Sema: introduce a type resolution queue

That happens after a function body is analyzed. This prevents circular
dependency compile errors and yet a way to mark types that need to be
fully resolved before a given function is sent to the codegen backend.

5 files changed, 82 insertions, 44 deletions

diff --git a/src/Air.zig b/src/Air.zig
index e0f765ddc0..404ee8f9b7 100644
--- a/src/Air.zig
+++ b/src/Air.zig
@@ -1072,7 +1072,7 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         .sub_with_overflow,
         .mul_with_overflow,
         .shl_with_overflow,
-        => return Type.initTag(.bool),
+        => return Type.bool,
     }
 }
 
diff --git a/src/Module.zig b/src/Module.zig
index 7b27546f52..79d6343949 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -4837,6 +4837,9 @@ pub fn analyzeFnBody(mod: *Module, decl: *Decl, func: *Fn, arena: Allocator) Sem
 
     // Finally we must resolve the return type and parameter types so that backends
     // have full access to type information.
+    // Crucially, this happens *after* we set the function state to success above,
+    // so that dependencies on the function body will now be satisfied rather than
+    // result in circular dependency errors.
     const src: LazySrcLoc = .{ .node_offset = 0 };
     sema.resolveFnTypes(&inner_block, src, fn_ty_info) catch |err| switch (err) {
         error.NeededSourceLocation => unreachable,
@@ -4847,6 +4850,20 @@ pub fn analyzeFnBody(mod: *Module, decl: *Decl, func: *Fn, arena: Allocator) Sem
         else => |e| return e,
     };
 
+    // Similarly, resolve any queued up types that were requested to be resolved for
+    // the backends.
+    for (sema.types_to_resolve.items) |inst_ref| {
+        const ty = sema.getTmpAir().getRefType(inst_ref);
+        sema.resolveTypeFully(&inner_block, src, ty) catch |err| switch (err) {
+            error.NeededSourceLocation => unreachable,
+            error.GenericPoison => unreachable,
+            error.ComptimeReturn => unreachable,
+            error.ComptimeBreak => unreachable,
+            error.AnalysisFail => {},
+            else => |e| return e,
+        };
+    }
+
     return Air{
         .instructions = sema.air_instructions.toOwnedSlice(),
         .extra = sema.air_extra.toOwnedSlice(gpa),
diff --git a/src/Sema.zig b/src/Sema.zig
index 7e87ebbf33..d8cc908ae8 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -63,6 +63,11 @@ comptime_args_fn_inst: Zir.Inst.Index = 0,
 /// extra hash table lookup in the `monomorphed_funcs` set.
 /// Sema will set this to null when it takes ownership.
 preallocated_new_func: ?*Module.Fn = null,
+/// The key is `constant` AIR instructions to types that must be fully resolved
+/// after the current function body analysis is done.
+/// TODO: after upgrading to use InternPool change the key here to be an
+/// InternPool value index.
+types_to_resolve: std.ArrayListUnmanaged(Air.Inst.Ref) = .{},
 
 const std = @import("std");
 const mem = std.mem;
@@ -527,6 +532,7 @@ pub fn deinit(sema: *Sema) void {
     sema.air_values.deinit(gpa);
     sema.inst_map.deinit(gpa);
     sema.decl_val_table.deinit(gpa);
+    sema.types_to_resolve.deinit(gpa);
     sema.* = undefined;
 }
 
@@ -1747,7 +1753,7 @@ fn zirCoerceResultPtr(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileE
                     return sema.bitCast(block, ptr_ty, new_ptr, src);
                 }
                 const ty_op = air_datas[trash_inst].ty_op;
-                const operand_ty = sema.getTmpAir().typeOf(ty_op.operand);
+                const operand_ty = sema.typeOf(ty_op.operand);
                 const ptr_operand_ty = try Type.ptr(sema.arena, target, .{
                     .pointee_type = operand_ty,
                     .@"addrspace" = addr_space,
@@ -2592,7 +2598,7 @@ fn zirAlloc(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air.I
         .@"addrspace" = target_util.defaultAddressSpace(target, .local),
     });
     try sema.requireRuntimeBlock(block, var_decl_src);
-    try sema.resolveTypeFully(block, ty_src, var_ty);
+    try sema.queueFullTypeResolution(var_ty);
     return block.addTy(.alloc, ptr_type);
 }
 
