From c1ee846c221a43b3bb3f9e427a2077b444435ec7 Mon Sep 17 00:00:00 2001
From: LemonBoy <thatlemon@gmail.com>
Date: Mon, 30 Dec 2019 17:05:50 +0100
Subject: [PATCH] Fix ptrCast of zero-sized type

Closes #2431
---
 src/ir.cpp              | 34 +++++++++++++++++-----------------
 test/compile_errors.zig | 10 ++++++++++
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/src/ir.cpp b/src/ir.cpp
index a862ff1068..c4331d74e3 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -26599,6 +26599,23 @@ static IrInstruction *ir_analyze_ptr_cast(IrAnalyze *ira, IrInstruction *source_
     if ((err = resolve_ptr_align(ira, dest_type, &dest_align_bytes)))
         return ira->codegen->invalid_instruction;
 
+    if ((err = type_resolve(ira->codegen, dest_type, ResolveStatusZeroBitsKnown)))
+        return ira->codegen->invalid_instruction;
+
+    if ((err = type_resolve(ira->codegen, src_type, ResolveStatusZeroBitsKnown)))
+        return ira->codegen->invalid_instruction;
+
+    if (type_has_bits(dest_type) && !type_has_bits(src_type)) {
+        ErrorMsg *msg = ir_add_error(ira, source_instr,
+            buf_sprintf("'%s' and '%s' do not have the same in-memory representation",
+                buf_ptr(&src_type->name), buf_ptr(&dest_type->name)));
+        add_error_note(ira->codegen, msg, ptr->source_node,
+                buf_sprintf("'%s' has no in-memory bits", buf_ptr(&src_type->name)));
+        add_error_note(ira->codegen, msg, dest_type_src->source_node,
+                buf_sprintf("'%s' has in-memory bits", buf_ptr(&dest_type->name)));
+        return ira->codegen->invalid_instruction;
+    }
+
     if (instr_is_comptime(ptr)) {
         bool dest_allows_addr_zero = ptr_allows_addr_zero(dest_type);
         UndefAllowed is_undef_allowed = dest_allows_addr_zero ? UndefOk : UndefBad;
@@ -26649,23 +26666,6 @@ static IrInstruction *ir_analyze_ptr_cast(IrAnalyze *ira, IrInstruction *source_
 
     IrInstruction *casted_ptr = ir_build_ptr_cast_gen(ira, source_instr, dest_type, ptr, safety_check_on);
 
-    if ((err = type_resolve(ira->codegen, dest_type, ResolveStatusZeroBitsKnown)))
-        return ira->codegen->invalid_instruction;
-
-    if ((err = type_resolve(ira->codegen, src_type, ResolveStatusZeroBitsKnown)))
-        return ira->codegen->invalid_instruction;
-
-    if (type_has_bits(dest_type) && !type_has_bits(src_type)) {
-        ErrorMsg *msg = ir_add_error(ira, source_instr,
-            buf_sprintf("'%s' and '%s' do not have the same in-memory representation",
-                buf_ptr(&src_type->name), buf_ptr(&dest_type->name)));
-        add_error_note(ira->codegen, msg, ptr->source_node,
-                buf_sprintf("'%s' has no in-memory bits", buf_ptr(&src_type->name)));
-        add_error_note(ira->codegen, msg, dest_type_src->source_node,
-                buf_sprintf("'%s' has in-memory bits", buf_ptr(&dest_type->name)));
-        return ira->codegen->invalid_instruction;
-    }
-
     // Keep the bigger alignment, it can only help-
     // unless the target is zero bits.
     IrInstruction *result;
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 450f91b9be..a653e1662e 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -2,6 +2,16 @@ const tests = @import("tests.zig");
 const builtin = @import("builtin");
 
 pub fn addCases(cases: *tests.CompileErrorContext) void {
+    cases.add("comptime ptrcast of zero-sized type",
+        \\fn foo() void {
+        \\    const node: struct {} = undefined;
+        \\    const vla_ptr = @ptrCast([*]const u8, &node);
+        \\}
+        \\comptime { foo(); }
+    , &[_][]const u8{
+        "tmp.zig:3:21: error: '*const struct:2:17' and '[*]const u8' do not have the same in-memory representation",
+    });
+
     cases.add("slice sentinel mismatch",
         \\fn foo() [:0]u8 {
         \\    var x: []u8 = undefined;