From d9f96dab336f27f4a8dae36d2f4d64fbc7f514e7 Mon Sep 17 00:00:00 2001
From: David Mak <chmakac@connect.ust.hk>
Date: Fri, 23 Aug 2024 13:10:55 +0800
Subject: [PATCH] [core] Add codegen_unreachable

---
 nac3core/src/codegen/builtin_fns.rs |  28 +++----
 nac3core/src/codegen/expr.rs        | 109 ++++++++++++++++------------
 nac3core/src/codegen/irrt/mod.rs    |  23 +++---
 nac3core/src/codegen/mod.rs         |  16 ++++
 nac3core/src/codegen/numpy.rs       |  26 ++++---
 nac3core/src/codegen/stmt.rs        |  46 ++++++------
 6 files changed, 145 insertions(+), 103 deletions(-)

diff --git a/nac3core/src/codegen/builtin_fns.rs b/nac3core/src/codegen/builtin_fns.rs
index 9914d81c..5608ec71 100644
--- a/nac3core/src/codegen/builtin_fns.rs
+++ b/nac3core/src/codegen/builtin_fns.rs
@@ -9,6 +9,7 @@ use crate::codegen::classes::{
 };
 use crate::codegen::expr::destructure_range;
 use crate::codegen::irrt::calculate_len_for_slice_range;
+use crate::codegen::macros::codegen_unreachable;
 use crate::codegen::numpy::ndarray_elementwise_unaryop_impl;
 use crate::codegen::stmt::gen_for_callback_incrementing;
 use crate::codegen::{extern_fns, irrt, llvm_intrinsics, numpy, CodeGenContext, CodeGenerator};
@@ -20,7 +21,8 @@ use crate::typecheck::typedef::{Type, TypeEnum};
 ///
 /// The generated message will contain the function name and the name of the unsupported type.
 fn unsupported_type(ctx: &CodeGenContext<'_, '_>, fn_name: &str, tys: &[Type]) -> ! {
-    unreachable!(
+    codegen_unreachable!(
+        ctx,
         "{fn_name}() not supported for '{}'",
         tys.iter().map(|ty| format!("'{}'", ctx.unifier.stringify(*ty))).join(", "),
     )
@@ -82,7 +84,7 @@ pub fn call_len<'ctx, G: CodeGenerator + ?Sized>(
 
                 ctx.builder.build_int_truncate_or_bit_cast(len, llvm_i32, "len").unwrap()
             }
-            _ => unreachable!(),
+            _ => codegen_unreachable!(ctx),
         }
     })
 }
@@ -784,7 +786,7 @@ pub fn call_numpy_minimum<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -888,7 +890,7 @@ pub fn call_numpy_max_min<'ctx, G: CodeGenerator + ?Sized>(
             match fn_name {
                 "np_argmin" | "np_argmax" => llvm_int64.const_zero().into(),
                 "np_max" | "np_min" => a,
-                _ => unreachable!(),
+                _ => codegen_unreachable!(ctx),
             }
         }
         BasicValueEnum::PointerValue(n)
@@ -943,7 +945,7 @@ pub fn call_numpy_max_min<'ctx, G: CodeGenerator + ?Sized>(
                         "np_argmax" | "np_max" => {
                             call_max(ctx, (elem_ty, accumulator), (elem_ty, elem))
                         }
-                        _ => unreachable!(),
+                        _ => codegen_unreachable!(ctx),
                     };
 
                     let updated_idx = match (accumulator, result) {
@@ -980,7 +982,7 @@ pub fn call_numpy_max_min<'ctx, G: CodeGenerator + ?Sized>(
             match fn_name {
                 "np_argmin" | "np_argmax" => ctx.builder.build_load(res_idx, "").unwrap(),
                 "np_max" | "np_min" => ctx.builder.build_load(accumulator_addr, "").unwrap(),
-                _ => unreachable!(),
+                _ => codegen_unreachable!(ctx),
             }
         }
 
