RFR: 8274329: Fix non-portable HotSpot code in MethodMatcher::parse_method_pattern

[Jie Fu]

On Sun, 26 Sep 2021 09:55:00 GMT, Jie Fu <jiefu at openjdk.org> wrote:

> Hi all,
> 
> I tried to build OpenJDK on Cygwin (Windows 2016 + VS2019).
> However, I failed with C4474 and C4778 warnings as below:
> 
> Compiling 100 properties into resource bundles for java.desktop
> Compiling 3038 files for java.base
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): error C2220: the following warning is treated as an error
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4778: 'sscanf' : unterminated format string '%255[*\x01\x02\x03\x04\x05\x06\a\b\n\v\f\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f!"#$%&'*+,-0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\^_`abcdefghijklmnopqrstuvwxyz{|}~\xe2\x82\xac\xe4\xba\x97\xe5\x84\x8e\xe5\x8e\x97%n'
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4474: 'sscanf' : too many arguments passed for format string
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(269): note: placeholders and their parameters expect 1 variadic arguments, but 3 were provided
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4778: 'sscanf' : unterminated format string '%1022[[);/\x01\x02\x03\x04\x05\x06\a\b\n\v\f\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f!"#$%&'*+,-0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\^_`abcdefghijklmnopqrstuvwxyz{|}~\xe2\x82\xac\xe4\xba\x97\xe5\x84\x8e\xe5\x8e%n'
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4474: 'sscanf' : too many arguments passed for format string
> e:\jiefu\ws\jdk\src\hotspot\share\compiler\methodMatcher.cpp(319): note: placeholders and their parameters expect 0 variadic arguments, but 2 were provided
> 
> 
> The failure is caused by non-ASCII chars in the format string of sscanf [1][2], which is non-portable on our Windows platform.
> In fact, these non-ASCII coding also triggers C4819 warning, which had been disabled in JDK-8216154 [3].
> And I also found an article showing that sscanf may fail with non-ASCII in the format string [4].
> 
> So it would be nice to remove these non-ASCII chars  (`\x80 ~ \xef`).
> And I think it's safe to do so.
> 
> This is because:
>  1) There are actually no non-ASCII chars for package/class/method/signature names.
>  2) I don't think there is a use case, in which people will input non-ASCII for `CompileCommand`.
> 
> You may argue that the non-ASCII may be used by the parser itself.
> But I didn't find that usage at all. (Please let me know if I miss something.)
> 
> So I suggest to remove these non-ASCII code to make HotSpot to be more portable.
> And if we do so, we can also remove the only one `PRAGMA_DISABLE_MSVC_WARNING(4819)` [5].
> 
> Testing:
>  - Build tests on Windows
>  - tier1~3 on Linux/x64
> 
> Thanks.
> Best regards,
> Jie
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L269
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L319
> [3] https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-January/032014.html
> [4] https://jeffpar.github.io/kbarchive/kb/047/Q47369/
> [5] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/methodMatcher.cpp#L246

> FWIW, there was some prior discussion here about this code as well: #3107
> 
> tl;dr MSVC uses the system locale's code page to parse this, which must be set to `en-us` to work. From the fact that you are getting these warnings, I guess you have a different locale set (can check with `systeminfo`). See also: https://bugs.openjdk.java.net/browse/JDK-8264425
> 
> Though, I can't comment on the changes in this PR.

Thanks @JornVernee for your comments.

My system local is zh-cn.

But changing the locale isn't acceptable since many of our Apps require zh-cn in our country.

According to the JBS, C4819 warning was first observed with VS2017 and was disabled by JDK-8216154.
Then C4474 and C4778 warnings are triggered with VS2019.
So the code is actually non-portable.

If the non-ascii code is useless, it should be removed to make HotSpot to be more portable.
Then C4819, C4474 and C4778 would disappear.
And OpenJDK can be built without changing the locale setting. 

Thanks.

-------------

PR: https://git.openjdk.java.net/jdk/pull/5704