", ">")),
+        Cmpop::GtE => Some(make_op_info!("ge", ">=")),
+        Cmpop::Eq => Some(make_op_info!("eq", "==")),
+        Cmpop::NotEq => Some(make_op_info!("ne", "!=")),
         _ => None,
     }
 }
 
+impl OpInfo {
+    #[must_use]
+    pub fn supports_cmpop(op: Cmpop) -> bool {
+        try_get_cmpop_info(op).is_some()
+    }
+}
+
+impl HasOpInfo for Cmpop {
+    fn op_info(&self) -> OpInfo {
+        try_get_cmpop_info(*self).expect("{self:?} is not supported")
+    }
+}
+
+impl HasOpInfo for Binop {
+    fn op_info(&self) -> OpInfo {
+        // Helper macro to generate both the normal variant [`OpInfo`] and the
+        // augmented assigning variant [`OpInfo`] for a binary operator conveniently.
+        macro_rules! info {
+            ($name:literal, $symbol:literal) => {
+                (
+                    make_op_info!($name, $symbol),
+                    make_op_info!(concat!("i", $name), concat!($symbol, "=")),
+                )
+            };
+        }
+
+        let (normal_variant, aug_assign_variant) = match self.base {
+            Operator::Add => info!("add", "+"),
+            Operator::Sub => info!("sub", "-"),
+            Operator::Div => info!("truediv", "/"),
+            Operator::Mod => info!("mod", "%"),
+            Operator::Mult => info!("mul", "*"),
+            Operator::Pow => info!("pow", "**"),
+            Operator::BitOr => info!("or", "|"),
+            Operator::BitXor => info!("xor", "^"),
+            Operator::BitAnd => info!("and", "&"),
+            Operator::LShift => info!("lshift", "<<"),
+            Operator::RShift => info!("rshift", ">>"),
+            Operator::FloorDiv => info!("floordiv", "//"),
+            Operator::MatMult => info!("matmul", "@"),
+        };
+
+        match self.variant {
+            BinopVariant::Normal => normal_variant,
+            BinopVariant::AugAssign => aug_assign_variant,
+        }
+    }
+}
+
+impl HasOpInfo for Unaryop {
+    fn op_info(&self) -> OpInfo {
+        match self {
+            Unaryop::UAdd => make_op_info!("pos", "+"),
+            Unaryop::USub => make_op_info!("neg", "-"),
+            Unaryop::Not => make_op_info!("not", "not"), // i.e., `not False`, so the symbol is just `not`.
+            Unaryop::Invert => make_op_info!("inv", "~"),
+        }
+    }
+}
+
 pub(super) fn with_fields<F>(unifier: &mut Unifier, ty: Type, f: F)
 where
     F: FnOnce(&mut Unifier, &mut HashMap<StrRef, (Type, bool)>),
@@ -115,23 +186,9 @@ pub fn impl_binop(
 
         let ret_ty = ret_ty.unwrap_or_else(|| unifier.get_fresh_var(None, None).ty);
 
-        for op in ops {
-            fields.insert(binop_name(*op).into(), {
-                (
-                    unifier.add_ty(TypeEnum::TFunc(FunSignature {
-                        ret: ret_ty,
-                        vars: function_vars.clone(),
-                        args: vec![FuncArg {
-                            ty: other_ty,
-                            default_value: None,
-                            name: "other".into(),
-                        }],
-                    })),
-                    false,
-                )
-            });
-
-            fields.insert(binop_assign_name(*op).into(), {
+        for (base_op, variant) in iproduct!(ops, [BinopVariant::Normal, BinopVariant::AugAssign]) {
+            let op = Binop { base: *base_op, variant };
+            fields.insert(op.op_info().method_name.into(), {
                 (
                     unifier.add_ty(TypeEnum::TFunc(FunSignature {
                         ret: ret_ty,
@@ -155,7 +212,7 @@ pub fn impl_unaryop(unifier: &mut Unifier, ty: Type, ret_ty: Option<Type>, ops:
 