@@ -1046,7 +1048,7 @@ pub fn call_numpy_maximum<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1486,7 +1488,7 @@ pub fn call_numpy_arctan2<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1553,7 +1555,7 @@ pub fn call_numpy_copysign<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1620,7 +1622,7 @@ pub fn call_numpy_fmax<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1687,7 +1689,7 @@ pub fn call_numpy_fmin<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1810,7 +1812,7 @@ pub fn call_numpy_hypot<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
@@ -1877,7 +1879,7 @@ pub fn call_numpy_nextafter<'ctx, G: CodeGenerator + ?Sized>(
             } else if is_ndarray2 {
                 unpack_ndarray_var_tys(&mut ctx.unifier, x2_ty).0
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             let x1_scalar_ty = if is_ndarray1 { dtype } else { x1_ty };
diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index 50d70eb7..18b490d7 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -11,6 +11,7 @@ use crate::{
             call_expect, call_float_floor, call_float_pow, call_float_powi, call_int_smax,
             call_int_umin, call_memcpy_generic,
         },
+        macros::codegen_unreachable,
         need_sret, numpy,
         stmt::{
             gen_for_callback_incrementing, gen_if_callback, gen_if_else_expr_callback, gen_raise,
@@ -112,7 +113,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         let obj_id = match &*self.unifier.get_ty(ty) {
             TypeEnum::TObj { obj_id, .. } => *obj_id,
             // we cannot have other types, virtual type should be handled by function calls
-            _ => unreachable!(),
+            _ => codegen_unreachable!(self),
         };
         let def = &self.top_level.definitions.read()[obj_id.0];
         let (index, value) = if let TopLevelDef::Class { fields, attributes, .. } = &*def.read() {
@@ -123,7 +124,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                 (attribute_index.0, Some(attribute_index.1 .2.clone()))
             }
         } else {
-            unreachable!()
+            codegen_unreachable!(self)
         };
         (index, value)
     }
@@ -133,7 +134,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             TypeEnum::TObj { fields, .. } => {
                 fields.iter().find_position(|x| *x.0 == attr).unwrap().0
             }
-            _ => unreachable!(),
+            _ => codegen_unreachable!(self),
         }
     }
 
@@ -188,7 +189,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                     {
                         *params.iter().next().unwrap().1
                     }
-                    _ => unreachable!("must be option type"),
+                    _ => codegen_unreachable!(self, "must be option type"),
                 };
                 let val = self.gen_symbol_val(generator, v, ty);
                 let ptr = generator
@@ -204,7 +205,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                     {
                         *params.iter().next().unwrap().1
                     }
-                    _ => unreachable!("must be option type"),
+                    _ => codegen_unreachable!(self, "must be option type"),
                 };
                 let actual_ptr_type =
                     self.get_llvm_type(generator, ty).ptr_type(AddressSpace::default());
@@ -271,7 +272,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                 {
                     self.ctx.i64_type()
                 } else {
-                    unreachable!()
+                    codegen_unreachable!(self)
                 };
                 Some(ty.const_int(*val as u64, false).into())
             }
@@ -285,7 +286,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                 let (types, is_vararg_ctx) = if let TypeEnum::TTuple { ty, is_vararg_ctx } = &*ty {
                     (ty.clone(), *is_vararg_ctx)
                 } else {
-                    unreachable!()
+                    codegen_unreachable!(self)
                 };
                 let values = zip(types, v.iter())
                     .map_while(|(ty, v)| self.gen_const(generator, v, ty))
@@ -330,7 +331,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
 
                 None
             }
-            _ => unreachable!(),
+            _ => codegen_unreachable!(self),
         }
     }
 
@@ -344,7 +345,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         signed: bool,
     ) -> BasicValueEnum<'ctx> {
         let (BasicValueEnum::IntValue(lhs), BasicValueEnum::IntValue(rhs)) = (lhs, rhs) else {
-            unreachable!()
+            codegen_unreachable!(self)
         };
         let float = self.ctx.f64_type();
         match (op, signed) {
@@ -419,7 +420,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
                         .build_right_shift(lhs, rhs, signed, "rshift")
                         .map(Into::into)
                         .unwrap(),
-                    _ => unreachable!(),
+                    _ => codegen_unreachable!(self),
                 }
             }
 
@@ -431,7 +432,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
             }
             (Operator::Pow, s) => integer_power(generator, self, lhs, rhs, s).into(),
             // special implementation?
-            (Operator::MatMult, _) => unreachable!(),
+            (Operator::MatMult, _) => codegen_unreachable!(self),
         }
     }
 
@@ -443,7 +444,8 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
         rhs: BasicValueEnum<'ctx>,
     ) -> BasicValueEnum<'ctx> {
         let (BasicValueEnum::FloatValue(lhs), BasicValueEnum::FloatValue(rhs)) = (lhs, rhs) else {
-            unreachable!(
+            codegen_unreachable!(
+                self,
                 "Expected (FloatValue, FloatValue), got ({}, {})",
                 lhs.get_type(),
                 rhs.get_type()
@@ -687,7 +689,7 @@ pub fn gen_constructor<'ctx, 'a, G: CodeGenerator>(
     def: &TopLevelDef,
     params: Vec<(Option<StrRef>, ValueEnum<'ctx>)>,
 ) -> Result<BasicValueEnum<'ctx>, String> {
-    let TopLevelDef::Class { methods, .. } = def else { unreachable!() };
+    let TopLevelDef::Class { methods, .. } = def else { codegen_unreachable!(ctx) };
 
