checker: warn when casting between reference types outside of `unsafe` (#7892)

vlib/live/common.v

@@ -60,7 +60,9 @@ pub fn info() &LiveReloadInfo {
 	// started, and the structure LiveReloadInfo will not get updated.
 	// All its fields will be 0, but still safe to access.
 	mut x := &LiveReloadInfo{}
-	mut p := &u64(&C.g_live_info)
-	unsafe { *p = &u64(x) }        
+	unsafe { 
+		mut p := &u64(&C.g_live_info)
+		*p = &u64(x) 
+	}        
 	return x
 }

vlib/math/unsafe.v

@@ -6,7 +6,7 @@ module math
 // with the sign bit of f and the result in the same bit position.
 // f32_bits(f32_from_bits(x)) == x.
 pub fn f32_bits(f f32) u32 {
-	p := *(&u32(&f))
+	p := *unsafe {&u32(&f)}
 	return p
 }
 
@@ -15,7 +15,7 @@ pub fn f32_bits(f f32) u32 {
 // and the result in the same bit position.
 // f32_from_bits(f32_bits(x)) == x.
 pub fn f32_from_bits(b u32) f32 {
-	p := *(&f32(&b))
+	p := *unsafe {&f32(&b)}
 	return p
 }
 
@@ -23,7 +23,7 @@ pub fn f32_from_bits(b u32) f32 {
 // with the sign bit of f and the result in the same bit position,
 // and f64_bits(f64_from_bits(x)) == x.
 pub fn f64_bits(f f64) u64 {
-	p := *(&u64(&f))
+	p := *unsafe {&u64(&f)}
 	return p
 }
 
@@ -32,7 +32,7 @@ pub fn f64_bits(f f64) u64 {
 // and the result in the same bit position.
 // f64_from_bits(f64_bits(x)) == x.
 pub fn f64_from_bits(b u64) f64 {
-	p := *(&f64(&b))
+	p := *unsafe {&f64(&b)}
 	return p
 }
 

vlib/net/address.v

@@ -40,7 +40,7 @@ fn new_addr(addr C.sockaddr) ?Addr {
 	}
 	mut saddr := buf.bytestr()
 
-	hport := (&C.sockaddr_in(&addr)).sin_port
+	hport := unsafe {&C.sockaddr_in(&addr)}.sin_port
 	port := C.ntohs(hport)
 
 	$if windows {

vlib/net/tcp.v

@@ -160,7 +160,7 @@ pub fn (c TcpConn) peer_ip() ?string {
 	buf := [44]byte{}
 	peeraddr := C.sockaddr_in{}
 	speeraddr := sizeof(peeraddr)
-	socket_error(C.getpeername(c.sock.handle, &C.sockaddr(&peeraddr), &speeraddr)) ?
+	socket_error(C.getpeername(c.sock.handle, unsafe {&C.sockaddr(&peeraddr)}, &speeraddr)) ?
 	cstr := C.inet_ntop(C.AF_INET, &peeraddr.sin_addr, buf, sizeof(buf))
 	if cstr == 0 {
 		return error('net.peer_ip: inet_ntop failed')
@@ -190,7 +190,7 @@ pub fn listen_tcp(port int) ?TcpListener {
 	addr.sin_addr.s_addr = C.htonl(C.INADDR_ANY)
 	size := sizeof(C.sockaddr_in)
 	// cast to the correct type
-	sockaddr := &C.sockaddr(&addr)
+	sockaddr := unsafe {&C.sockaddr(&addr)}
 	socket_error(C.bind(s.handle, sockaddr, size)) ?
 	socket_error(C.listen(s.handle, 128)) ?
 	return TcpListener{
@@ -205,7 +205,7 @@ pub fn (l TcpListener) accept() ?TcpConn {
 	unsafe { C.memset(&addr, 0, sizeof(C.sockaddr_storage)) }
 	size := sizeof(C.sockaddr_storage)
 	// cast to correct type
-	sock_addr := &C.sockaddr(&addr)
+	sock_addr := unsafe {&C.sockaddr(&addr)}
 	mut new_handle := C.accept(l.sock.handle, sock_addr, &size)
 	if new_handle <= 0 {
 		l.wait_for_accept() ?
@@ -344,7 +344,7 @@ pub fn (s TcpSocket) address() ?Addr {
 	mut addr := C.sockaddr_in{}
 	size := sizeof(C.sockaddr_in)
 	// cast to the correct type
-	sockaddr := &C.sockaddr(&addr)
+	sockaddr := unsafe {&C.sockaddr(&addr)}
 	C.getsockname(s.handle, sockaddr, &size)
 	return new_addr(sockaddr)
 }

vlib/net/udp.v

@@ -218,7 +218,7 @@ fn new_udp_socket(local_port int) ?UdpSocket {
 	size := sizeof(C.sockaddr_in)
 
 	// cast to the correct type
-	sockaddr := &C.sockaddr(&addr)
+	sockaddr := unsafe {&C.sockaddr(&addr)}
 
 	socket_error(C.bind(s.handle, sockaddr, size))?
 

vlib/regex/regex.v

@@ -474,7 +474,7 @@ enum CharClass_parse_state {
 
 fn (re RE) get_char_class(pc int) string {
 	buf := []byte{len:(re.cc.len)}
-	mut buf_ptr := &byte(&buf)
+	mut buf_ptr := unsafe {&byte(&buf)}
 
 	mut cc_i := re.prog[pc].cc_index
 	mut i := 0

vlib/strconv/atof_test.v

@@ -62,8 +62,8 @@ fn test_atof() {
 
 	// special cases
 	mut f1 := f64(0.0)
-	mut ptr := &u64(&f1)
-	ptr = &u64(&f1)
+	mut ptr := unsafe {&u64(&f1)}
+	ptr = unsafe {&u64(&f1)}
 
 	// double_plus_zero
 	f1=0.0

vlib/v/ast/ast.v

@@ -948,7 +948,7 @@ pub:
 	typ       table.Type // `string` TODO rename to `type_to_cast_to`
 	pos       token.Position
 pub mut:
-	typname   string
+	typname   string     // TypeSymbol.name
 	expr_type table.Type // `byteptr`
 	has_arg   bool
 	in_prexpr bool // is the parent node an ast.PrefixExpr

vlib/v/checker/checker.v

@@ -3421,6 +3421,10 @@ pub fn (mut c Checker) cast_expr(mut node ast.CastExpr) table.Type {
 		// variadic case can happen when arrays are converted into variadic
 		msg := if node.expr_type.has_flag(.optional) { 'an optional' } else { 'a variadic' }
 		c.error('cannot type cast $msg', node.pos)
+	} else if !c.inside_unsafe && node.typ.is_ptr() && node.expr_type.is_ptr() {
+		ft := c.table.type_to_str(node.expr_type)
+		tt := c.table.type_to_str(node.typ)
+		c.warn('casting `$ft` to `$tt` is only allowed in `unsafe` code', node.pos)
 	}
 	if node.has_arg {
 		c.expr(node.arg)