         for op in ops {
             fields.insert(
-                unaryop_name(*op).into(),
+                op.op_info().method_name.into(),
                 (
                     unifier.add_ty(TypeEnum::TFunc(FunSignature {
                         ret: ret_ty,
@@ -195,7 +252,7 @@ pub fn impl_cmpop(
 
         for op in ops {
             fields.insert(
-                comparison_name(*op).unwrap().into(),
+                op.op_info().method_name.into(),
                 (
                     unifier.add_ty(TypeEnum::TFunc(FunSignature {
                         ret: ret_ty,
@@ -429,18 +486,20 @@ pub fn typeof_binop(
     lhs: Type,
     rhs: Type,
 ) -> Result<Option<Type>, String> {
+    let op = Binop { base: op, variant: BinopVariant::Normal };
+
     let is_left_list = lhs.obj_id(unifier).is_some_and(|id| id == PrimDef::List.id());
     let is_right_list = rhs.obj_id(unifier).is_some_and(|id| id == PrimDef::List.id());
     let is_left_ndarray = lhs.obj_id(unifier).is_some_and(|id| id == PrimDef::NDArray.id());
     let is_right_ndarray = rhs.obj_id(unifier).is_some_and(|id| id == PrimDef::NDArray.id());
 
-    Ok(Some(match op {
+    Ok(Some(match op.base {
         Operator::Add | Operator::Sub | Operator::Mult | Operator::Mod | Operator::FloorDiv => {
             if is_left_list || is_right_list {
-                if ![Operator::Add, Operator::Mult].contains(&op) {
+                if ![Operator::Add, Operator::Mult].contains(&op.base) {
                     return Err(format!(
                         "Binary operator {} not supported for list",
-                        binop_name(op)
+                        op.op_info().symbol
                     ));
                 }
 

nac3core/src/typecheck/type_error.rs

@@ -1,11 +1,14 @@
 use std::collections::HashMap;
 use std::fmt::Display;
 
-use crate::typecheck::typedef::TypeEnum;
+use crate::typecheck::{magic_methods::HasOpInfo, typedef::TypeEnum};
 
-use super::typedef::{RecordKey, Type, Unifier};
+use super::{
+    magic_methods::Binop,
+    typedef::{RecordKey, Type, Unifier},
+};
 use itertools::Itertools;
-use nac3parser::ast::{Location, StrRef};
+use nac3parser::ast::{Cmpop, Location, StrRef};
 
 #[derive(Debug, Clone)]
 pub enum TypeErrorKind {
@@ -26,6 +29,18 @@ pub enum TypeErrorKind {
         expected: Type,
         got: Type,
     },
+    UnsupportedBinaryOpTypes {
+        operator: Binop,
+        lhs_type: Type,
+        rhs_type: Type,
+        expected_rhs_type: Type,
+    },
+    UnsupportedComparsionOpTypes {
+        operator: Cmpop,
+        lhs_type: Type,
+        rhs_type: Type,
+        expected_rhs_type: Type,
+    },
     FieldUnificationError {
         field: RecordKey,
         types: (Type, Type),
@@ -101,6 +116,26 @@ impl<'a> Display for DisplayTypeError<'a> {
                 let args = missing_arg_names.iter().join(", ");
                 write!(f, "Missing arguments: {args}")
             }
+            UnsupportedBinaryOpTypes { operator, lhs_type, rhs_type, expected_rhs_type } => {
+                let op_symbol = operator.op_info().symbol;
+
+                let lhs_type_str = self.unifier.stringify_with_notes(*lhs_type, &mut notes);
+                let rhs_type_str = self.unifier.stringify_with_notes(*rhs_type, &mut notes);
+                let expected_rhs_type_str =
+                    self.unifier.stringify_with_notes(*expected_rhs_type, &mut notes);
+
+                write!(f, "Unsupported operand type(s) for {op_symbol}: '{lhs_type_str}' and '{rhs_type_str}' (right operand should have type {expected_rhs_type_str})")
+            }
+            UnsupportedComparsionOpTypes { operator, lhs_type, rhs_type, expected_rhs_type } => {
+                let op_symbol = operator.op_info().symbol;
+
+                let lhs_type_str = self.unifier.stringify_with_notes(*lhs_type, &mut notes);
+                let rhs_type_str = self.unifier.stringify_with_notes(*rhs_type, &mut notes);
+                let expected_rhs_type_str =
+                    self.unifier.stringify_with_notes(*expected_rhs_type, &mut notes);
+
+                write!(f, "'{op_symbol}' not supported between instances of '{lhs_type_str}' and '{rhs_type_str}' (right operand should have type {expected_rhs_type_str})")
+            }
             UnknownArgName(name) => {
                 write!(f, "Unknown argument name: {name}")
             }