     // TODO: what about other fields that require alloca?
     let fun_id = methods.iter().find(|method| method.0 == "__init__".into()).map(|method| method.2);
@@ -719,7 +721,7 @@ pub fn gen_func_instance<'ctx>(
         key,
     ) = fun
     else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     };
 
     if let Some(sym) = instance_to_symbol.get(&key) {
@@ -751,7 +753,7 @@ pub fn gen_func_instance<'ctx>(
         .collect();
 
     let mut signature = store.from_signature(&mut ctx.unifier, &ctx.primitives, sign, &mut cache);
-    let ConcreteTypeEnum::TFunc { args, .. } = &mut signature else { unreachable!() };
+    let ConcreteTypeEnum::TFunc { args, .. } = &mut signature else { codegen_unreachable!(ctx) };
 
     if let Some(obj) = &obj {
         let zelf = store.from_unifier_type(&mut ctx.unifier, &ctx.primitives, obj.0, &mut cache);
@@ -1117,7 +1119,7 @@ pub fn gen_comprehension<'ctx, G: CodeGenerator>(
     ctx: &mut CodeGenContext<'ctx, '_>,
     expr: &Expr<Option<Type>>,
 ) -> Result<Option<BasicValueEnum<'ctx>>, String> {
-    let ExprKind::ListComp { elt, generators } = &expr.node else { unreachable!() };
+    let ExprKind::ListComp { elt, generators } = &expr.node else { codegen_unreachable!(ctx) };
 
     let current = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
 
@@ -1376,13 +1378,13 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                     if let TypeEnum::TObj { params, .. } = &*ctx.unifier.get_ty_immutable(ty1) {
                         ctx.unifier.get_representative(*params.iter().next().unwrap().1)
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
                 let elem_ty2 =
                     if let TypeEnum::TObj { params, .. } = &*ctx.unifier.get_ty_immutable(ty2) {
                         ctx.unifier.get_representative(*params.iter().next().unwrap().1)
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
                 debug_assert!(ctx.unifier.unioned(elem_ty1, elem_ty2));
 
@@ -1455,7 +1457,7 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                         {
                             *params.iter().next().unwrap().1
                         } else {
-                            unreachable!()
+                            codegen_unreachable!(ctx)
                         };
 
                         (elem_ty, left_val, right_val)
@@ -1465,12 +1467,12 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
                         {
                             *params.iter().next().unwrap().1
                         } else {
-                            unreachable!()
+                            codegen_unreachable!(ctx)
                         };
 
                         (elem_ty, right_val, left_val)
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
                 let list_val =
                     ListValue::from_ptr_val(list_val.into_pointer_value(), llvm_usize, None);
@@ -1637,7 +1639,7 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
     } else {
         let left_ty_enum = ctx.unifier.get_ty_immutable(left_ty.unwrap());
         let TypeEnum::TObj { fields, obj_id, .. } = left_ty_enum.as_ref() else {
-            unreachable!("must be tobj")
+            codegen_unreachable!(ctx, "must be tobj")
         };
         let (op_name, id) = {
             let normal_method_name = Binop::normal(op.base).op_info().method_name;
@@ -1658,19 +1660,19 @@ pub fn gen_binop_expr_with_values<'ctx, G: CodeGenerator>(
         } else {
             let left_enum_ty = ctx.unifier.get_ty_immutable(left_ty.unwrap());
             let TypeEnum::TObj { fields, .. } = left_enum_ty.as_ref() else {
-                unreachable!("must be tobj")
+                codegen_unreachable!(ctx, "must be tobj")
             };
 
             let fn_ty = fields.get(&op_name).unwrap().0;
             let fn_ty_enum = ctx.unifier.get_ty_immutable(fn_ty);
-            let TypeEnum::TFunc(sig) = fn_ty_enum.as_ref() else { unreachable!() };
+            let TypeEnum::TFunc(sig) = fn_ty_enum.as_ref() else { codegen_unreachable!(ctx) };
 
             sig.clone()
         };
         let fun_id = {
             let defs = ctx.top_level.definitions.read();
             let obj_def = defs.get(id.0).unwrap().read();
-            let TopLevelDef::Class { methods, .. } = &*obj_def else { unreachable!() };
+            let TopLevelDef::Class { methods, .. } = &*obj_def else { codegen_unreachable!(ctx) };
 
             methods.iter().find(|method| method.0 == op_name).unwrap().2
         };
@@ -1801,7 +1803,8 @@ pub fn gen_unaryop_expr_with_values<'ctx, G: CodeGenerator>(
             if op == ast::Unaryop::Invert {
                 ast::Unaryop::Not
             } else {
-                unreachable!(
+                codegen_unreachable!(
+                    ctx,
                     "ufunc {} not supported for ndarray[bool, N]",
                     op.op_info().method_name,
                 )
@@ -1868,8 +1871,8 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
         {
             let llvm_usize = generator.get_size_type(ctx.ctx);
 
