zig

commit 1e61e5f4041859859dc5b6f1936cccfd32e9c3a5 (tree)
parent f35a963ac5a2ea053801c37be1271153f35b7df1
Author: LemonBoy <thatlemon@gmail.com>
Date:   Thu,  2 Jan 2020 12:56:46 +0100

Don't ptrCast a result-location assignment to _

After #4010 doing `_ = @bitCast(...)` triggered a nonsensical compiler
error.

Diffstat:
M
src/ir.cpp
 | 
18
+++++++++++++++---
M
test/stage1/behavior/bitcast.zig
 | 
4
++++

2 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/src/ir.cpp b/src/ir.cpp
@@ -17394,11 +17394,23 @@ static IrInstruction *ir_resolve_result_raw(IrAnalyze *ira, IrInstruction *suspe
             }
             ZigType *parent_ptr_type = parent_result_loc->value->type;
             assert(parent_ptr_type->id == ZigTypeIdPointer);
-            if ((err = type_resolve(ira->codegen, parent_ptr_type->data.pointer.child_type,
-                            ResolveStatusAlignmentKnown)))
-            {
+            ZigType *child_type = parent_ptr_type->data.pointer.child_type;
+
+            bool has_bits;
+            if ((err = type_has_bits2(ira->codegen, child_type, &has_bits))) {
+                return ira->codegen->invalid_instruction;
+            }
+
+            // This happens when the bitCast result is assigned to _
+            if (!has_bits) {
+                assert(allow_discard);
+                return parent_result_loc;
+            }
+
+            if ((err = type_resolve(ira->codegen, child_type, ResolveStatusAlignmentKnown))) {
                 return ira->codegen->invalid_instruction;
             }
+
             uint64_t parent_ptr_align = get_ptr_align(ira->codegen, parent_ptr_type);
             if ((err = type_resolve(ira->codegen, value_type, ResolveStatusAlignmentKnown))) {
                 return ira->codegen->invalid_instruction;
diff --git a/test/stage1/behavior/bitcast.zig b/test/stage1/behavior/bitcast.zig
@@ -146,3 +146,7 @@ test "comptime bitcast used in expression has the correct type" {
     };
     expect(@bitCast(u8, Foo{ .value = 0xF }) == 0xf);
 }
+
+test "bitcast result to _" {
+    _ = @bitCast(u8, @as(i8, 1));
+}