@@ -2614,7 +2620,7 @@ fn zirAllocMut(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Ai
         .@"addrspace" = target_util.defaultAddressSpace(target, .local),
     });
     try sema.requireRuntimeBlock(block, var_decl_src);
-    try sema.resolveTypeFully(block, ty_src, var_ty);
+    try sema.queueFullTypeResolution(var_ty);
     return block.addTy(.alloc, ptr_type);
 }
 
@@ -2770,7 +2776,7 @@ fn zirResolveInferredAlloc(sema: *Sema, block: *Block, inst: Zir.Inst.Index) Com
             }
 
             try sema.requireRuntimeBlock(block, src);
-            try sema.resolveTypeFully(block, ty_src, final_elem_ty);
+            try sema.queueFullTypeResolution(final_elem_ty);
 
             // Change it to a normal alloc.
             sema.air_instructions.set(ptr_inst, .{
@@ -4363,6 +4369,8 @@ fn addDbgVar(
         else => unreachable,
     }
 
+    try sema.queueFullTypeResolution(operand_ty);
+
     // Add the name to the AIR.
     const name_extra_index = @intCast(u32, sema.air_extra.items.len);
     const elements_used = name.len / 4 + 1;
@@ -5004,7 +5012,7 @@ fn analyzeCall(
             }
         }
 
-        try sema.resolveTypeFully(block, call_src, func_ty_info.return_type);
+        try sema.queueFullTypeResolution(func_ty_info.return_type);
 
         try sema.air_extra.ensureUnusedCapacity(gpa, @typeInfo(Air.Call).Struct.fields.len +
             args.len);
@@ -5344,7 +5352,7 @@ fn instantiateGenericCall(
             total_i += 1;
         }
 
-        try sema.resolveTypeFully(block, call_src, new_fn_info.return_type);
+        try sema.queueFullTypeResolution(new_fn_info.return_type);
     }
     try sema.air_extra.ensureUnusedCapacity(sema.gpa, @typeInfo(Air.Call).Struct.fields.len +
         runtime_args_len);
@@ -12030,7 +12038,8 @@ fn unionInit(
     }
 
     try sema.requireRuntimeBlock(block, init_src);
-    try sema.resolveTypeLayout(block, union_ty_src, union_ty);
+    _ = union_ty_src;
+    try sema.queueFullTypeResolution(union_ty);
     return block.addUnionInit(union_ty, field_index, init);
 }
 
@@ -12205,6 +12214,7 @@ fn finishStructInit(
     }
 
     try sema.requireRuntimeBlock(block, src);
+    try sema.queueFullTypeResolution(struct_ty);
     return block.addAggregateInit(struct_ty, field_inits);
 }
 
@@ -12351,7 +12361,7 @@ fn zirArrayInit(
     };
 
     try sema.requireRuntimeBlock(block, runtime_src);
-    try sema.resolveTypeLayout(block, src, elem_ty);
+    try sema.queueFullTypeResolution(elem_ty);
 
     if (is_ref) {
         const target = sema.mod.getTarget();
@@ -18339,7 +18349,7 @@ fn storePtr2(
     // TODO handle if the element type requires comptime
 
     try sema.requireRuntimeBlock(block, runtime_src);
-    try sema.resolveTypeLayout(block, src, elem_ty);
+    try sema.queueFullTypeResolution(elem_ty);
     _ = try block.addBinOp(air_tag, ptr, operand);
 }
 
@@ -21907,7 +21917,7 @@ fn typeOf(sema: *Sema, inst: Air.Inst.Ref) Type {
     return sema.getTmpAir().typeOf(inst);
 }
 
