scanner: remove pos 0 hack which is no longer needed (#10935)

vlib/strings/builder.v

@@ -98,8 +98,8 @@ pub fn (mut b Builder) writeln(s string) {
 	b << byte(`\n`)
 }
 
-// buf == 'hello world'
 // last_n(5) returns 'world'
+// buf == 'hello world'
 pub fn (b &Builder) last_n(n int) string {
 	if n > b.len {
 		return ''
@@ -108,8 +108,8 @@ pub fn (b &Builder) last_n(n int) string {
 	return x.bytestr()
 }
 
-// buf == 'hello world'
 // after(6) returns 'world'
+// buf == 'hello world'
 pub fn (b &Builder) after(n int) string {
 	if n >= b.len {
 		return ''
@@ -133,7 +133,7 @@ pub fn (mut b Builder) str() string {
 	return s
 }
 
-// free - manually free the contents of the buffer
+// free is for manually freeing the contents of the buffer
 [unsafe]
 pub fn (mut b Builder) free() {
 	unsafe { free(b.data) }

vlib/v/scanner/scanner.v

@@ -688,11 +688,6 @@ fn (mut s Scanner) text_scan() token.Token {
 				s.is_inter_end = true
 				s.is_inter_start = false
 			}
-			if s.pos == 0 && next_char == ` ` {
-				// If a single letter name at the start of the file, increment
-				// Otherwise the scanner would be stuck at s.pos = 0
-				s.pos++
-			}
 			return s.new_token(.name, name, name.len)
 		} else if c.is_digit() || (c == `.` && nextc.is_digit()) {
 			// `123`, `.123`

vlib/v/scanner/tests/position_0_err.out

@@ -0,0 +1,5 @@
+vlib/v/scanner/tests/position_0_err.vv:1:1: error: unused variable: `i`
+    1 | i := 'hello'
+      | ^
+    2 | x := 3
+    3 | y := 2

vlib/v/scanner/tests/position_0_err.vv

@@ -0,0 +1,4 @@
+i := 'hello'
+x := 3
+y := 2
+println(x + y)

vlib/v/tests/valgrind/simple_interpolation_script_mode.v

@@ -1,5 +1,4 @@
+// TODO: @medvednikov: autofree on script mode does not work when first variable is on position 0 due to the code in `cgen.v:1115`
 v := 't'
-
 s := '${v}.tmp'
-
 println(s)