Revert "Revert "builder: create the binary in the current directory if -o is not provided""

This reverts commit f2b73fe3ca.

vlib/v/checker/tests/in_mismatch_type.out

@@ -12,14 +12,14 @@ vlib/v/checker/tests/in_mismatch_type.vv:13:5: error: left operand to `in` does
       |        ~~~~~~
    14 |         println('yeah')
    15 |     }
-vlib/v/checker/tests/in_mismatch_type.vv:16:5: error: left operand to `in` does not match: expected `string`, not `int literal`
+vlib/v/checker/tests/in_mismatch_type.vv:16:5: error: use `str.contains(substr)` instead of `substr in str`
    14 |         println('yeah')
    15 |     }
    16 |     if 3 in s {
       |        ~~~~~~
    17 |         println('dope')
    18 |     }
-vlib/v/checker/tests/in_mismatch_type.vv:19:5: error: left operand to `in` does not match: expected `string`, not `rune`
+vlib/v/checker/tests/in_mismatch_type.vv:19:5: error: use `str.contains(substr)` instead of `substr in str`
    17 |         println('dope')
    18 |     }
    19 |     if `a` in s {

vlib/v/pref/default.v

@@ -46,8 +46,10 @@ pub fn (mut p Preferences) fill_with_defaults() {
 			// The file name is just `.v` or `.vsh` or `.*`
 			base = filename
 		}
-		target_dir := if os.is_dir(rpath) { rpath } else { os.dir(rpath) }
+		// target_dir := if os.is_dir(rpath) { rpath } else { os.dir(rpath) }
-		p.out_name = os.join_path(target_dir, base)
+		// If no "-o" was supplied, create the binary in the current
+		// directory. This is the behavior of Go, Clang, GCC, etc.
+		p.out_name = os.join_path(os.getwd(), base)
 		if rpath == '$p.vroot/cmd/v' && os.is_dir('vlib/compiler') {
 			// Building V? Use v2, since we can't overwrite a running
 			// executable on Windows + the precompiled V is more

vlib/v/tests/valgrind/1.strings_and_arrays.v

@@ -348,6 +348,18 @@ fn return_sb_str() string {
 	return sb.str() // sb should be freed, but only after .str() is called
 }
 
+fn parse_header0(s string) ?string {
+	if !s.contains(':') {
+		return error('missing colon in header')
+	}
+	words := s.split_nth(':', 2)
+	return words[0]
+}
+
+fn advanced_optionals() {
+	s := parse_header0('foo:bar') or { return }
+}
+
 fn main() {
 	println('start')
 	simple()
@@ -374,6 +386,7 @@ fn main() {
 	s2 := return_sb_str()
 	// free_map()
 	// loop_map()
+	// advanced_optionals()
 	free_array_except_returned_element()
 	println('end')
 }