-fn getTmpAir(sema: Sema) Air {
+pub fn getTmpAir(sema: Sema) Air {
     return .{
         .instructions = sema.air_instructions.slice(),
         .extra = sema.air_extra.items,
@@ -22572,3 +22582,8 @@ fn anonStructFieldIndex(
 fn kit(sema: *Sema, block: *Block, src: LazySrcLoc) Module.WipAnalysis {
     return .{ .sema = sema, .block = block, .src = src };
 }
+
+fn queueFullTypeResolution(sema: *Sema, ty: Type) !void {
+    const inst_ref = try sema.addType(ty);
+    try sema.types_to_resolve.append(sema.gpa, inst_ref);
+}
diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index eb8d72a994..f2979d96b1 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -632,7 +632,7 @@ fn resolveInst(self: *Self, ref: Air.Inst.Ref) InnerError!WValue {
     // means we must generate it from a constant.
     const val = self.air.value(ref).?;
     const ty = self.air.typeOf(ref);
-    if (!ty.hasRuntimeBits() and !ty.isInt()) {
+    if (!ty.hasRuntimeBitsIgnoreComptime() and !ty.isInt()) {
         gop.value_ptr.* = WValue{ .none = {} };
         return gop.value_ptr.*;
     }
@@ -805,13 +805,13 @@ fn genFunctype(gpa: Allocator, fn_ty: Type, target: std.Target) !wasm.Type {
         defer gpa.free(fn_params);
         fn_ty.fnParamTypes(fn_params);
         for (fn_params) |param_type| {
-            if (!param_type.hasRuntimeBits()) continue;
+            if (!param_type.hasRuntimeBitsIgnoreComptime()) continue;
             try params.append(typeToValtype(param_type, target));
         }
     }
 
     // return type
-    if (!want_sret and return_type.hasRuntimeBits()) {
+    if (!want_sret and return_type.hasRuntimeBitsIgnoreComptime()) {
         try returns.append(typeToValtype(return_type, target));
     }
 
@@ -970,7 +970,7 @@ fn resolveCallingConventionValues(self: *Self, fn_ty: Type) InnerError!CallWValu
         .Naked => return result,
         .Unspecified, .C => {
             for (param_types) |ty| {
-                if (!ty.hasRuntimeBits()) {
+                if (!ty.hasRuntimeBitsIgnoreComptime()) {
                     continue;
                 }
 
@@ -1015,7 +1015,7 @@ fn restoreStackPointer(self: *Self) !void {
 ///
 /// Asserts Type has codegenbits
 fn allocStack(self: *Self, ty: Type) !WValue {
-    assert(ty.hasRuntimeBits());
+    assert(ty.hasRuntimeBitsIgnoreComptime());
     if (self.initial_stack_value == .none) {
         try self.initializeStack();
     }
@@ -1049,7 +1049,7 @@ fn allocStackPtr(self: *Self, inst: Air.Inst.Index) !WValue {
         try self.initializeStack();
     }
 
-    if (!pointee_ty.hasRuntimeBits()) {
+    if (!pointee_ty.hasRuntimeBitsIgnoreComptime()) {
         return self.allocStack(Type.usize); // create a value containing just the stack pointer.
     }
 
@@ -1235,18 +1235,18 @@ fn isByRef(ty: Type, target: std.Target) bool {
         .Struct,
         .Frame,
         .Union,
-        => return ty.hasRuntimeBits(),
+        => return ty.hasRuntimeBitsIgnoreComptime(),
         .Int => return if (ty.intInfo(target).bits > 64) true else false,
         .ErrorUnion => {
-            const has_tag = ty.errorUnionSet().hasRuntimeBits();
-            const has_pl = ty.errorUnionPayload().hasRuntimeBits();
+            const has_tag = ty.errorUnionSet().hasRuntimeBitsIgnoreComptime();
+            const has_pl = ty.errorUnionPayload().hasRuntimeBitsIgnoreComptime();
             if (!has_tag or !has_pl) return false;
-            return ty.hasRuntimeBits();
+            return ty.hasRuntimeBitsIgnoreComptime();
         },
         .Optional => {
             if (ty.isPtrLikeOptional()) return false;
             var buf: Type.Payload.ElemType = undefined;
-            return ty.optionalChild(&buf).hasRuntimeBits();
+            return ty.optionalChild(&buf).hasRuntimeBitsIgnoreComptime();
         },
         .Pointer => {
             // Slices act like struct and will be passed by reference
@@ -1511,7 +1511,7 @@ fn airRetLoad(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const un_op = self.air.instructions.items(.data)[inst].un_op;
     const operand = try self.resolveInst(un_op);
     const ret_ty = self.air.typeOf(un_op).childType();
-    if (!ret_ty.hasRuntimeBits()) return WValue.none;
+    if (!ret_ty.hasRuntimeBitsIgnoreComptime()) return WValue.none;
 
