RFR: 8352645: Add tool support to check order of includes [v2]

[Kim Barrett]

On Wed, 26 Mar 2025 14:23:09 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> This PR adds `test/hotspot/jtreg/sources/SortIncludes.java`, a tool to check that blocks of include statements in C++ files are sorted and that there's at least one blank line between user and sys includes (as per the [style guide](https://github.com/openjdk/jdk/blob/master/doc/hotspot-style.md#source-files)).
>> 
>> By virtue of using `SortedSet`, the tool also removes duplicate includes (e.g. `"compiler/compilerDirectives.hpp"` on line [37](https://github.com/openjdk/jdk/blob/059f190f4b0c7836b89ca2070400529e8d33790b/src/hotspot/share/c1/c1_Compilation.cpp#L37) and line [41](https://github.com/openjdk/jdk/blob/059f190f4b0c7836b89ca2070400529e8d33790b/src/hotspot/share/c1/c1_Compilation.cpp#L41)). Sorting uses lowercased strings so that `_` sorts before letters, preserving the prevailing convention in the code base. I've also updated the style guide to clarify this sort-order.
>> 
>> The tool does nothing about re-ordering blocks of conditional includes vs unconditional includes. I briefly looked into that but it gets very complicated, very quickly. That kind of re-ordering will have to continue to be done manually for now.
>> 
>> I have used the tool to fix the ordering of a subset of HotSpot sources and added a test to keep them sorted. That test can be expanded over time to keep includes sorted in other HotSpot directories.
>> 
>> When `TestIncludesAreSorted.java` fails, it tries to provide actionable advice. For example:
>> 
>> java.lang.RuntimeException: The unsorted includes listed below should be fixable by running:
>> 
>>     java /Users/dnsimon/dev/jdk-jdk/open/test/hotspot/jtreg/sources/SortIncludes.java --update /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/c1 /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/ci /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/compiler /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/jvmci
>> 
>> 	at TestIncludesAreSorted.main(TestIncludesAreSorted.java:80)
>> 	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
>> 	at java.base/java.lang.reflect.Method.invoke(Method.java:565)
>> 	at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:335)
>> 	at java.base/java.lang.Thread.run(Thread.java:1447)
>> Caused by: java.lang.RuntimeException: 36 files with unsorted headers found:
>> 
>> /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/c1/c1_Compilation.cpp
>> /Users/dnsimon/dev/jdk-jdk/open/src/hotspot/share/c1/c1_Runtime1.cpp
>> /Users/dnsimo...
>
> Doug Simon has updated the pull request incrementally with one additional commit since the last revision:
> 
>   drop extra blank lines and preserve rule for first include in .inline.hpp files

Probably we want to eventually apply this to gtests, but there might be additional rules there.  The include of
unittest.hpp is (usually) last, and there may be (or may have been) a technical reason for that.

Applying it to jtreg test support files could also introduce some challenges.  Or at least discover a lot of
non-conforming files.  We might eventually want a mechanism for excluding directories, in addition to an inclusion
list (that might eventually be "all").

These kinds of things can be followups once we have the basic mechanism in place.

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PR Comment: https://git.openjdk.org/jdk/pull/24247#issuecomment-2756881833