-            let (Some(left_ty), lhs) = left else { unreachable!() };
-            let (Some(right_ty), rhs) = comparators[0] else { unreachable!() };
+            let (Some(left_ty), lhs) = left else { codegen_unreachable!(ctx) };
+            let (Some(right_ty), rhs) = comparators[0] else { codegen_unreachable!(ctx) };
             let op = ops[0];
 
             let is_ndarray1 =
@@ -1976,7 +1979,7 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                 let op = match op {
                     ast::Cmpop::Eq | ast::Cmpop::Is => IntPredicate::EQ,
                     ast::Cmpop::NotEq => IntPredicate::NE,
-                    _ if left_ty == ctx.primitives.bool => unreachable!(),
+                    _ if left_ty == ctx.primitives.bool => codegen_unreachable!(ctx),
                     ast::Cmpop::Lt => {
                         if use_unsigned_ops {
                             IntPredicate::ULT
@@ -2005,7 +2008,7 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                             IntPredicate::SGE
                         }
                     }
-                    _ => unreachable!(),
+                    _ => codegen_unreachable!(ctx),
                 };
 
                 ctx.builder.build_int_compare(op, lhs, rhs, "cmp").unwrap()
@@ -2022,7 +2025,7 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                     ast::Cmpop::LtE => inkwell::FloatPredicate::OLE,
                     ast::Cmpop::Gt => inkwell::FloatPredicate::OGT,
                     ast::Cmpop::GtE => inkwell::FloatPredicate::OGE,
-                    _ => unreachable!(),
+                    _ => codegen_unreachable!(ctx),
                 };
                 ctx.builder.build_float_compare(op, lhs, rhs, "cmp").unwrap()
             } else if left_ty == ctx.primitives.str {
@@ -2154,7 +2157,7 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                         match (op, val) {
                             (Cmpop::Eq, true) | (Cmpop::NotEq, false) => llvm_i1.const_all_ones(),
                             (Cmpop::Eq, false) | (Cmpop::NotEq, true) => llvm_i1.const_zero(),
-                            (_, _) => unreachable!(),
+                            (_, _) => codegen_unreachable!(ctx),
                         }
                     };
 
@@ -2167,14 +2170,14 @@ pub fn gen_cmpop_expr_with_values<'ctx, G: CodeGenerator>(
                     {
                         *params.iter().next().unwrap().1
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
                     let right_elem_ty = if let TypeEnum::TObj { params, .. } =
                         &*ctx.unifier.get_ty_immutable(right_ty)
                     {
                         *params.iter().next().unwrap().1
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
 
                     if !ctx.unifier.unioned(left_elem_ty, right_elem_ty) {
@@ -2511,7 +2514,7 @@ fn gen_ndarray_subscript_expr<'ctx, G: CodeGenerator>(
     let llvm_usize = generator.get_size_type(ctx.ctx);
 
     let TypeEnum::TLiteral { values, .. } = &*ctx.unifier.get_ty_immutable(ndims) else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     };
 
     let ndims = values
@@ -2863,7 +2866,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         .const_null()
                         .into()
                 }
-                _ => unreachable!("must be option type"),
+                _ => codegen_unreachable!(ctx, "must be option type"),
             }
         }
         ExprKind::Name { id, .. } => match ctx.var_assignment.get(id) {
@@ -2924,7 +2927,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
 
                     *params.iter().next().unwrap().1
                 } else {
-                    unreachable!()
+                    codegen_unreachable!(ctx)
                 };
 
                 if let TypeEnum::TVar { .. } = &*ctx.unifier.get_ty_immutable(ty) {
@@ -3018,7 +3021,9 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
 
                             return generator.gen_expr(ctx, &modified_expr);
                         }
-                        None => unreachable!("Function Type should not have attributes"),
+                        None => {
+                            codegen_unreachable!(ctx, "Function Type should not have attributes")
+                        }
                     }
                 } else if let TypeEnum::TObj { obj_id, fields, params } = &*ctx.unifier.get_ty(c) {
                     if fields.is_empty() && params.is_empty() {
@@ -3040,7 +3045,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
 
                                 return generator.gen_expr(ctx, &modified_expr);
                             }
-                            None => unreachable!(),
+                            None => codegen_unreachable!(ctx),
                         }
                     }
                 }
@@ -3142,7 +3147,7 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                 }
                 (Some(a), None) => a.into(),
                 (None, Some(b)) => b.into(),
-                (None, None) => unreachable!(),
+                (None, None) => codegen_unreachable!(ctx),
             }
         }
         ExprKind::BinOp { op, left, right } => {
@@ -3232,7 +3237,9 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                 ctx.unifier.get_call_signature(*call).unwrap()
             } else {
                 let ty = func.custom.unwrap();
-                let TypeEnum::TFunc(sign) = &*ctx.unifier.get_ty(ty) else { unreachable!() };
+                let TypeEnum::TFunc(sign) = &*ctx.unifier.get_ty(ty) else {
+                    codegen_unreachable!(ctx)
+                };
 
                 sign.clone()
             };
@@ -3256,12 +3263,14 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                     {
                         *obj_id
                     } else {
-                        unreachable!()
+                        codegen_unreachable!(ctx)
                     };
                     let fun_id = {
                         let defs = ctx.top_level.definitions.read();
                         let obj_def = defs.get(id.0).unwrap().read();
-                        let TopLevelDef::Class { methods, .. } = &*obj_def else { unreachable!() };
+                        let TopLevelDef::Class { methods, .. } = &*obj_def else {
+                            codegen_unreachable!(ctx)
+                        };
 
