C pointers: errors for nested pointer casting regarding null

See #1059

1 files changed, 33 insertions, 12 deletions

diff --git a/src/analyze.cpp b/src/analyze.cpp
index ab2afba561..900def52d4 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -433,6 +433,9 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
         bool is_volatile, PtrLen ptr_len, uint32_t byte_alignment,
         uint32_t bit_offset_in_host, uint32_t host_int_bytes)
 {
+    // TODO when implementing https://github.com/ziglang/zig/issues/1953
+    // move this to a parameter
+    bool allow_zero = (ptr_len == PtrLenC);
     assert(!type_is_invalid(child_type));
     assert(ptr_len != PtrLenUnknown || child_type->id != ZigTypeIdOpaque);
 
@@ -452,7 +455,7 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
 
     TypeId type_id = {};
     ZigType **parent_pointer = nullptr;
-    if (host_int_bytes != 0 || is_volatile || byte_alignment != 0 || ptr_len != PtrLenSingle) {
+    if (host_int_bytes != 0 || is_volatile || byte_alignment != 0 || ptr_len != PtrLenSingle || allow_zero) {
         type_id.id = ZigTypeIdPointer;
         type_id.data.pointer.child_type = child_type;
         type_id.data.pointer.is_const = is_const;
@@ -461,6 +464,7 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
         type_id.data.pointer.bit_offset_in_host = bit_offset_in_host;
         type_id.data.pointer.host_int_bytes = host_int_bytes;
         type_id.data.pointer.ptr_len = ptr_len;
+        type_id.data.pointer.allow_zero = allow_zero;
 
         auto existing_entry = g->type_table.maybe_get(type_id);
         if (existing_entry)
@@ -481,18 +485,28 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
     const char *star_str = ptr_len_to_star_str(ptr_len);
     const char *const_str = is_const ? "const " : "";
     const char *volatile_str = is_volatile ? "volatile " : "";
+    const char *allow_zero_str;
+    if (ptr_len == PtrLenC) {
+        assert(allow_zero);
+        allow_zero_str = "";
+    } else {
+        allow_zero_str = allow_zero ? "allowzero " : "";
+    }
     buf_resize(&entry->name, 0);
     if (host_int_bytes == 0 && byte_alignment == 0) {
-        buf_appendf(&entry->name, "%s%s%s%s", star_str, const_str, volatile_str, buf_ptr(&child_type->name));
+        buf_appendf(&entry->name, "%s%s%s%s%s",
+                star_str, const_str, volatile_str, allow_zero_str, buf_ptr(&child_type->name));
     } else if (host_int_bytes == 0) {
-        buf_appendf(&entry->name, "%salign(%" PRIu32 ") %s%s%s", star_str, byte_alignment,
-                const_str, volatile_str, buf_ptr(&child_type->name));
+        buf_appendf(&entry->name, "%salign(%" PRIu32 ") %s%s%s%s", star_str, byte_alignment,
+                const_str, volatile_str, allow_zero_str, buf_ptr(&child_type->name));
     } else if (byte_alignment == 0) {
-        buf_appendf(&entry->name, "%salign(:%" PRIu32 ":%" PRIu32 ") %s%s%s", star_str,
-                bit_offset_in_host, host_int_bytes, const_str, volatile_str, buf_ptr(&child_type->name));
+        buf_appendf(&entry->name, "%salign(:%" PRIu32 ":%" PRIu32 ") %s%s%s%s", star_str,
+                bit_offset_in_host, host_int_bytes, const_str, volatile_str, allow_zero_str,
+                buf_ptr(&child_type->name));
     } else {
-        buf_appendf(&entry->name, "%salign(%" PRIu32 ":%" PRIu32 ":%" PRIu32 ") %s%s%s", star_str, byte_alignment,
-                bit_offset_in_host, host_int_bytes, const_str, volatile_str, buf_ptr(&child_type->name));
+        buf_appendf(&entry->name, "%salign(%" PRIu32 ":%" PRIu32 ":%" PRIu32 ") %s%s%s%s", star_str, byte_alignment,
+                bit_offset_in_host, host_int_bytes, const_str, volatile_str, allow_zero_str,
+                buf_ptr(&child_type->name));
     }
 
     assert(child_type->id != ZigTypeIdInvalid);
@@ -500,7 +514,9 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
     entry->zero_bits = !type_has_bits(child_type);
 
