8268871: Adjust javac to updated exhaustiveness specification #78

lahodaj · 2021-06-16T12:47:22Z

The current updates spec for pattern matching in switch:
http://cr.openjdk.java.net/~gbierman/jep406/jep406-20210608/specs/patterns-switch-jls.html

tweaks the definition of exhaustive switches so that it include handling special types, like intersection types, sealed subclasses of sealed types, like:

sealed abstract class A permits B, C {}
final class B extends A {}
sealed abstract class C extends A permits D, E {}
final class D extends C {}
final class E extends C {}

public class Test {
  public static void main(String[] args) {
     A a = new D();
     System.out.println(
        switch (a) {
           case B x -> "B";
           case D x -> "D";
           case E x -> "E";
        });
  }
}

etc. This patch attempts to tweak javac to work according to this specification. It builds covered types based on what types are covered, i.e. if all subtypes of a sealed type are covered, the sealed type itself is covered, and this is done transitively, so that in the example above, D and E will mark C as covered, and then B and C will mark A as covered, and as the type if a is A, it means the switch is exhaustive.

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Issue

JDK-8268871: Adjust javac to updated exhaustiveness specification

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Vicente Romero (@vicente-romero-oracle - Reviewer)

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bridgekeeper · 2021-06-16T12:48:19Z

👋 Welcome back jlahoda! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2021-06-16T12:49:48Z

@lahodaj The following label will be automatically applied to this pull request:

compiler

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mlbridge · 2021-06-16T12:54:46Z

Webrevs

01: Full - Incremental (a7a61692)
00: Full (b7c067c9)

vicente-romero-oracle · 2021-06-16T16:48:34Z

test/langtools/tools/javac/patterns/Exhaustiveness.java

+    public void testExhaustiveIntersection(Path base) throws Exception {
+        doTest(base,
+               new String[]{"""
+                            package lib;


it will be nice to have additional tests with conditional patterns (total and not) to stress all the possible code paths

Thanks Vicente! I've updated the patch based on your comments in a7a6169 .

What do you think?

Thanks!

vicente-romero-oracle · 2021-06-16T17:08:30Z

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java

+                        }
+
+                        case TYP -> {
+                            for (Type sup : types.directSupertypes(sym.type)) {


just an observation, once a symbol has been processed, there is no need to process it again so you could keep a set of visited symbols to avoid visiting them again. Not a big deal performance wise unless we are switching on a sealed hierarchy with a lot of members I guess > 50 but we know what automatic code generators are capable of :)

vicente-romero-oracle

lgtm

openjdk · 2021-06-24T15:03:52Z

@lahodaj This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8268871: Adjust javac to updated exhaustiveness specification

Reviewed-by: vromero

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 73 new commits pushed to the master branch:

3fb28d3: 8269218: GaloisCounterMode.overlapDetection misses the JDK-8263436 fix again
d3d3b22: 8269265: ProblemList serviceability/sa/TestJmapCoreMetaspace.java with ZGC
0c3fc27: 8268482: compiler/intrinsics/VectorizedMismatchTest.java failed with failed: length in range
a30141d: 8269179: Crash in TestMacroLogicVector::testSubWordBoolean: assert(_base >= VectorMask && _base <= VectorZ) failed: Not a Vector
b474314: 8266854: LibraryCallKit::inline_preconditions_checkIndex modifies control flow even if the intrinsic bailed out
7e96318: 8254571: Erroneous generic type inference in a lambda expression with a checked exception
1b2147a: 8269125: Klass enqueue element size calculation wrong when traceid value cross compress limit
bf70620: 8268961: Parenthesized pattern with guards does not work
8128ca1: 8269066: assert(ZAddress::is_marked(addr)) failed: Should be marked
1323be5: 8269064: Dropped messages of AsyncLogWriter cause memleak
... and 63 more: https://git.openjdk.java.net/jdk17/compare/b18de6cf79e0195736d94b08be67f10ca7c3cd08...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

lahodaj · 2021-06-25T09:51:01Z

/integrate

openjdk · 2021-06-25T09:52:11Z

Going to push as commit 4eb3212.
Since your change was applied there have been 80 commits pushed to the master branch:

44691cc: 8268972: Add default impl for recent new Reporter.print method
7ab1285: 8267610: NPE at at jdk.compiler/com.sun.tools.javac.jvm.Code.emitop
cfa6a99: 8269316: ProblemList vmTestbase/vm/mlvm/mixed/stress/regression/b6969574/INDIFY_Test.java on Linux-X64 -Xcomp
22d8675: 8269315: ProblemList javax/swing/JFileChooser/FileSystemView/SystemIconTest.java on Win-X64
443a79a: 8269314: ProblemList serviceability/dcmd/gc/RunFinalizationTest.java on Win-X64 and linux-aarch64
424cc50: 8269307: ProblemList java/awt/KeyboardFocusmanager/TypeAhead/ButtonActionKeyTest/ButtonActionKeyTest.java on win-x64
63bcd33: 8269246: Scoped ByteBuffer vector access
3fb28d3: 8269218: GaloisCounterMode.overlapDetection misses the JDK-8263436 fix again
d3d3b22: 8269265: ProblemList serviceability/sa/TestJmapCoreMetaspace.java with ZGC
0c3fc27: 8268482: compiler/intrinsics/VectorizedMismatchTest.java failed with failed: length in range
... and 70 more: https://git.openjdk.java.net/jdk17/compare/b18de6cf79e0195736d94b08be67f10ca7c3cd08...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-06-25T09:52:24Z

@lahodaj Pushed as commit 4eb3212.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8268871: Adjust javac to updated exhaustiveness specification

b7c067c

openjdk bot added the rfr label Jun 16, 2021

openjdk bot added the compiler label Jun 16, 2021

vicente-romero-oracle reviewed Jun 16, 2021

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Improving tests, and performance of exhaustive switch detection.

a7a6169

vicente-romero-oracle approved these changes Jun 24, 2021

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openjdk bot added the ready label Jun 24, 2021

openjdk bot closed this Jun 25, 2021

openjdk bot added integrated and removed ready labels Jun 25, 2021

openjdk bot removed the rfr label Jun 25, 2021

8268871: Adjust javac to updated exhaustiveness specification #78

8268871: Adjust javac to updated exhaustiveness specification #78

lahodaj commented Jun 16, 2021 •

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openjdk bot commented Jun 25, 2021

8268871: Adjust javac to updated exhaustiveness specification #78

8268871: Adjust javac to updated exhaustiveness specification #78

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lahodaj commented Jun 16, 2021 • edited by openjdk[bot] bot

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