                         methods.iter().find(|method| method.0 == *attr).unwrap().2
                     };
@@ -3332,7 +3341,9 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                                         .unwrap(),
                                 ));
                             }
-                            ValueEnum::Dynamic(_) => unreachable!("option must be static or ptr"),
+                            ValueEnum::Dynamic(_) => {
+                                codegen_unreachable!(ctx, "option must be static or ptr")
+                            }
                         }
                     }
 
@@ -3481,7 +3492,10 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         if let ExprKind::Constant { value: Constant::Int(v), .. } = &slice.node {
                             (*v).try_into().unwrap()
                         } else {
-                            unreachable!("tuple subscript must be const int after type check");
+                            codegen_unreachable!(
+                                ctx,
+                                "tuple subscript must be const int after type check"
+                            );
                         };
                     match generator.gen_expr(ctx, value)? {
                         Some(ValueEnum::Dynamic(v)) => {
@@ -3504,7 +3518,10 @@ pub fn gen_expr<'ctx, G: CodeGenerator>(
                         None => return Ok(None),
                     }
                 }
-                _ => unreachable!("should not be other subscriptable types after type check"),
+                _ => codegen_unreachable!(
+                    ctx,
+                    "should not be other subscriptable types after type check"
+                ),
             }
         }
         ExprKind::ListComp { .. } => {
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 91e62e94..0a809e18 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -3,12 +3,13 @@ use crate::typecheck::typedef::Type;
 use super::{
     classes::{
         ArrayLikeIndexer, ArrayLikeValue, ArraySliceValue, ListValue, NDArrayValue,
-        TypedArrayLikeAdapter, UntypedArrayLikeAccessor,
+        TypedArrayLikeAccessor, TypedArrayLikeAdapter, UntypedArrayLikeAccessor,
     },
-    llvm_intrinsics, CodeGenContext, CodeGenerator,
+    llvm_intrinsics,
+    macros::codegen_unreachable,
+    stmt::gen_for_callback_incrementing,
+    CodeGenContext, CodeGenerator,
 };
-use crate::codegen::classes::TypedArrayLikeAccessor;
-use crate::codegen::stmt::gen_for_callback_incrementing;
 use inkwell::{
     attributes::{Attribute, AttributeLoc},
     context::Context,
@@ -55,7 +56,7 @@ pub fn integer_power<'ctx, G: CodeGenerator + ?Sized>(
         (64, 64, true) => "__nac3_int_exp_int64_t",
         (32, 32, false) => "__nac3_int_exp_uint32_t",
         (64, 64, false) => "__nac3_int_exp_uint64_t",
-        _ => unreachable!(),
+        _ => codegen_unreachable!(ctx),
     };
     let base_type = base.get_type();
     let pow_fun = ctx.module.get_function(symbol).unwrap_or_else(|| {
@@ -441,7 +442,7 @@ pub fn list_slice_assignment<'ctx, G: CodeGenerator + ?Sized>(
                     BasicTypeEnum::IntType(t) => t.size_of(),
                     BasicTypeEnum::PointerType(t) => t.size_of(),
                     BasicTypeEnum::StructType(t) => t.size_of().unwrap(),
-                    _ => unreachable!(),
+                    _ => codegen_unreachable!(ctx),
                 };
                 ctx.builder.build_int_truncate_or_bit_cast(s, int32, "size").unwrap()
             }
@@ -586,7 +587,7 @@ where
     let ndarray_calc_size_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_calc_size",
         64 => "__nac3_ndarray_calc_size64",
-        bw => unreachable!("Unsupported size type bit width: {}", bw),
+        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
     };
     let ndarray_calc_size_fn_t = llvm_usize.fn_type(
         &[llvm_pusize.into(), llvm_usize.into(), llvm_usize.into(), llvm_usize.into()],
@@ -637,7 +638,7 @@ pub fn call_ndarray_calc_nd_indices<'ctx, G: CodeGenerator + ?Sized>(
     let ndarray_calc_nd_indices_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_calc_nd_indices",
         64 => "__nac3_ndarray_calc_nd_indices64",
-        bw => unreachable!("Unsupported size type bit width: {}", bw),
+        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
     };
     let ndarray_calc_nd_indices_fn =
         ctx.module.get_function(ndarray_calc_nd_indices_fn_name).unwrap_or_else(|| {
@@ -706,7 +707,7 @@ where
     let ndarray_flatten_index_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_flatten_index",
         64 => "__nac3_ndarray_flatten_index64",
-        bw => unreachable!("Unsupported size type bit width: {}", bw),
+        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
     };
     let ndarray_flatten_index_fn =
         ctx.module.get_function(ndarray_flatten_index_fn_name).unwrap_or_else(|| {
@@ -774,7 +775,7 @@ pub fn call_ndarray_calc_broadcast<'ctx, G: CodeGenerator + ?Sized>(
     let ndarray_calc_broadcast_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_calc_broadcast",
         64 => "__nac3_ndarray_calc_broadcast64",
-        bw => unreachable!("Unsupported size type bit width: {}", bw),
+        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
     };
     let ndarray_calc_broadcast_fn =
         ctx.module.get_function(ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
@@ -894,7 +895,7 @@ pub fn call_ndarray_calc_broadcast_index<
     let ndarray_calc_broadcast_fn_name = match llvm_usize.get_bit_width() {
         32 => "__nac3_ndarray_calc_broadcast_idx",
         64 => "__nac3_ndarray_calc_broadcast_idx64",
-        bw => unreachable!("Unsupported size type bit width: {}", bw),
+        bw => codegen_unreachable!(ctx, "Unsupported size type bit width: {}", bw),
     };
     let ndarray_calc_broadcast_fn =
         ctx.module.get_function(ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 71a2d52a..eecf5c2e 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -50,6 +50,22 @@ mod test;
 use concrete_type::{ConcreteType, ConcreteTypeEnum, ConcreteTypeStore};
 pub use generator::{CodeGenerator, DefaultCodeGenerator};
 
