checker: warn if unsafe method called outside unsafe block (#5863)

vlib/builtin/array.v

@@ -331,12 +331,18 @@ pub fn (a &array) clone() array {
 	if a.element_size == sizeof(array) {
 		for i in 0..a.len {
 			ar := array{}
-			C.memcpy(&ar, a.get_unsafe(i), sizeof(array))
+			unsafe {
+				C.memcpy(&ar, a.get_unsafe(i), sizeof(array))
+			}
 			ar_clone := ar.clone()
-			arr.set_unsafe(i, &ar_clone)
+			unsafe {
+				arr.set_unsafe(i, &ar_clone)
+			}
 		}
 	} else {
-		C.memcpy(byteptr(arr.data), a.data, a.cap * a.element_size)
+		unsafe {
+			C.memcpy(byteptr(arr.data), a.data, a.cap * a.element_size)
+		}
 	}
 	return arr
 }
@@ -681,7 +687,9 @@ pub fn compare_f32(a, b &f32) int {
 pub fn (a array) pointers() []voidptr {
 	mut res := []voidptr{}
 	for i in 0..a.len {
-		res << a.get_unsafe(i)
+		unsafe {
+			res << a.get_unsafe(i)
+		}
 	}
 	return res
 }

vlib/builtin/map.v

@@ -517,7 +517,7 @@ pub fn (m map) clone() map {
 		cap:             m.cap
 		cached_hashbits: m.cached_hashbits
 		shift:           m.shift
-		key_values:      m.key_values.clone()
+		key_values:      unsafe {m.key_values.clone()}
 		metas:           &u32(malloc(int(metas_size)))
 		extra_metas:     m.extra_metas
 		len:            m.len

vlib/builtin/string.v

@@ -1201,11 +1201,14 @@ pub fn (u ustring) at(idx int) string {
 	return u.substr(idx, idx + 1)
 }
 
+[unsafe_fn]
 fn (u &ustring) free() {
 	$if prealloc {
 		return
 	}
-	u.runes.free()
+	unsafe {
+		u.runes.free()
+	}
 }
 
 pub fn (c byte) is_digit() bool {

vlib/v/builder/compile.v

@@ -42,17 +42,22 @@ pub fn compile(command string, pref &pref.Preferences) {
 		println('compilation took: $sw.elapsed().milliseconds() ms')
 	}
 	// running does not require the parsers anymore
-	b.myfree()
+	unsafe {
+		b.myfree()
+	}
 	if pref.is_test || pref.is_run {
 		b.run_compiled_executable_and_exit()
 	}
 }
 
 // Temporary, will be done by -autofree
+[unsafe_fn]
 fn (mut b Builder) myfree() {
 	// for file in b.parsed_files {
 	// }
-	b.parsed_files.free()
+	unsafe {
+		b.parsed_files.free()
+	}
 }
 
 fn (mut b Builder) run_compiled_executable_and_exit() {

vlib/v/checker/checker.v

@@ -954,6 +954,10 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 				}
 			}
 		}
+		if method.is_unsafe && !c.inside_unsafe {
+			c.warn('method `${left_type_sym.name}.$method_name` must be called from an `unsafe` block',
+				call_expr.pos)
+		}
 		// TODO: typ optimize.. this node can get processed more than once
 		if call_expr.expected_arg_types.len == 0 {
 			for i in 1 .. method.args.len {

vlib/v/parser/fn.v

@@ -123,6 +123,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 	p.top_level_statement_start()
 	start_pos := p.tok.position()
 	is_deprecated := 'deprecated' in p.attrs
+	is_unsafe := 'unsafe_fn' in p.attrs
 	is_pub := p.tok.kind == .key_pub
 	if is_pub {
 		p.next()
@@ -250,6 +251,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			is_generic: is_generic
 			is_pub: is_pub
 			is_deprecated: is_deprecated
+			is_unsafe: is_unsafe
 			ctdefine: ctdefine
 			mod: p.mod
 			attrs: p.attrs
@@ -271,12 +273,13 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			args: args
 			return_type: return_type
 			is_variadic: is_variadic
-			language: language
 			is_generic: is_generic
 			is_pub: is_pub
 			is_deprecated: is_deprecated
+			is_unsafe: is_unsafe
 			ctdefine: ctdefine
 			mod: p.mod
+			language: language
 		})
 	}
 	// Body

vlib/v/table/table.v

@@ -29,6 +29,7 @@ pub:
 	is_generic    bool
 	is_pub        bool
 	is_deprecated bool
+	is_unsafe     bool
 	mod           string
 	ctdefine      string // compile time define. myflag, when [if myflag] tag
 	attrs []string

vlib/v/tests/unsafe.out

@@ -0,0 +1,34 @@
+unsafe.v:4:6: warning: pointer arithmetic is only allowed in `unsafe` blocks
+    2 |     v := 5
+    3 |     mut p := &v
+    4 |     p++
+      |      ~~
+    5 |     p += 2
+    6 |     _ := v
+unsafe.v:5:7: warning: pointer arithmetic is only allowed in `unsafe` blocks
+    3 |     mut p := &v
+    4 |     p++
+    5 |     p += 2
+      |       ~~
+    6 |     _ := v
+    7 | }
+unsafe.v:11:14: warning: pointer arithmetic is only allowed in `unsafe` blocks
+    9 | fn test_ptr_infix() {
+   10 |     v := 4
+   11 |     mut q := &v - 1
+      |              ^
+   12 |     q = q + 3
+   13 |     _ := q
+unsafe.v:12:9: warning: pointer arithmetic is only allowed in `unsafe` blocks
+   10 |     v := 4
+   11 |     mut q := &v - 1
+   12 |     q = q + 3
+      |         ^
+   13 |     _ := q
+   14 |     _ := v
+unsafe.v:24:7: warning: method `S1.f` must be called from an `unsafe` block
+   22 | fn test_funcs() {
+   23 |     s := S1{}
+   24 |     s.f()
+      |       ~~~
+   25 | }

vlib/v/tests/unsafe.v

@@ -0,0 +1,25 @@
+fn test_ptr_assign() {
+    v := 5
+    mut p := &v
+    p++
+    p += 2
+    _ := v
+}
+
+fn test_ptr_infix() {
+    v := 4
+    mut q := &v - 1
+    q = q + 3
+    _ := q
+    _ := v
+}
+
+struct S1 {}
+
+[unsafe_fn]
+fn (s S1) f(){}
+
+fn test_funcs() {
+    s := S1{}
+    s.f()
+}