checker: warn when casting number or a voidptr to reference type outside unsafe (#7900)

vlib/builtin/map.v

@@ -230,44 +230,44 @@ pub mut:
 }
 
 fn map_hash_string(pkey voidptr) u64 {
-	key := *&string(pkey)
+	key := *unsafe { &string(pkey) }
 	return hash.wyhash_c(key.str, u64(key.len), 0)
 }
 
 fn map_hash_int_1(pkey voidptr) u64 {
-	return hash.wyhash64_c(*&byte(pkey), 0)
+	return hash.wyhash64_c(*unsafe { &byte(pkey) }, 0)
 }
 
 fn map_hash_int_2(pkey voidptr) u64 {
-	return hash.wyhash64_c(*&u16(pkey), 0)
+	return hash.wyhash64_c(*unsafe { &u16(pkey) }, 0)
 }
 
 fn map_hash_int_4(pkey voidptr) u64 {
-	return hash.wyhash64_c(*&u32(pkey), 0)
+	return hash.wyhash64_c(*unsafe { &u32(pkey) }, 0)
 }
 
 fn map_hash_int_8(pkey voidptr) u64 {
-	return hash.wyhash64_c(*&u64(pkey), 0)
+	return hash.wyhash64_c(*unsafe { &u64(pkey) }, 0)
 }
 
 fn map_eq_string(a voidptr, b voidptr) bool {
-	return fast_string_eq(*&string(a), *&string(b))
+	return fast_string_eq(*unsafe { &string(a) }, *unsafe { &string(b) })
 }
 
 fn map_eq_int_1(a voidptr, b voidptr) bool {
-	return *&byte(a) == *&byte(b)
+	return unsafe { *&byte(a) == *&byte(b) }
 }
 
 fn map_eq_int_2(a voidptr, b voidptr) bool {
-	return *&u16(a) == *&u16(b)
+	return unsafe { *&u16(a) == *&u16(b) }
 }
 
 fn map_eq_int_4(a voidptr, b voidptr) bool {
-	return *&u32(a) == *&u32(b)
+	return unsafe { *&u32(a) == *&u32(b) }
 }
 
 fn map_eq_int_8(a voidptr, b voidptr) bool {
-	return *&u64(a) == *&u64(b)
+	return unsafe { *&u64(a) == *&u64(b) }
 }
 
 fn map_clone_string(dest voidptr, pkey voidptr) {
@@ -302,7 +302,7 @@ fn map_clone_int_8(dest voidptr, pkey voidptr) {
 }
 
 fn map_free_string(pkey voidptr) {
-	(*&string(pkey)).free()
+	(*unsafe { &string(pkey) }).free()
 }
 
 fn map_free_nop(_ voidptr) {

vlib/gg/gg.v

@@ -91,7 +91,7 @@ pub:
 }
 
 fn gg_init_sokol_window(user_data voidptr) {
-	mut g := &Context(user_data)
+	mut g := unsafe { &Context(user_data) }
 	desc := sapp.create_desc()
 	/*
 	desc := C.sg_desc{
@@ -159,7 +159,7 @@ fn gg_init_sokol_window(user_data voidptr) {
 }
 
 fn gg_frame_fn(user_data voidptr) {
-	mut ctx := &Context(user_data)
+	mut ctx := unsafe { &Context(user_data) }
 	if ctx.config.frame_fn == voidptr(0) {
 		return
 	}
@@ -180,8 +180,8 @@ pub fn (mut ctx Context) refresh_ui() {
 }
 
 fn gg_event_fn(ce &C.sapp_event, user_data voidptr) {
-	e := &sapp.Event(ce)
-	mut g := &Context(user_data)
+	e := unsafe { &sapp.Event(ce) }
+	mut g := unsafe { &Context(user_data) }
 	if g.config.event_fn != voidptr(0) {
 		g.config.event_fn(e, g.config.user_data)
 	}
@@ -215,14 +215,14 @@ fn gg_event_fn(ce &C.sapp_event, user_data voidptr) {
 }
 
 fn gg_cleanup_fn(user_data voidptr) {
-	mut g := &Context(user_data)
+	mut g := unsafe { &Context(user_data) }
 	if g.config.cleanup_fn != voidptr(0) {
 		g.config.cleanup_fn(g.config.user_data)
 	}
 }
 
 fn gg_fail_fn(msg charptr, user_data voidptr) {
-	mut g := &Context(user_data)
+	mut g := unsafe { &Context(user_data) }
 	vmsg := tos3(msg)
 	if g.config.fail_fn != voidptr(0) {
 		g.config.fail_fn(vmsg, g.config.user_data)