     if (!isByRef(ret_ty, self.target)) {
         const result = try self.load(operand, ret_ty, 0);
@@ -1567,7 +1567,7 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallOptions.
         const arg_val = try self.resolveInst(arg_ref);
 
         const arg_ty = self.air.typeOf(arg_ref);
-        if (!arg_ty.hasRuntimeBits()) continue;
+        if (!arg_ty.hasRuntimeBitsIgnoreComptime()) continue;
 
         switch (arg_val) {
             .stack_offset => try self.emitWValue(try self.buildPointerOffset(arg_val, 0, .new)),
@@ -1591,7 +1591,7 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallOptions.
         try self.addLabel(.call_indirect, fn_type_index);
     }
 
-    if (self.liveness.isUnused(inst) or !ret_ty.hasRuntimeBits()) {
+    if (self.liveness.isUnused(inst) or !ret_ty.hasRuntimeBitsIgnoreComptime()) {
         return WValue.none;
     } else if (ret_ty.isNoReturn()) {
         try self.addTag(.@"unreachable");
@@ -1625,7 +1625,7 @@ fn store(self: *Self, lhs: WValue, rhs: WValue, ty: Type, offset: u32) InnerErro
         .ErrorUnion => {
             const err_ty = ty.errorUnionSet();
             const pl_ty = ty.errorUnionPayload();
-            if (!pl_ty.hasRuntimeBits()) {
+            if (!pl_ty.hasRuntimeBitsIgnoreComptime()) {
                 return self.store(lhs, rhs, err_ty, 0);
             }
 
@@ -1638,7 +1638,7 @@ fn store(self: *Self, lhs: WValue, rhs: WValue, ty: Type, offset: u32) InnerErro
             }
             var buf: Type.Payload.ElemType = undefined;
             const pl_ty = ty.optionalChild(&buf);
-            if (!pl_ty.hasRuntimeBits()) {
+            if (!pl_ty.hasRuntimeBitsIgnoreComptime()) {
                 return self.store(lhs, rhs, Type.u8, 0);
             }
 
@@ -1696,7 +1696,7 @@ fn airLoad(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const operand = try self.resolveInst(ty_op.operand);
     const ty = self.air.getRefType(ty_op.ty);
 
-    if (!ty.hasRuntimeBits()) return WValue{ .none = {} };
+    if (!ty.hasRuntimeBitsIgnoreComptime()) return WValue{ .none = {} };
 
     if (isByRef(ty, self.target)) {
         const new_local = try self.allocStack(ty);
@@ -2200,7 +2200,7 @@ fn airCmp(self: *Self, inst: Air.Inst.Index, op: std.math.CompareOperator) Inner
     if (operand_ty.zigTypeTag() == .Optional and !operand_ty.isPtrLikeOptional()) {
         var buf: Type.Payload.ElemType = undefined;
         const payload_ty = operand_ty.optionalChild(&buf);
-        if (payload_ty.hasRuntimeBits()) {
+        if (payload_ty.hasRuntimeBitsIgnoreComptime()) {
             // When we hit this case, we must check the value of optionals
             // that are not pointers. This means first checking against non-null for
             // both lhs and rhs, as well as checking the payload are matching of lhs and rhs
@@ -2257,7 +2257,7 @@ fn airBr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const block = self.blocks.get(br.block_inst).?;
 
