ir: Various fixes for comptime ptr handling

* Correctly fold ptrToInt on optional types
* Generate null as ConstPtrSpecialNull in intToPtr
* Correctly stop ptrToInt on ?*T where T is zero-sized

Closes #4535

1 files changed, 21 insertions, 7 deletions

diff --git a/src/ir.cpp b/src/ir.cpp
index b0fc8dccd7..77c7c74197 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -27851,9 +27851,15 @@ static IrInstGen *ir_analyze_int_to_ptr(IrAnalyze *ira, IrInst* source_instr, Ir
         }
 
         IrInstGen *result = ir_const(ira, source_instr, ptr_type);
-        result->value->data.x_ptr.special = ConstPtrSpecialHardCodedAddr;
-        result->value->data.x_ptr.mut = ConstPtrMutRuntimeVar;
-        result->value->data.x_ptr.data.hard_coded_addr.addr = addr;
+        if (ptr_type->id == ZigTypeIdOptional && addr == 0) {
+            result->value->data.x_ptr.special = ConstPtrSpecialNull;
+            result->value->data.x_ptr.mut = ConstPtrMutComptimeConst;
+        } else {
+            result->value->data.x_ptr.special = ConstPtrSpecialHardCodedAddr;
+            result->value->data.x_ptr.mut = ConstPtrMutRuntimeVar;
+            result->value->data.x_ptr.data.hard_coded_addr.addr = addr;
+        }
+
         return result;
     }
 
@@ -27911,15 +27917,15 @@ static IrInstGen *ir_analyze_instruction_ptr_to_int(IrAnalyze *ira, IrInstSrcPtr
 
     ZigType *usize = ira->codegen->builtin_types.entry_usize;
 
-    // We check size explicitly so we can use get_src_ptr_type here.
-    if (get_src_ptr_type(target->value->type) == nullptr) {
+    ZigType *src_ptr_type = get_src_ptr_type(target->value->type);
+    if (src_ptr_type == nullptr) {
         ir_add_error(ira, &target->base,
                 buf_sprintf("expected pointer, found '%s'", buf_ptr(&target->value->type->name)));
         return ira->codegen->invalid_inst_gen;
     }
 
     bool has_bits;
-    if ((err = type_has_bits2(ira->codegen, target->value->type, &has_bits)))
+    if ((err = type_has_bits2(ira->codegen, src_ptr_type, &has_bits)))
         return ira->codegen->invalid_inst_gen;
 
     if (!has_bits) {
@@ -27932,11 +27938,19 @@ static IrInstGen *ir_analyze_instruction_ptr_to_int(IrAnalyze *ira, IrInstSrcPtr
         ZigValue *val = ir_resolve_const(ira, target, UndefBad);
         if (!val)
             return ira->codegen->invalid_inst_gen;
-        if (val->type->id == ZigTypeIdPointer && val->data.x_ptr.special == ConstPtrSpecialHardCodedAddr) {
+
+        // Since we've already run this type trough get_codegen_ptr_type it is
+        // safe to access the x_ptr fields
+        if (val->data.x_ptr.special == ConstPtrSpecialHardCodedAddr) {
             IrInstGen *result = ir_const(ira, &instruction->base.base, usize);
             bigint_init_unsigned(&result->value->data.x_bigint, val->data.x_ptr.data.hard_coded_addr.addr);
             result->value->type = usize;
             return result;
+        } else if (val->data.x_ptr.special == ConstPtrSpecialNull) {
+            IrInstGen *result = ir_const(ira, &instruction->base.base, usize);
+            bigint_init_unsigned(&result->value->data.x_bigint, 0);
+            result->value->type = usize;
+            return result;
         }
     }