fmt: fix unreasonable wrap after if in if very_long && condition { (fix #15635) (#15995)

vlib/v/checker/str.v

@@ -94,9 +94,7 @@ pub fn (mut c Checker) string_inter_lit(mut node ast.StringInterLiteral) ast.Typ
 				c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
 					node.fmt_poss[i])
 			}
-			// v fmt doesn't format this correctly
+			if c.table.final_sym(typ).kind in [.array, .array_fixed, .struct_, .interface_, .none_, .map, .sum_type]
-			if
-				c.table.final_sym(typ).kind in [.array, .array_fixed, .struct_, .interface_, .none_, .map, .sum_type]
 				&& fmt in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `p`, `b`] {
 				c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
 					node.fmt_poss[i])

vlib/v/fmt/fmt.v

@@ -152,7 +152,8 @@ pub struct RemoveNewLineConfig {
 	imports_buffer bool // Work on f.out_imports instead of f.out
 }
 
-pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) {
+// When the removal action actually occurs, the string of the last line after the removal is returned
+pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) string {
 	mut buffer := if cfg.imports_buffer { unsafe { &f.out_imports } } else { unsafe { &f.out } }
 	mut i := 0
 	for i = buffer.len - 1; i >= 0; i-- {
@@ -160,8 +161,23 @@ pub fn (mut f Fmt) remove_new_line(cfg RemoveNewLineConfig) {
 			break
 		}
 	}
+	if i == buffer.len - 1 {
+		return ''
+	}
 	buffer.go_back(buffer.len - i - 1)
 	f.empty_line = false
+	mut line_len := 0
+	mut last_line_str := []u8{}
+	for i = buffer.len - 1; i >= 0; i-- {
+		ch := buffer.byte_at(i)
+		if ch == `\n` {
+			break
+		}
+		line_len += if ch == `\t` { 4 } else { 1 }
+		last_line_str << ch
+	}
+	f.line_len = line_len
+	return last_line_str.reverse().bytestr()
 }
 
 //=== Specialized write methods ===//
@@ -2181,10 +2197,17 @@ fn (mut f Fmt) write_splitted_infix(conditions []string, penalties []int, ignore
 				f.write_splitted_infix(conds, pens, true, is_cond)
 				continue
 			}
+			mut is_wrap_needed := true
 			if i == 0 {
-				f.remove_new_line()
+				last_line_str := f.remove_new_line().trim_space()
+				if last_line_str in ['if', 'for'] {
+					f.write(' ')
+					is_wrap_needed = false
 				}
+			}
+			if is_wrap_needed {
 				f.writeln('')
+			}
 			f.indent++
 			f.write(c)
 			f.indent--

vlib/v/fmt/tests/infix_expr_expected.vv

@@ -31,3 +31,9 @@ fn main() {
 		}
 	}
 }
+
+if c.table.final_sym(typ).kind in [.array, .array_fixed, .struct_, .interface_, .none_, .map, .sum_type]
+	&& fmt in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `p`, `b`] {
+	c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
+		node.fmt_poss[i])
+}

vlib/v/fmt/tests/infix_expr_input.vv

@@ -22,3 +22,9 @@ fn main() {
 		}
 	}
 }
+
+if c.table.final_sym(typ).kind in [.array, .array_fixed, .struct_, .interface_, .none_, .map, .sum_type]
+	&& fmt in [`E`, `F`, `G`, `e`, `f`, `g`, `d`, `u`, `x`, `X`, `o`, `c`, `p`, `b`] {
+	c.error('illegal format specifier `${fmt:c}` for type `${c.table.get_type_name(ftyp)}`',
+		node.fmt_poss[i])
+}