nac3core/src/typecheck/type_inferencer/mod.rs

@@ -4,6 +4,7 @@ use std::iter::once;
 use std::ops::Not;
 use std::{cell::RefCell, sync::Arc};
 
+use super::typedef::OperatorInfo;
 use super::{
     magic_methods::*,
     type_error::TypeError,
@@ -491,7 +492,8 @@ impl<'a> Fold<()> for Inferencer<'a> {
                 (None, None) => {}
             },
             ast::StmtKind::AugAssign { target, op, value, .. } => {
-                let res_ty = self.infer_bin_ops(stmt.location, target, *op, value, true)?;
+                let res_ty =
+                    self.infer_bin_ops(stmt.location, target, Binop::aug_assign(*op), value)?;
                 self.unify(res_ty, target.custom.unwrap(), &stmt.location)?;
             }
             ast::StmtKind::Assert { test, msg, .. } => {
@@ -573,7 +575,7 @@ impl<'a> Fold<()> for Inferencer<'a> {
             }
             ExprKind::BoolOp { values, .. } => Some(self.infer_bool_ops(values)?),
             ExprKind::BinOp { left, op, right } => {
-                Some(self.infer_bin_ops(expr.location, left, *op, right, false)?)
+                Some(self.infer_bin_ops(expr.location, left, Binop::normal(*op), right)?)
             }
             ExprKind::UnaryOp { op, operand } => {
                 Some(self.infer_unary_ops(expr.location, *op, operand)?)
@@ -640,6 +642,7 @@ impl<'a> Inferencer<'a> {
         obj: Type,
         params: Vec<Type>,
         ret: Option<Type>,
+        operator_info: Option<OperatorInfo>,
     ) -> InferenceResult {
         if let TypeEnum::TObj { params: class_params, fields, .. } = &*self.unifier.get_ty(obj) {
             if class_params.is_empty() {
@@ -653,6 +656,7 @@ impl<'a> Inferencer<'a> {
                                 ret: sign.ret,
                                 fun: RefCell::new(None),
                                 loc: Some(location),
+                                operator_info,
                             };
                             if let Some(ret) = ret {
                                 self.unifier
@@ -687,6 +691,7 @@ impl<'a> Inferencer<'a> {
             ret,
             fun: RefCell::new(None),
             loc: Some(location),
+            operator_info,
         });
         self.calls.insert(location.into(), call);
         let call = self.unifier.add_ty(TypeEnum::TCall(vec![call]));
@@ -1522,6 +1527,7 @@ impl<'a> Inferencer<'a> {
                     fun: RefCell::new(None),
                     ret: sign.ret,
                     loc: Some(location),
+                    operator_info: None,
                 };
                 self.unifier.unify_call(&call, func.custom.unwrap(), sign).map_err(|e| {
                     HashSet::from([e.at(Some(location)).to_display(self.unifier).to_string()])
@@ -1544,6 +1550,7 @@ impl<'a> Inferencer<'a> {
             fun: RefCell::new(None),
             ret,
             loc: Some(location),
+            operator_info: None,
         });
         self.calls.insert(location.into(), call);
         let call = self.unifier.add_ty(TypeEnum::TCall(vec![call]));
@@ -1729,9 +1736,8 @@ impl<'a> Inferencer<'a> {
         &mut self,
         location: Location,
         left: &ast::Expr<Option<Type>>,
-        op: ast::Operator,
+        op: Binop,
         right: &ast::Expr<Option<Type>>,
-        is_aug_assign: bool,
     ) -> InferenceResult {
         let left_ty = left.custom.unwrap();
         let right_ty = right.custom.unwrap();
@@ -1739,27 +1745,40 @@ impl<'a> Inferencer<'a> {
         let method = if let TypeEnum::TObj { fields, .. } =
             self.unifier.get_ty_immutable(left_ty).as_ref()
         {
-            let (binop_name, binop_assign_name) =
-                (binop_name(op).into(), binop_assign_name(op).into());
+            let normal_method_name = Binop::normal(op.base).op_info().method_name;
+            let assign_method_name = Binop::aug_assign(op.base).op_info().method_name;
+
             // if is aug_assign, try aug_assign operator first
-            if is_aug_assign && fields.contains_key(&binop_assign_name) {
-                binop_assign_name
+            if op.variant == BinopVariant::AugAssign
+                && fields.contains_key(&assign_method_name.into())
+            {
+                assign_method_name
             } else {
-                binop_name
+                normal_method_name
             }
         } else {
-            binop_name(op).into()
+            op.op_info().method_name
         };
 