+mod macros {
+    /// Codegen-variant of [`std::unreachable`] which accepts an instance of [`CodeGenContext`] as
+    /// its first argument to provide Python source information to indicate the codegen location
+    /// causing the assertion.
+    macro_rules! codegen_unreachable {
+        ($ctx:expr $(,)?) => {
+            std::unreachable!("unreachable code while processing {}", &$ctx.current_loc)
+        };
+        ($ctx:expr, $($arg:tt)*) => {
+            std::unreachable!("unreachable code while processing {}: {}", &$ctx.current_loc, std::format!("{}", std::format_args!($($arg)+)))
+        };
+    }
+
+    pub(crate) use codegen_unreachable;
+}
+
 #[derive(Default)]
 pub struct StaticValueStore {
     pub lookup: HashMap<Vec<(usize, u64)>, usize>,
diff --git a/nac3core/src/codegen/numpy.rs b/nac3core/src/codegen/numpy.rs
index d58b566b..41dad1f3 100644
--- a/nac3core/src/codegen/numpy.rs
+++ b/nac3core/src/codegen/numpy.rs
@@ -12,6 +12,7 @@ use crate::{
             call_ndarray_calc_size,
         },
         llvm_intrinsics::{self, call_memcpy_generic},
+        macros::codegen_unreachable,
         stmt::{gen_for_callback_incrementing, gen_for_range_callback, gen_if_else_expr_callback},
         CodeGenContext, CodeGenerator,
     },
@@ -259,7 +260,7 @@ fn ndarray_zero_value<'ctx, G: CodeGenerator + ?Sized>(
     } else if ctx.unifier.unioned(elem_ty, ctx.primitives.str) {
         ctx.gen_string(generator, "").into()
     } else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     }
 }
 
@@ -287,7 +288,7 @@ fn ndarray_one_value<'ctx, G: CodeGenerator + ?Sized>(
     } else if ctx.unifier.unioned(elem_ty, ctx.primitives.str) {
         ctx.gen_string(generator, "1").into()
     } else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     }
 }
 
@@ -355,7 +356,7 @@ fn call_ndarray_empty_impl<'ctx, G: CodeGenerator + ?Sized>(
 
             create_ndarray_const_shape(generator, ctx, elem_ty, &[shape_int])
         }
-        _ => unreachable!(),
+        _ => codegen_unreachable!(ctx),
     }
 }
 
@@ -626,7 +627,7 @@ fn call_ndarray_full_impl<'ctx, G: CodeGenerator + ?Sized>(
         } else if fill_value.is_int_value() || fill_value.is_float_value() {
             fill_value
         } else {
-            unreachable!()
+            codegen_unreachable!(ctx)
         };
 
         Ok(value)
@@ -2020,7 +2021,7 @@ pub fn gen_ndarray_fill<'ctx>(
             } else if value_arg.is_int_value() || value_arg.is_float_value() {
                 value_arg
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
 
             Ok(value)
@@ -2129,7 +2130,8 @@ pub fn ndarray_transpose<'ctx, G: CodeGenerator + ?Sized>(
 