vlib/live/common.v

@@ -52,7 +52,7 @@ pub mut:
 // so that the user can set callbacks, read meta information, etc.
 pub fn info() &LiveReloadInfo {
 	if C.g_live_info != 0 {
-		return &LiveReloadInfo(C.g_live_info)
+		return unsafe {&LiveReloadInfo(C.g_live_info)}
 	}
 	// When the current program is not compiled with -live, simply
 	// return a new empty struct LiveReloadInfo in order to prevent

vlib/os/environment.c.v

@@ -81,7 +81,7 @@ pub fn environ() map[string]string {
 		}
 		C.FreeEnvironmentStringsW(estrings)
 	} $else {
-		e := &charptr(C.environ)
+		e := unsafe { &charptr(C.environ) }
 		for i := 0; !isnil(unsafe { e[i] }); i++ {
 			eline := unsafe { cstring_to_vstring(byteptr(e[i])) }
 			eq_index := eline.index_byte(`=`)

vlib/picoev/picoev.v

@@ -143,7 +143,7 @@ fn mysubstr(s byteptr, from int, len int) string {
 }
 
 fn rw_callback(loop &C.picoev_loop, fd int, events int, cb_arg voidptr) {
-	mut p := &Picoev(cb_arg)
+	mut p := unsafe {&Picoev(cb_arg)}
 	if (events & C.PICOEV_TIMEOUT) != 0 {
 		close_conn(loop, fd)
 		p.idx[fd] = 0

vlib/sync/pool.v

@@ -164,7 +164,7 @@ fn process_in_thread(mut pool PoolProcessor, task_id int) {
 pub fn (pool &PoolProcessor) get_string_item(idx int) string {
    // return *(&string(pool.items[idx]))
    // TODO: the below is a hack, remove it when v2 casting works again
-   return *(&string( pool.items[idx] ))
+   return *unsafe {&string( pool.items[idx] )}
 }
 
 // get_int_item - called by the worker callback.
@@ -172,7 +172,7 @@ pub fn (pool &PoolProcessor) get_string_item(idx int) string {
 // TODO: remove the need for this when vfmt becomes smarter.
 pub fn (pool &PoolProcessor) get_int_item(idx int) int {
 	item := pool.items[idx]
-	return *(&int(item))
+	return *unsafe {&int(item)}
 }
 
 // TODO: uncomment, when generics work again
@@ -241,14 +241,14 @@ pub fn (mut pool PoolProcessor) work_on_items_i(items []int) {
 pub fn (pool &PoolProcessor) get_results_s() []SResult {
 	mut res := []SResult{}
 	for i in 0 .. pool.results.len {
-		res << *(&SResult(pool.results[i]))
+		res << *unsafe {&SResult(pool.results[i])}
 	}
 	return res
 }
 pub fn (pool &PoolProcessor) get_results_i() []IResult {
 	mut res := []IResult{}
 	for i in 0 .. pool.results.len {
-		res << *(&IResult(pool.results[i]))
+		res << *unsafe {&IResult(pool.results[i])}
 	}
 	return res
 }

vlib/v/checker/checker.v

@@ -3426,10 +3426,13 @@ 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 $msg', node.pos)
-	} else if !c.inside_unsafe && node.typ.is_ptr() && node.expr_type.is_ptr() {
+	} else if !c.inside_unsafe && node.typ.is_ptr() &&
+		(node.expr_type.is_ptr() || node.expr_type == table.voidptr_type ||
+		(node.expr_type.is_number() && node.expr !is ast.IntegerLiteral)) {
+		// ignore &Type(0) for now
 		ft := c.table.type_to_str(node.expr_type)
 		tt := c.table.type_to_str(node.typ)
-		c.warn('casting `$ft` to `$tt` is only allowed in `unsafe` code', node.pos)
+		c.warn('casting a `$ft` to `$tt` is only allowed in `unsafe` code', node.pos)
 	}
 	if node.has_arg {
 		c.expr(node.arg)
@@ -5183,7 +5186,7 @@ fn (mut c Checker) verify_all_vweb_routes() {
 			if m.return_type == typ_vweb_result {
 				is_ok, nroute_attributes, nargs := c.verify_vweb_params_for_method(m)
 				if !is_ok {
-					f := &ast.FnDecl(m.source_fn)
+					f := unsafe { &ast.FnDecl(m.source_fn) }
 					if isnil(f) {
 						continue
 					}