-        let ret = if is_aug_assign {
-            // The type of augmented assignment operator should never change
-            Some(left_ty)
-        } else {
-            typeof_binop(self.unifier, self.primitives, op, left_ty, right_ty)
-                .map_err(|e| HashSet::from([format!("{e} (at {location})")]))?
+        let ret = match op.variant {
+            BinopVariant::Normal => {
+                typeof_binop(self.unifier, self.primitives, op.base, left_ty, right_ty)
+                    .map_err(|e| HashSet::from([format!("{e} (at {location})")]))?
+            }
+            BinopVariant::AugAssign => {
+                // The type of augmented assignment operator should never change
+                Some(left_ty)
+            }
         };
 
-        self.build_method_call(location, method, left_ty, vec![right_ty], ret)
+        self.build_method_call(
+            location,
+            method.into(),
+            left_ty,
+            vec![right_ty],
+            ret,
+            Some(OperatorInfo::IsBinaryOp { self_type: left.custom.unwrap(), operator: op }),
+        )
     }
 
     fn infer_unary_ops(
@@ -1768,12 +1787,19 @@ impl<'a> Inferencer<'a> {
         op: ast::Unaryop,
         operand: &ast::Expr<Option<Type>>,
     ) -> InferenceResult {
-        let method = unaryop_name(op).into();
+        let method = op.op_info().method_name.into();
 
         let ret = typeof_unaryop(self.unifier, self.primitives, op, operand.custom.unwrap())
             .map_err(|e| HashSet::from([format!("{e} (at {location})")]))?;
 
-        self.build_method_call(location, method, operand.custom.unwrap(), vec![], ret)
+        self.build_method_call(
+            location,
+            method,
+            operand.custom.unwrap(),
+            vec![],
+            ret,
+            Some(OperatorInfo::IsUnaryOp { self_type: operand.custom.unwrap(), operator: op }),
+        )
     }
 
     fn infer_compare(
@@ -1798,9 +1824,11 @@ impl<'a> Inferencer<'a> {
 
         let mut res = None;
         for (a, b, c) in izip!(once(left).chain(comparators), comparators, ops) {
-            let method = comparison_name(*c)
-                .ok_or_else(|| HashSet::from(["unsupported comparator".to_string()]))?
-                .into();
+            if !OpInfo::supports_cmpop(*c) {
+                return Err(HashSet::from(["unsupported comparator".to_string()]));
+            }
+
+            let method = c.op_info().method_name.into();
 
             let ret = typeof_cmpop(
                 self.unifier,
@@ -1817,6 +1845,10 @@ impl<'a> Inferencer<'a> {
                 a.custom.unwrap(),
                 vec![b.custom.unwrap()],
                 ret,
+                Some(OperatorInfo::IsComparisonOp {
+                    self_type: left.custom.unwrap(),
+                    operator: *c,
+                }),
             )?);
         }
 

nac3core/src/typecheck/typedef/mod.rs

@@ -8,12 +8,15 @@ use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 use std::{borrow::Cow, collections::HashSet};
 
-use nac3parser::ast::{Location, StrRef};
+use nac3parser::ast::{Cmpop, Location, StrRef, Unaryop};
 