     // if operand has codegen bits we should break with a value
-    if (self.air.typeOf(br.operand).hasRuntimeBits()) {
+    if (self.air.typeOf(br.operand).hasRuntimeBitsIgnoreComptime()) {
         const operand = try self.resolveInst(br.operand);
         const op = switch (operand) {
             .stack_offset => try self.buildPointerOffset(operand, 0, .new),
@@ -2357,7 +2357,7 @@ fn airStructFieldVal(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const operand = try self.resolveInst(struct_field.struct_operand);
     const field_index = struct_field.field_index;
     const field_ty = struct_ty.structFieldType(field_index);
-    if (!field_ty.hasRuntimeBits()) return WValue{ .none = {} };
+    if (!field_ty.hasRuntimeBitsIgnoreComptime()) return WValue{ .none = {} };
     const offset = std.math.cast(u32, struct_ty.structFieldOffset(field_index, self.target)) catch {
         return self.fail("Field type '{}' too big to fit into stack frame", .{field_ty.fmt(self.target)});
     };
@@ -2544,7 +2544,7 @@ fn airIsErr(self: *Self, inst: Air.Inst.Index, opcode: wasm.Opcode) InnerError!W
 
     // load the error tag value
     try self.emitWValue(operand);
-    if (pl_ty.hasRuntimeBits()) {
+    if (pl_ty.hasRuntimeBitsIgnoreComptime()) {
         try self.addMemArg(.i32_load16_u, .{
             .offset = operand.offset(),
             .alignment = err_ty.errorUnionSet().abiAlignment(self.target),
@@ -2567,7 +2567,7 @@ fn airUnwrapErrUnionPayload(self: *Self, inst: Air.Inst.Index, op_is_ptr: bool)
     const op_ty = self.air.typeOf(ty_op.operand);
     const err_ty = if (op_is_ptr) op_ty.childType() else op_ty;
     const payload_ty = err_ty.errorUnionPayload();
-    if (!payload_ty.hasRuntimeBits()) return WValue{ .none = {} };
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime()) return WValue{ .none = {} };
     const err_align = err_ty.abiAlignment(self.target);
     const set_size = err_ty.errorUnionSet().abiSize(self.target);
     const offset = mem.alignForwardGeneric(u64, set_size, err_align);
@@ -2585,7 +2585,7 @@ fn airUnwrapErrUnionError(self: *Self, inst: Air.Inst.Index, op_is_ptr: bool) In
     const op_ty = self.air.typeOf(ty_op.operand);
     const err_ty = if (op_is_ptr) op_ty.childType() else op_ty;
     const payload_ty = err_ty.errorUnionPayload();
-    if (op_is_ptr or !payload_ty.hasRuntimeBits()) {
+    if (op_is_ptr or !payload_ty.hasRuntimeBitsIgnoreComptime()) {
         return operand;
     }
 
@@ -2599,7 +2599,7 @@ fn airWrapErrUnionPayload(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const operand = try self.resolveInst(ty_op.operand);
 
     const op_ty = self.air.typeOf(ty_op.operand);
-    if (!op_ty.hasRuntimeBits()) return operand;
+    if (!op_ty.hasRuntimeBitsIgnoreComptime()) return operand;
     const err_ty = self.air.getRefType(ty_op.ty);
     const err_align = err_ty.abiAlignment(self.target);
     const set_size = err_ty.errorUnionSet().abiSize(self.target);
@@ -2624,7 +2624,7 @@ fn airWrapErrUnionErr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const operand = try self.resolveInst(ty_op.operand);
     const err_ty = self.air.getRefType(ty_op.ty);
 