         Ok(out.as_base_value().into())
     } else {
-        unreachable!(
+        codegen_unreachable!(
+            ctx,
             "{FN_NAME}() not supported for '{}'",
             format!("'{}'", ctx.unifier.stringify(x1_ty))
         )
@@ -2371,7 +2373,7 @@ pub fn ndarray_reshape<'ctx, G: CodeGenerator + ?Sized>(
                 .into_int_value();
                 create_ndarray_const_shape(generator, ctx, elem_ty, &[shape_int])
             }
-            _ => unreachable!(),
+            _ => codegen_unreachable!(ctx),
         }
         .unwrap();
 
@@ -2415,7 +2417,8 @@ pub fn ndarray_reshape<'ctx, G: CodeGenerator + ?Sized>(
 
         Ok(out.as_base_value().into())
     } else {
-        unreachable!(
+        codegen_unreachable!(
+            ctx,
             "{FN_NAME}() not supported for '{}'",
             format!("'{}'", ctx.unifier.stringify(x1_ty))
         )
@@ -2483,7 +2486,7 @@ pub fn ndarray_dot<'ctx, G: CodeGenerator + ?Sized>(
                             .build_float_mul(e1, elem2.into_float_value(), "")
                             .unwrap()
                             .as_basic_value_enum(),
-                        _ => unreachable!(),
+                        _ => codegen_unreachable!(ctx),
                     };
                     let acc_val = ctx.builder.build_load(acc, "").unwrap();
                     let acc_val = match acc_val {
@@ -2497,7 +2500,7 @@ pub fn ndarray_dot<'ctx, G: CodeGenerator + ?Sized>(
                             .build_float_add(e1, product.into_float_value(), "")
                             .unwrap()
                             .as_basic_value_enum(),
-                        _ => unreachable!(),
+                        _ => codegen_unreachable!(ctx),
                     };
                     ctx.builder.build_store(acc, acc_val).unwrap();
 
@@ -2514,7 +2517,8 @@ pub fn ndarray_dot<'ctx, G: CodeGenerator + ?Sized>(
         (BasicValueEnum::FloatValue(e1), BasicValueEnum::FloatValue(e2)) => {
             Ok(ctx.builder.build_float_mul(e1, e2, "").unwrap().as_basic_value_enum())
         }
-        _ => unreachable!(
+        _ => codegen_unreachable!(
+            ctx,
             "{FN_NAME}() not supported for '{}'",
             format!("'{}'", ctx.unifier.stringify(x1_ty))
         ),
diff --git a/nac3core/src/codegen/stmt.rs b/nac3core/src/codegen/stmt.rs
index 081a5cef..da4b6ee0 100644
--- a/nac3core/src/codegen/stmt.rs
+++ b/nac3core/src/codegen/stmt.rs
@@ -1,15 +1,13 @@
 use super::{
-    super::symbol_resolver::ValueEnum,
-    expr::destructure_range,
+    classes::{ArrayLikeIndexer, ArraySliceValue, ListValue, RangeValue},
+    expr::{destructure_range, gen_binop_expr},
+    gen_in_range_check,
     irrt::{handle_slice_indices, list_slice_assignment},
+    macros::codegen_unreachable,
     CodeGenContext, CodeGenerator,
 };
 use crate::{
-    codegen::{
-        classes::{ArrayLikeIndexer, ArraySliceValue, ListValue, RangeValue},
-        expr::gen_binop_expr,
-        gen_in_range_check,
-    },
+    symbol_resolver::ValueEnum,
     toplevel::{DefinitionId, TopLevelDef},
     typecheck::{
         magic_methods::Binop,
@@ -121,7 +119,7 @@ pub fn gen_store_target<'ctx, G: CodeGenerator>(
                 return Ok(None);
             };
             let BasicValueEnum::PointerValue(ptr) = val else {
-                unreachable!();
+                codegen_unreachable!(ctx);
             };
             unsafe {
                 ctx.builder.build_in_bounds_gep(
@@ -135,7 +133,7 @@ pub fn gen_store_target<'ctx, G: CodeGenerator>(
             }
             .unwrap()
         }
-        _ => unreachable!(),
+        _ => codegen_unreachable!(ctx),
     }))
 }
 
@@ -193,12 +191,12 @@ pub fn gen_assign_target_list<'ctx, G: CodeGenerator>(
     // Deconstruct the tuple `value`
     let BasicValueEnum::StructValue(tuple) = value.to_basic_value_enum(ctx, generator, value_ty)?
     else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     };
 
     // NOTE: Currently, RHS's type is forced to be a Tuple by the type inferencer.
     let TypeEnum::TTuple { ty: tuple_tys, .. } = &*ctx.unifier.get_ty(value_ty) else {
-        unreachable!();
+        codegen_unreachable!(ctx);
     };
 
     assert_eq!(tuple.get_type().count_fields() as usize, tuple_tys.len());
@@ -258,7 +256,7 @@ pub fn gen_assign_target_list<'ctx, G: CodeGenerator>(
             // Now assign with that sub-tuple to the starred target.
             generator.gen_assign(ctx, target, ValueEnum::Dynamic(sub_tuple_val), sub_tuple_ty)?;
         } else {
-            unreachable!() // The typechecker ensures this
+            codegen_unreachable!(ctx) // The typechecker ensures this
         }
 