+use super::magic_methods::Binop;
 use super::type_error::{TypeError, TypeErrorKind};
 use super::unification_table::{UnificationKey, UnificationTable};
 use crate::symbol_resolver::SymbolValue;
-use crate::toplevel::{helper::PrimDef, DefinitionId, TopLevelContext, TopLevelDef};
+use crate::toplevel::helper::PrimDef;
+use crate::toplevel::{DefinitionId, TopLevelContext, TopLevelDef};
+use crate::typecheck::magic_methods::OpInfo;
 use crate::typecheck::type_inferencer::PrimitiveStore;
 
 #[cfg(test)]
@@ -73,6 +76,28 @@ pub fn iter_type_vars(var_map: &VarMap) -> impl Iterator<Item = TypeVar> + '_ {
     var_map.iter().map(|(&id, &ty)| TypeVar { id, ty })
 }
 
+#[derive(Debug, Clone)]
+pub enum OperatorInfo {
+    /// The call was written as an unary operation, e.g., `~a` or `not a`.
+    IsUnaryOp {
+        /// The [`Type`] of the `self` object
+        self_type: Type,
+        operator: Unaryop,
+    },
+    /// The call was written as a binary operation, e.g., `a + b` or `a += b`.
+    IsBinaryOp {
+        /// The [`Type`] of the `self` object
+        self_type: Type,
+        operator: Binop,
+    },
+    /// The call was written as a binary comparison operation, e.g., `a < b`.
+    IsComparisonOp {
+        /// The [`Type`] of the `self` object
+        self_type: Type,
+        operator: Cmpop,
+    },
+}
+
 #[derive(Clone)]
 pub struct Call {
     pub posargs: Vec<Type>,
@@ -80,6 +105,9 @@ pub struct Call {
     pub ret: Type,
     pub fun: RefCell<Option<Type>>,
     pub loc: Option<Location>,
+
+    /// Details about the associated Python user operator expression of this call, if any.
+    pub operator_info: Option<OperatorInfo>,
 }
 
 #[derive(Debug, Clone)]
@@ -627,111 +655,178 @@ impl Unifier {
         let TypeEnum::TFunc(signature) = &*self.get_ty(b) else { unreachable!() };
 
         // Get details about the input arguments
-        let Call { posargs, kwargs, ret, fun, loc } = call;
+        let Call { posargs, kwargs, ret, fun, loc, operator_info } = call;
         let num_args = posargs.len() + kwargs.len();
 
-        // Now we check the arguments against the parameters
+        // Now we check the arguments against the parameters,
+        // and depending on what `call_info` is, we might change how the behavior `unify_call()`
+        // in hopes to improve user error messages when type checking fails.
+        match operator_info {
+            Some(OperatorInfo::IsBinaryOp { self_type, operator }) => {
+                // The call is written in the form of (say) `a + b`.
+                // Technically, it is `a.__add__(b)`, and they have the following constraints:
+                assert_eq!(posargs.len(), 1);
+                assert_eq!(kwargs.len(), 0);
+                assert_eq!(num_params, 1);
 
-        // Helper lambdas
-        let mut type_check_arg = |param_name, expected_arg_ty, arg_ty| {
-            let ok = self.unify_impl(expected_arg_ty, arg_ty, false).is_ok();
-            if ok {
-                Ok(())
-            } else {
-                // Typecheck failed, throw an error.
-                self.restore_snapshot();
-                Err(TypeError::new(
-                    TypeErrorKind::IncorrectArgType {
-                        name: param_name,
-                        expected: expected_arg_ty,
-                        got: arg_ty,
-                    },
-                    *loc,
-                ))
+                let other_type = posargs[0]; // the second operand
+                let expected_other_type = signature.args[0].ty;
+
+                let ok = self.unify_impl(expected_other_type, other_type, false).is_ok();
+                if !ok {
+                    self.restore_snapshot();
+                    return Err(TypeError::new(
+                        TypeErrorKind::UnsupportedBinaryOpTypes {
+                            operator: *operator,
+                            lhs_type: *self_type,
+                            rhs_type: other_type,
+                            expected_rhs_type: expected_other_type,
+                        },
+                        *loc,
+                    ));
+                }
             }
-        };
+            Some(OperatorInfo::IsComparisonOp { self_type, operator })
+                if OpInfo::supports_cmpop(*operator) // Otherwise that comparison operator is not supported.
+                =>
+            {
+                // The call is written in the form of (say) `a <= b`.
+                // Technically, it is `a.__le__(b)`, and they have the following constraints:
+                assert_eq!(posargs.len(), 1);
+                assert_eq!(kwargs.len(), 0);
+                assert_eq!(num_params, 1);
 
