vfmt: fix const comments formatting

[StunxFS]

Fix #20000.

$ cat main.v
const (
	abc = 1 // abc
	def = 2 // def
	ghi = 3 // ghi
)

fn main() {}

$ v fmt main.v
const abc = 1 // abc
const def = 2 // def
const ghi = 3 // ghi

fn main() {}

🤖[deprecated] Generated by Copilot at 0a83026

This pull request enhances the parsing and formatting of constant blocks in V by fixing a syntax error, adding conditional statements, and updating the test files. It affects the files vlib/v/parser/parser.v and vlib/v/fmt/tests/consts_input.vv and vlib/v/fmt/tests/consts_expected.vv.

🤖[deprecated] Generated by Copilot at 0a83026

• Preserve and format inline comments of constant blocks in V (link, link, link, link)
• Add a block of constants with inline comments to consts_input.vv and consts_expected.vv to test the formatting of constant blocks with different delimiters and comments (link, link)
• Modify parse_const_decl in parser.v to append any comments that follow the closing delimiter of a constant block to the end_comments array, and to reset the end_comments array after each constant block (link, link)
• Fix a syntax error in consts_input.vv by removing a trailing comma from the multiline_const array (link)

[spytheman]

That would not work, vfmt has to be changed too, so that it generates source code that will not have to be formatted 2 times in a row.

[spytheman]

I have a patch for that locally, but I can not push it here, github gives me a permission denied error.

[spytheman]

if it will help, here it is as a text diff too:

commit 35bce9c47f91257a0a7c7e7d2fe25f3af674c2f6 (HEAD -> fix_vfmt)
Author: Delyan Angelov <delian66@gmail.com>
Date:   Mon Nov 27 13:32:40 2023 +0200

    fix the `consts_expected.vv` case, make sure to generate source that is invariant over further `v fmt` runs

diff --git vlib/v/fmt/fmt.v vlib/v/fmt/fmt.v
index 0089de380..6994c3bce 100644
--- vlib/v/fmt/fmt.v
+++ vlib/v/fmt/fmt.v
@@ -913,7 +913,7 @@ pub fn (mut f Fmt) const_decl(node ast.ConstDecl) {
        } else {
                ast.Node(ast.NodeError{})
        }
-       for _, field in node.fields {
+       for fidx, field in node.fields {
                if field.comments.len > 0 {
                        if f.should_insert_newline_before_node(ast.Expr(field.comments[0]), prev_field) {
                                f.writeln('')
@@ -936,7 +936,8 @@ pub fn (mut f Fmt) const_decl(node ast.ConstDecl) {
                f.write('= ')
                f.expr(field.expr)
                f.comments(field.end_comments, same_line: true)
-               if node.is_block && field.end_comments.len == 0 {
+               if node.is_block && fidx < node.fields.len - 1 && node.fields.len > 1 {
+                       // old style grouped consts, converted to the new style ungrouped const
                        f.writeln('')
                } else {
                        // Write out single line comments after const expr if present
diff --git vlib/v/fmt/tests/consts_expected.vv vlib/v/fmt/tests/consts_expected.vv
index 699ebbb41..e9a1d1341 100644
--- vlib/v/fmt/tests/consts_expected.vv
+++ vlib/v/fmt/tests/consts_expected.vv
@@ -26,7 +26,9 @@ const i_am_a_very_long_constant_name_so_i_stand_alone_and_my_length_is_over_90_c
 pub const i_am_pub_const = true
 
 const abc = 1 // abc
+
 const def = 2 // def
+
 const ghi = 3 // ghi
 
 fn main() {

[spytheman]

You can test it locally by doing:

echo ">>>>>>>>>>>>>>>>>>>>>>>>  first pass:" && v fmt in.v && echo ">>>>>>>>>>>>>>>>>>>>>>>> second pass:" && v fmt in.v |v fmt

where in.v is:

const (
        abc = 1 // abc
        def = 2 // def
        ghi = 3 // ghi
)

[StunxFS]

You can test it locally by doing:

echo ">>>>>>>>>>>>>>>>>>>>>>>>  first pass:" && v fmt in.v && echo ">>>>>>>>>>>>>>>>>>>>>>>> second pass:" && v fmt in.v |v fmt

where in.v is:

const (
        abc = 1 // abc
        def = 2 // def
        ghi = 3 // ghi
)

Ok, thank you 😁
Locally I had no problems when running the tests 🤔

[spytheman]

for me, without the vfmt patch, either vlib/v/fmt/fmt_keep_test.v failed, or vlib/v/fmt/fmt_test.v failed

[lmptg]

@StunxFS fantastic work! Thanks a lot 💯