-    if (!err_ty.errorUnionPayload().hasRuntimeBits()) return operand;
+    if (!err_ty.errorUnionPayload().hasRuntimeBitsIgnoreComptime()) return operand;
 
     const err_union = try self.allocStack(err_ty);
     try self.store(err_union, operand, err_ty.errorUnionSet(), 0);
@@ -2690,7 +2690,7 @@ fn isNull(self: *Self, operand: WValue, optional_ty: Type, opcode: wasm.Opcode)
         const payload_ty = optional_ty.optionalChild(&buf);
         // When payload is zero-bits, we can treat operand as a value, rather than
         // a pointer to the stack value
-        if (payload_ty.hasRuntimeBits()) {
+        if (payload_ty.hasRuntimeBitsIgnoreComptime()) {
             try self.addMemArg(.i32_load8_u, .{ .offset = operand.offset(), .alignment = 1 });
         }
     }
@@ -2710,7 +2710,7 @@ fn airOptionalPayload(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const operand = try self.resolveInst(ty_op.operand);
     const opt_ty = self.air.typeOf(ty_op.operand);
     const payload_ty = self.air.typeOfIndex(inst);
-    if (!payload_ty.hasRuntimeBits()) return WValue{ .none = {} };
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime()) return WValue{ .none = {} };
     if (opt_ty.isPtrLikeOptional()) return operand;
 
     const offset = opt_ty.abiSize(self.target) - payload_ty.abiSize(self.target);
@@ -2731,7 +2731,7 @@ fn airOptionalPayloadPtr(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
 
     var buf: Type.Payload.ElemType = undefined;
     const payload_ty = opt_ty.optionalChild(&buf);
-    if (!payload_ty.hasRuntimeBits() or opt_ty.isPtrLikeOptional()) {
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime() or opt_ty.isPtrLikeOptional()) {
         return operand;
     }
 
@@ -2745,7 +2745,7 @@ fn airOptionalPayloadPtrSet(self: *Self, inst: Air.Inst.Index) InnerError!WValue
     const opt_ty = self.air.typeOf(ty_op.operand).childType();
     var buf: Type.Payload.ElemType = undefined;
     const payload_ty = opt_ty.optionalChild(&buf);
-    if (!payload_ty.hasRuntimeBits()) {
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
         return self.fail("TODO: Implement OptionalPayloadPtrSet for optional with zero-sized type {}", .{payload_ty.fmtDebug()});
     }
 
@@ -2769,7 +2769,7 @@ fn airWrapOptional(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
 
     const ty_op = self.air.instructions.items(.data)[inst].ty_op;
     const payload_ty = self.air.typeOf(ty_op.operand);
-    if (!payload_ty.hasRuntimeBits()) {
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
         const non_null_bit = try self.allocStack(Type.initTag(.u1));
         try self.emitWValue(non_null_bit);
         try self.addImm32(1);
@@ -2958,7 +2958,7 @@ fn airArrayToSlice(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
     const slice_local = try self.allocStack(slice_ty);
 
     // store the array ptr in the slice
-    if (array_ty.hasRuntimeBits()) {
+    if (array_ty.hasRuntimeBitsIgnoreComptime()) {
         try self.store(slice_local, operand, Type.usize, 0);
     }
 
@@ -3408,7 +3408,7 @@ fn airWasmMemoryGrow(self: *Self, inst: Air.Inst.Index) !WValue {
 }
 
 fn cmpOptionals(self: *Self, lhs: WValue, rhs: WValue, operand_ty: Type, op: std.math.CompareOperator) InnerError!WValue {
-    assert(operand_ty.hasRuntimeBits());
+    assert(operand_ty.hasRuntimeBitsIgnoreComptime());
     assert(op == .eq or op == .neq);
     var buf: Type.Payload.ElemType = undefined;
     const payload_ty = operand_ty.optionalChild(&buf);
@@ -3575,7 +3575,7 @@ fn airErrUnionPayloadPtrSet(self: *Self, inst: Air.Inst.Index) InnerError!WValue
 
     if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
 
-    if (!payload_ty.hasRuntimeBits()) {
+    if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
         return operand;
     }
 
diff --git a/test/behavior/eval.zig b/test/behavior/eval.zig
index cbe6cfc296..2129512f96 100644
--- a/test/behavior/eval.zig
+++ b/test/behavior/eval.zig
@@ -853,3 +853,9 @@ test "comptime pointer load through elem_ptr" {
         assert(ptr[1].x == 2);
     }
 }
+
+test "debug variable type resolved through indirect zero-bit types" {
+    const T = struct { key: []void };
+    const slice: []const T = &[_]T{};
+    _ = slice;
+}