Introduce the LeftCurlyCheck with a new message

[Kevin222004]

I have read check documentation:
https://checkstyle.org/config_blocks.html#LeftCurly
I have used latest version of checkstyle https://github.com/checkstyle/checkstyle/releases/download/checkstyle-10.6.0/checkstyle-10.6.0-all.jar
I have executed the cli and showed it below, as cli describes the problem better than 1,000 words

$ cat Test.java
class Test {

    void summation()
    /* comment */ { } // violation

    void multiplication()
    { // violation 
    }

 }

$ cat config.xml 
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
        "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name = "Checker">
    <property name="charset" value="UTF-8"/>

    <module name="TreeWalker">
        <module name="LeftCurly">
         <property name="option" value="eol" />
    </module>
    </module>

</module>

output :- 
kevin@inspiron-15-5510:~/Desktop/check_style$ java -jar checkstyle-10.6.0-all.jar -c config.xml Test.java
Starting audit...
[ERROR] /home/kevin/Desktop/check_style/Test.java:7:5: '{' at column 5 should be on the previous line. [LeftCurly]
Audit done.
Checkstyle ends with 1 errors.

we can make violation like // violation '{' is expected at the end of line so user can decide it where to put
the LeftCurly

1. put '{' on previous line
2. move } to next line

more information #12548 (comment)

Attention: we can introduce new message and migrate to it in few iterations. If current message is used good in some context, we should not change it.

[nrmancuso]

@Kevin222004 please follow issue template.

[Kevin222004]

@nrmancuso updated

[romani]

@Kevin222004 , please use officially released version , you used checkstyle-10.6.0-SNAPSHOT.
this issue should not be dependent on issue to make Check comments aware.

[Kevin222004]

@romani done

[romani]

please update Test.java to have violation.

[Kevin222004]

please update Test.java to have violation.

is it fine

[romani]

Please remove method it confuses.

[Kevin222004]

done

[Kevin222004]

@romani ping

[romani]

All // violation should match to violation in flu output. So there should be single comment // violation

[Kevin222004]

@romani ping

[romani]

please remove from /* comment */ { } // violation trailing comment.
there is no violation here.

remove summation it is not required at all.

---

for:

void multiplication()
    { // violation 
    }

Test.java:7:5: '{' at column 5 should be on the previous line.

{ is technically already at end of line and it is alone. So violation is actually correct.
So we are confused again.

[romani]

@Kevin222004 , do you have any recommendations for doc update
at https://checkstyle.org/property_types.html#LeftCurlyOption

Option	Definition
eol	The brace must always be on the end of the line. For example:# if (condition) {

to make clear that "end of line" means something like "same line as block parent (identifier/expression/declaration)"

[Kevin222004]

{ is technically already at end of the line and it is alone. So violation is actually correct.
So we are confused again.

I am also very confused now about this issue 🙃. that which msg is good. where to show which msg end of line or previous line.

if I rethink this from the beginning,
currently, code(logic) will check whether there is whitespace before { or not.

checkstyle/src/main/java/com/puppycrawl/tools/checkstyle/utils/CommonUtil.java

Line 156 in deda511

public static boolean hasWhitespaceBefore(int index, String line) {

know maybe those who have written that code thought about the logic that there is no code possible between { and
identifier/expression/declaration, in any case, there will be no code there so if { would trail with whitespace then
it is obvious that it is on a new line so we need it on previous line to put { at end of the line where it will be as same as block parent. where the message is looking very good that { should be on the previous line. this is the current logic and situation.

the idea of the new message has begun from #12548 (comment)
from the changes

    void method1 ()
    /* violation not reported */ { } // violation ''{' at column 34 should be on the previous line'

know this is also very weird code to put comment like this if we want to put it { at end of line as same as parent block then i think the message is looking very good `{` is expected at end of line
according to me this is only the situation where we need this new message and i think this will also not violate the google java style rule which checkstyle follow

lastly we can change the entire message should be on previous line as end of line . we also have to change the doc
https://checkstyle.org/config_blocks.html#LeftCurly and https://checkstyle.org/property_types.html#LeftCurlyOption
in this case to explain the user and contributor that what exactly end of line means

[Kevin222004]

@Kevin222004 , do you have any recommendations for doc update at https://checkstyle.org/property_types.html#LeftCurlyOption

Option Definition
eol The brace must always be on the end of the line. For example:# if (condition) {
to make clear that "end of line" means something like "same line as block parent (identifier/expression/declaration)"

yes we have to update this to make it very clear the meaning of end of line and if this pr is approved then https://checkstyle.org/config_blocks.html#LeftCurly we also need to update this to make it very clear the meaning of message end of line or i think in general we have to update it to make the meaning of eol clear

[Kevin222004]

@romani what is your opinion

[Kevin222004]

@romani should i create the minor pr to update it