-        // Check for "too many arguments"
-        if num_params < posargs.len() {
-            let expected_min_count =
-                signature.args.iter().filter(|param| param.is_required()).count();
-            let expected_max_count = num_params;
+                let other_type = posargs[0]; // the second operand
+                let expected_other_type = signature.args[0].ty;
 
-            self.restore_snapshot();
-            return Err(TypeError::new(
-                TypeErrorKind::TooManyArguments {
-                    expected_min_count,
-                    expected_max_count,
-                    got_count: num_args,
-                },
-                *loc,
-            ));
-        }
-
-        // NOTE: order of `param_info_by_name` is leveraged, so use an IndexMap
-        let mut param_info_by_name: IndexMap<StrRef, ParamInfo> = signature
-            .args
-            .iter()
-            .map(|arg| (arg.name, ParamInfo { has_been_supplied: false, param: arg }))
-            .collect();
-
-        // Now consume all positional arguments and typecheck them.
-        for (&arg_ty, param) in zip(posargs, signature.args.iter()) {
-            // We will also use this opportunity to mark the corresponding `param_info` as having been supplied.
-            let param_info = param_info_by_name.get_mut(&param.name).unwrap();
-            param_info.has_been_supplied = true;
-
-            // Typecheck
-            type_check_arg(param.name, param.ty, arg_ty)?;
-        }
-
-        // Now consume all keyword arguments and typecheck them.
-        for (&param_name, &arg_ty) in kwargs {
-            // We will also use this opportunity to check if this keyword argument is "legal".
-
-            let Some(param_info) = param_info_by_name.get_mut(&param_name) else {
-                self.restore_snapshot();
-                return Err(TypeError::new(TypeErrorKind::UnknownArgName(param_name), *loc));
-            };
-
-            if param_info.has_been_supplied {
-                // NOTE: Duplicate keyword argument (i.e., `hello(1, 2, 3, arg = 4, arg = 5)`)
-                // is IMPOSSIBLE as the parser would have already failed.
-                // We only have to care about "got multiple values for XYZ"
-
-                self.restore_snapshot();
-                return Err(TypeError::new(
-                    TypeErrorKind::GotMultipleValues { name: param_name },
-                    *loc,
-                ));
+                let ok = self.unify_impl(expected_other_type, other_type, false).is_ok();
+                if !ok {
+                    self.restore_snapshot();
+                    return Err(TypeError::new(
+                        TypeErrorKind::UnsupportedComparsionOpTypes {
+                            operator: *operator,
+                            lhs_type: *self_type,
+                            rhs_type: other_type,
+                            expected_rhs_type: expected_other_type,
+                        },
+                        *loc,
+                    ));
+                }
             }
+            _ => {
+                // Handle [`CallInfo::IsNormalFunctionCall`] and other uninteresting variants
+                // of [`CallInfo`] (e.g, `CallInfo::IsUnaryOp` and unsupported comparison operators)
 
-            param_info.has_been_supplied = true;
+                // Helper lambdas
+                let mut type_check_arg = |param_name, expected_arg_ty, arg_ty| {
+                    let ok = self.unify_impl(expected_arg_ty, arg_ty, false).is_ok();
+                    if ok {
+                        Ok(())
+                    } else {
+                        // Typecheck failed, throw an error.
+                        self.restore_snapshot();
+                        Err(TypeError::new(
+                            TypeErrorKind::IncorrectArgType {
+                                name: param_name,
+                                expected: expected_arg_ty,
+                                got: arg_ty,
+                            },
+                            *loc,
+                        ))
+                    }
+                };
 
