builtin, cgen: fix printing slice of fn call string (#19450)

Author: yuyi98

vlib/builtin/array.v

@@ -530,7 +530,7 @@ pub fn (mut a array) delete_last() {
 // Alternative: Slices can also be made with [start..end] notation
 // Alternative: `.slice_ni()` will always return an array.
 fn (a array) slice(start int, _end int) array {
-	mut end := _end
+	mut end := if _end == 2147483647 { a.len } else { _end } // max_int
 	$if !no_bounds_checking {
 		if start > end {
 			panic('array.slice: invalid slice index (${start} > ${end})')
@@ -565,7 +565,7 @@ fn (a array) slice(start int, _end int) array {
 // This function always return a valid array.
 fn (a array) slice_ni(_start int, _end int) array {
 	// a.flags.clear(.noslices)
-	mut end := _end
+	mut end := if _end == 2147483647 { a.len } else { _end } // max_int
 	mut start := _start
 
 	if start < 0 {

vlib/builtin/string.v

@@ -1037,7 +1037,8 @@ fn (s string) substr2(start int, _end int, end_max bool) string {
 // substr returns the string between index positions `start` and `end`.
 // Example: assert 'ABCD'.substr(1,3) == 'BC'
 [direct_array_access]
-pub fn (s string) substr(start int, end int) string {
+pub fn (s string) substr(start int, _end int) string {
+	end := if _end == 2147483647 { s.len } else { _end } // max_int
 	$if !no_bounds_checking {
 		if start > end || start > s.len || end > s.len || start < 0 || end < 0 {
 			panic('substr(${start}, ${end}) out of bounds (len=${s.len})')
@@ -1061,7 +1062,8 @@ pub fn (s string) substr(start int, end int) string {
 // version of `substr()` that is used in `a[start..end] or {`
 // return an error when the index is out of range
 [direct_array_access]
-pub fn (s string) substr_with_check(start int, end int) !string {
+pub fn (s string) substr_with_check(start int, _end int) !string {
+	end := if _end == 2147483647 { s.len } else { _end } // max_int
 	if start > end || start > s.len || end > s.len || start < 0 || end < 0 {
 		return error('substr(${start}, ${end}) out of bounds (len=${s.len})')
 	}
@@ -1085,7 +1087,7 @@ pub fn (s string) substr_with_check(start int, end int) !string {
 [direct_array_access]
 pub fn (s string) substr_ni(_start int, _end int) string {
 	mut start := _start
-	mut end := _end
+	mut end := if _end == 2147483647 { s.len } else { _end } // max_int
 
 	// borders math
 	if start < 0 {

vlib/v/gen/c/index.v

@@ -69,7 +69,6 @@ fn (mut g Gen) index_range_expr(node ast.IndexExpr, range ast.RangeExpr) {
 	mut tmp_opt := ''
 	mut cur_line := ''
 	mut gen_or := node.or_expr.kind != .absent || node.is_option
-	mut tmp_left := ''
 
 	if sym.kind == .string {
 		if node.is_gated {
@@ -90,15 +89,6 @@ fn (mut g Gen) index_range_expr(node ast.IndexExpr, range ast.RangeExpr) {
 		}
 		g.expr(node.left)
 	} else if sym.kind == .array {
-		if !range.has_high {
-			tmp_left = g.new_tmp_var()
-			tmp_type := g.typ(node.left_type)
-			g.insert_before_stmt('${util.tabs(g.indent)}${tmp_type} ${tmp_left};')
-			// (tmp = expr, array_slice(...))
-			g.write('(${tmp_left} = ')
-			g.expr(node.left)
-			g.write(', ')
-		}
 		if node.is_gated {
 			g.write('array_slice_ni(')
 		} else {
@@ -107,11 +97,7 @@ fn (mut g Gen) index_range_expr(node ast.IndexExpr, range ast.RangeExpr) {
 		if node.left_type.is_ptr() {
 			g.write('*')
 		}
-		if range.has_high {
-			g.expr(node.left)
-		} else {
-			g.write(tmp_left)
-		}
+		g.expr(node.left)
 	} else if sym.kind == .array_fixed {
 		// Convert a fixed array to V array when doing `fixed_arr[start..end]`
 		info := sym.info as ast.ArrayFixed
@@ -156,17 +142,8 @@ fn (mut g Gen) index_range_expr(node ast.IndexExpr, range ast.RangeExpr) {
 	} else if sym.kind == .array_fixed {
 		info := sym.info as ast.ArrayFixed
 		g.write('${info.size}')
-	} else if sym.kind == .array {
-		if node.left_type.is_ptr() {
-			g.write('${tmp_left}->')
-		} else {
-			g.write('${tmp_left}.')
-		}
-		g.write('len)')
 	} else {
-		g.write('(')
-		g.expr(node.left)
-		g.write(').len')
+		g.write('2147483647') // max_int
 	}
 	g.write(')')
 

vlib/v/slow_tests/inout/printing_slice_of_fn_call_string.out

@@ -0,0 +1,2 @@
+Get called
+ello

vlib/v/slow_tests/inout/printing_slice_of_fn_call_string.vv

@@ -0,0 +1,15 @@
+struct Wrapper {
+	element string
+}
+
+fn (instance Wrapper) get() string {
+	println("Get called")
+	return instance.element
+}
+
+fn main() {
+	wrapper := Wrapper{
+		element: "Hello"
+	}
+	println(wrapper.get()[1..])
+}