         // Handle assignment after the starred target
@@ -306,7 +304,9 @@ pub fn gen_setitem<'ctx, G: CodeGenerator>(
 
             if let ExprKind::Slice { .. } = &key.node {
                 // Handle assigning to a slice
-                let ExprKind::Slice { lower, upper, step } = &key.node else { unreachable!() };
+                let ExprKind::Slice { lower, upper, step } = &key.node else {
+                    codegen_unreachable!(ctx)
+                };
                 let Some((start, end, step)) = handle_slice_indices(
                     lower,
                     upper,
@@ -416,7 +416,9 @@ pub fn gen_for<G: CodeGenerator>(
     ctx: &mut CodeGenContext<'_, '_>,
     stmt: &Stmt<Option<Type>>,
 ) -> Result<(), String> {
-    let StmtKind::For { iter, target, body, orelse, .. } = &stmt.node else { unreachable!() };
+    let StmtKind::For { iter, target, body, orelse, .. } = &stmt.node else {
+        codegen_unreachable!(ctx)
+    };
 
     // var_assignment static values may be changed in another branch
     // if so, remove the static value as it may not be correct in this branch
@@ -458,7 +460,7 @@ pub fn gen_for<G: CodeGenerator>(
             let Some(target_i) =
                 generator.gen_store_target(ctx, target, Some("for.target.addr"))?
             else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
             let (start, stop, step) = destructure_range(ctx, iter_val);
 
@@ -901,7 +903,7 @@ pub fn gen_while<G: CodeGenerator>(
     ctx: &mut CodeGenContext<'_, '_>,
     stmt: &Stmt<Option<Type>>,
 ) -> Result<(), String> {
-    let StmtKind::While { test, body, orelse, .. } = &stmt.node else { unreachable!() };
+    let StmtKind::While { test, body, orelse, .. } = &stmt.node else { codegen_unreachable!(ctx) };
 
     // var_assignment static values may be changed in another branch
     // if so, remove the static value as it may not be correct in this branch
@@ -931,7 +933,7 @@ pub fn gen_while<G: CodeGenerator>(
 
         return Ok(());
     };
-    let BasicValueEnum::IntValue(test) = test else { unreachable!() };
+    let BasicValueEnum::IntValue(test) = test else { codegen_unreachable!(ctx) };
 
     ctx.builder
         .build_conditional_branch(generator.bool_to_i1(ctx, test), body_bb, orelse_bb)
@@ -1079,7 +1081,7 @@ pub fn gen_if<G: CodeGenerator>(
     ctx: &mut CodeGenContext<'_, '_>,
     stmt: &Stmt<Option<Type>>,
 ) -> Result<(), String> {
-    let StmtKind::If { test, body, orelse, .. } = &stmt.node else { unreachable!() };
+    let StmtKind::If { test, body, orelse, .. } = &stmt.node else { codegen_unreachable!(ctx) };
 
     // var_assignment static values may be changed in another branch
     // if so, remove the static value as it may not be correct in this branch
@@ -1202,11 +1204,11 @@ pub fn exn_constructor<'ctx>(
     let zelf_id = if let TypeEnum::TObj { obj_id, .. } = &*ctx.unifier.get_ty(zelf_ty) {
         obj_id.0
     } else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     };
     let defs = ctx.top_level.definitions.read();
     let def = defs[zelf_id].read();
-    let TopLevelDef::Class { name: zelf_name, .. } = &*def else { unreachable!() };
+    let TopLevelDef::Class { name: zelf_name, .. } = &*def else { codegen_unreachable!(ctx) };
     let exception_name = format!("{}:{}", ctx.resolver.get_exception_id(zelf_id), zelf_name);
     unsafe {
         let id_ptr = ctx.builder.build_in_bounds_gep(zelf, &[zero, zero], "exn.id").unwrap();
@@ -1314,7 +1316,7 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
     target: &Stmt<Option<Type>>,
 ) -> Result<(), String> {
     let StmtKind::Try { body, handlers, orelse, finalbody, .. } = &target.node else {
-        unreachable!()
+        codegen_unreachable!(ctx)
     };
 
     // if we need to generate anything related to exception, we must have personality defined
@@ -1391,7 +1393,7 @@ pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
             if let TypeEnum::TObj { obj_id, .. } = &*ctx.unifier.get_ty(type_.custom.unwrap()) {
                 *obj_id
             } else {
-                unreachable!()
+                codegen_unreachable!(ctx)
             };
         let exception_name = format!("{}:{}", ctx.resolver.get_exception_id(obj_id.0), exn_name);
         let exn_id = ctx.resolver.get_string_id(&exception_name);