checker: check filter, map and sort left type (#6952)

vlib/builtin/string.v

@@ -1490,34 +1490,6 @@ pub fn (s string) fields() []string {
 	return s.replace('\t', ' ').split(' ')
 }
 
-pub fn (s string) map(func fn(byte) byte) string {
-	unsafe {
-		mut res := malloc(s.len + 1)
-		for i in 0..s.len {
-			res[i] = func(s[i])
-		}
-		return tos(res, s.len)
-	}
-}
-
-pub fn (s string) filter(func fn(b byte) bool) string {
-	mut new_len := 0
-	mut buf := malloc(s.len + 1)
-	for i in 0 .. s.len {
-		mut b := s[i]
-		if func(b) {
-			unsafe {
-				buf[new_len] = b
-			}
-			new_len++
-		}
-	}
-	unsafe {
-		buf[new_len] = 0
-		return buf.vstring_with_len(new_len)
-	}
-}
-
 // Allows multi-line strings to be formatted in a way that removes white-space
 // before a delimeter. by default `|` is used.
 // Note: the delimiter has to be a byte at this time. That means surrounding

vlib/builtin/string_test.v

@@ -816,41 +816,10 @@ fn test_double_quote_inter() {
 	assert '${a} ${b}' == "1 2"
 }
 
-fn test_string_map() {
-	$if windows {
-		// TODO
-		return
-	}
-	original := 'Hello'
-	println('original.len = $original.len')
-	a := original.map(fn (b byte) byte {
-		return b + 1
-	})
-	expected := 'Ifmmp'
-	println('a[0] = ' + a[0].str())
-	println('a[1] = ' + a[1].str())
-	println('a[2] = ' + a[2].str())
-	println('a[3] = ' + a[3].str())
-	println('a[4] = ' + a[4].str())
-	println('a.len = $a.len')
-	assert a.len == expected.len
-	assert a == expected
-
-	assert 'foo'.map(foo) == r'\ee'
-}
-
 fn foo(b byte) byte {
 	return b - 10
 }
 
-fn test_string_filter() {
-	foo := 'V is awesome!!!!'.filter(fn (b byte) bool {
-		return b != `!`
-	})
-	assert foo == 'V is awesome'
-	assert 'Alexander'.filter(filter) == 'Alexnder'
-}
-
 fn filter(b byte) bool {
 	return b != `a`
 }