     if (!entry->zero_bits) {
-        if (is_const || is_volatile || byte_alignment != 0 || ptr_len != PtrLenSingle || bit_offset_in_host != 0) {
+        if (is_const || is_volatile || byte_alignment != 0 || ptr_len != PtrLenSingle ||
+            bit_offset_in_host != 0 || allow_zero)
+        {
             ZigType *peer_type = get_pointer_to_type_extra(g, child_type, false, false,
                     PtrLenSingle, 0, 0, host_int_bytes);
             entry->type_ref = peer_type->type_ref;
@@ -534,6 +550,7 @@ ZigType *get_pointer_to_type_extra(CodeGen *g, ZigType *child_type, bool is_cons
     entry->data.pointer.explicit_alignment = byte_alignment;
     entry->data.pointer.bit_offset_in_host = bit_offset_in_host;
     entry->data.pointer.host_int_bytes = host_int_bytes;
+    entry->data.pointer.allow_zero = allow_zero;
 
     if (parent_pointer) {
         *parent_pointer = entry;
@@ -850,7 +867,7 @@ ZigType *get_slice_type(CodeGen *g, ZigType *ptr_type) {
 
     ZigType *child_type = ptr_type->data.pointer.child_type;
     if (ptr_type->data.pointer.is_const || ptr_type->data.pointer.is_volatile ||
-        ptr_type->data.pointer.explicit_alignment != 0)
+        ptr_type->data.pointer.explicit_alignment != 0 || ptr_type->data.pointer.allow_zero)
     {
         ZigType *peer_ptr_type = get_pointer_to_type_extra(g, child_type, false, false,
                 PtrLenUnknown, 0, 0, 0);
@@ -873,7 +890,7 @@ ZigType *get_slice_type(CodeGen *g, ZigType *ptr_type) {
         ZigType *child_ptr_type = child_type->data.structure.fields[slice_ptr_index].type_entry;
         assert(child_ptr_type->id == ZigTypeIdPointer);
         if (child_ptr_type->data.pointer.is_const || child_ptr_type->data.pointer.is_volatile ||
-            child_ptr_type->data.pointer.explicit_alignment != 0)
+            child_ptr_type->data.pointer.explicit_alignment != 0 || child_ptr_type->data.pointer.allow_zero)
         {
             ZigType *grand_child_type = child_ptr_type->data.pointer.child_type;
             ZigType *bland_child_ptr_type = get_pointer_to_type_extra(g, grand_child_type, false, false,
@@ -4053,7 +4070,9 @@ ZigType *get_src_ptr_type(ZigType *type) {
     if (type->id == ZigTypeIdFn) return type;
     if (type->id == ZigTypeIdPromise) return type;
     if (type->id == ZigTypeIdOptional) {
-        if (type->data.maybe.child_type->id == ZigTypeIdPointer) return type->data.maybe.child_type;
+        if (type->data.maybe.child_type->id == ZigTypeIdPointer) {
+            return type->data.maybe.child_type->data.pointer.allow_zero ? nullptr : type->data.maybe.child_type;
+        }
         if (type->data.maybe.child_type->id == ZigTypeIdFn) return type->data.maybe.child_type;
         if (type->data.maybe.child_type->id == ZigTypeIdPromise) return type->data.maybe.child_type;
     }
@@ -6289,6 +6308,7 @@ uint32_t type_id_hash(TypeId x) {
                 ((x.data.pointer.ptr_len == PtrLenSingle) ? (uint32_t)1120226602 : (uint32_t)3200913342) +
                 (x.data.pointer.is_const ? (uint32_t)2749109194 : (uint32_t)4047371087) +
                 (x.data.pointer.is_volatile ? (uint32_t)536730450 : (uint32_t)1685612214) +
+                (x.data.pointer.allow_zero ? (uint32_t)3324284834 : (uint32_t)3584904923) +
                 (((uint32_t)x.data.pointer.alignment) ^ (uint32_t)0x777fbe0e) +
                 (((uint32_t)x.data.pointer.bit_offset_in_host) ^ (uint32_t)2639019452) +
                 (((uint32_t)x.data.pointer.host_int_bytes) ^ (uint32_t)529908881);
@@ -6339,6 +6359,7 @@ bool type_id_eql(TypeId a, TypeId b) {
                 a.data.pointer.ptr_len == b.data.pointer.ptr_len &&
                 a.data.pointer.is_const == b.data.pointer.is_const &&
                 a.data.pointer.is_volatile == b.data.pointer.is_volatile &&
+                a.data.pointer.allow_zero == b.data.pointer.allow_zero &&
                 a.data.pointer.alignment == b.data.pointer.alignment &&
                 a.data.pointer.bit_offset_in_host == b.data.pointer.bit_offset_in_host &&
                 a.data.pointer.host_int_bytes == b.data.pointer.host_int_bytes;