-            // Typecheck
-            type_check_arg(param_name, param_info.param.ty, arg_ty)?;
-        }
+                // Check for "too many arguments"
+                if num_params < posargs.len() {
+                    let expected_min_count =
+                        signature.args.iter().filter(|param| param.is_required()).count();
+                    let expected_max_count = num_params;
 
-        // After checking posargs and kwargs, check if there are any
-        // unsupplied required parameters, and throw an error if they exist.
-        let missing_arg_names = param_info_by_name
-            .values()
-            .filter(|param_info| param_info.param.is_required() && !param_info.has_been_supplied)
-            .map(|param_info| param_info.param.name)
-            .collect_vec();
-        if !missing_arg_names.is_empty() {
-            self.restore_snapshot();
-            return Err(TypeError::new(TypeErrorKind::MissingArgs { missing_arg_names }, *loc));
-        }
+                    self.restore_snapshot();
+                    return Err(TypeError::new(
+                        TypeErrorKind::TooManyArguments {
+                            expected_min_count,
+                            expected_max_count,
+                            got_count: num_args,
+                        },
+                        *loc,
+                    ));
+                }
 
-        // Finally, check the Call's return type
-        self.unify_impl(*ret, signature.ret, false).map_err(|mut err| {
-            self.restore_snapshot();
-            if err.loc.is_none() {
-                err.loc = *loc;
+                // NOTE: order of `param_info_by_name` is leveraged, so use an IndexMap
+                let mut param_info_by_name: IndexMap<StrRef, ParamInfo> = signature
+                    .args
+                    .iter()
+                    .map(|arg| (arg.name, ParamInfo { has_been_supplied: false, param: arg }))
+                    .collect();
+
+                // Now consume all positional arguments and typecheck them.
+                for (&arg_ty, param) in zip(posargs, signature.args.iter()) {
+                    // We will also use this opportunity to mark the corresponding `param_info` as having been supplied.
+                    let param_info = param_info_by_name.get_mut(&param.name).unwrap();
+                    param_info.has_been_supplied = true;
+
+                    // Typecheck
+                    type_check_arg(param.name, param.ty, arg_ty)?;
+                }
+
+                // Now consume all keyword arguments and typecheck them.
+                for (&param_name, &arg_ty) in kwargs {
+                    // We will also use this opportunity to check if this keyword argument is "legal".
+
+                    let Some(param_info) = param_info_by_name.get_mut(&param_name) else {
+                        self.restore_snapshot();
+                        return Err(TypeError::new(
+                            TypeErrorKind::UnknownArgName(param_name),
+                            *loc,
+                        ));
+                    };
+
+                    if param_info.has_been_supplied {
+                        // NOTE: Duplicate keyword argument (i.e., `hello(1, 2, 3, arg = 4, arg = 5)`)
+                        // is IMPOSSIBLE as the parser would have already failed.
+                        // We only have to care about "got multiple values for XYZ"
+
+                        self.restore_snapshot();
+                        return Err(TypeError::new(
+                            TypeErrorKind::GotMultipleValues { name: param_name },
+                            *loc,
+                        ));
+                    }
+
+                    param_info.has_been_supplied = true;
+
+                    // Typecheck
+                    type_check_arg(param_name, param_info.param.ty, arg_ty)?;
+                }
+
+                // After checking posargs and kwargs, check if there are any
+                // unsupplied required parameters, and throw an error if they exist.
+                let missing_arg_names = param_info_by_name
+                    .values()
+                    .filter(|param_info| {
+                        param_info.param.is_required() && !param_info.has_been_supplied
+                    })
+                    .map(|param_info| param_info.param.name)
+                    .collect_vec();
+                if !missing_arg_names.is_empty() {
+                    self.restore_snapshot();
+                    return Err(TypeError::new(
+                        TypeErrorKind::MissingArgs { missing_arg_names },
+                        *loc,
+                    ));
+                }
+
+                // Finally, check the Call's return type
+                self.unify_impl(*ret, signature.ret, false).map_err(|mut err| {
+                    self.restore_snapshot();
+                    if err.loc.is_none() {
+                        err.loc = *loc;
+                    }
+                    err
+                })?;
             }
-            err
-        })?;
+        }
 
         *fun.borrow_mut() = Some(b);