From 03b7c76b38f680acf6821a1d56ddbca0b23cc787 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Tue, 26 Jul 2022 14:38:50 +0800
Subject: [PATCH] cgen: optimize auto_str_methods of [str:skip] fields (#15227)

---
 vlib/v/gen/c/auto_str_methods.v               | 23 +++++++++----------
 .../inout/printing_struct_with_skip_fields.vv |  4 ++--
 2 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/vlib/v/gen/c/auto_str_methods.v b/vlib/v/gen/c/auto_str_methods.v
index 2278c29ee0..f28076955c 100644
--- a/vlib/v/gen/c/auto_str_methods.v
+++ b/vlib/v/gen/c/auto_str_methods.v
@@ -843,25 +843,23 @@ fn (mut g Gen) gen_str_for_struct(info ast.Struct, styp string, str_fn_name stri
 		fn_builder.writeln('\treturn res;')
 		fn_builder.writeln('}')
 	}
-	// find skip fields
-	mut skip_field_count := 0
-	for field in info.fields {
+	// find `[str: skip]` fields
+	mut field_skips := []int{}
+	for i, field in info.fields {
 		if attr := field.attrs.find_first('str') {
 			if attr.arg == 'skip' {
-				skip_field_count++
+				field_skips << i
 			}
 		}
 	}
-	fn_body.writeln('\tstring res = str_intp( ${(info.fields.len - skip_field_count) * 4 + 3}, _MOV((StrIntpData[]){')
+	fn_body.writeln('\tstring res = str_intp( ${(info.fields.len - field_skips.len) * 4 + 3}, _MOV((StrIntpData[]){')
 	fn_body.writeln('\t\t{_SLIT("$clean_struct_v_type_name{\\n"), 0, {.d_c=0}},')
+	mut is_first := true
 	for i, field in info.fields {
 		// Skip `str:skip` fields
-		if attr := field.attrs.find_first('str') {
-			if attr.arg == 'skip' {
-				continue
-			}
+		if i in field_skips {
+			continue
 		}
-
 		ftyp_noshared := if field.typ.has_flag(.shared_f) {
 			field.typ.deref().clear_flag(.shared_f)
 		} else {
@@ -885,9 +883,10 @@ fn (mut g Gen) gen_str_for_struct(info ast.Struct, styp string, str_fn_name stri
 			prefix = 'C'
 		}
 
-		// first fields doesn't need \n
-		if i == 0 {
+		if is_first {
+			// first field doesn't need \n
 			fn_body.write_string('\t\t{_SLIT0, $c.si_s_code, {.d_s=indents}}, {_SLIT("    $field.name: $ptr_amp$prefix"), 0, {.d_c=0}}, ')
+			is_first = false
 		} else {
 			fn_body.write_string('\t\t{_SLIT("\\n"), $c.si_s_code, {.d_s=indents}}, {_SLIT("    $field.name: $ptr_amp$prefix"), 0, {.d_c=0}}, ')
 		}
diff --git a/vlib/v/tests/inout/printing_struct_with_skip_fields.vv b/vlib/v/tests/inout/printing_struct_with_skip_fields.vv
index 097458e88c..f285067907 100644
--- a/vlib/v/tests/inout/printing_struct_with_skip_fields.vv
+++ b/vlib/v/tests/inout/printing_struct_with_skip_fields.vv
@@ -1,9 +1,9 @@
 struct Foo {
-	name string
 	age  int    [str: skip]
+	name string
 }
 
 fn main() {
-	x := Foo{'Peter', 25}
+	x := Foo{25, 'Peter'}
 	println(x)
 }