8367530: The exhaustiveness errors could be improved

make/langtools/tools/propertiesparser/parser/MessageType.java

@@ -83,6 +83,7 @@ public enum SimpleType implements MessageType {
         FILE("file", "File", "java.io"),
         FILE_OBJECT("file object", "JavaFileObject", "javax.tools"),
         PATH("path", "Path", "java.nio.file"),
+        PATTERN("pattern", "PatternDescription", "com.sun.tools.javac.comp.ExhaustivenessComputer"),
         NAME("name", "Name", "com.sun.tools.javac.util"),
         LONG("long", "long", null),
         NUMBER("number", "int", null),

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

@@ -50,6 +50,7 @@
 import static com.sun.tools.javac.code.Kinds.Kind.*;
 import static com.sun.tools.javac.code.TypeTag.BOOLEAN;
 import static com.sun.tools.javac.code.TypeTag.VOID;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.ExhaustivenessResult;
 import com.sun.tools.javac.resources.CompilerProperties.Fragments;
 import static com.sun.tools.javac.tree.JCTree.Tag.*;
 import com.sun.tools.javac.util.JCDiagnostic.Fragment;
@@ -696,9 +697,18 @@ public void visitSwitch(JCSwitch tree) {
             tree.isExhaustive = tree.hasUnconditionalPattern ||
                                 TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases);
             if (exhaustiveSwitch) {
-                tree.isExhaustive |= exhaustiveness.exhausts(tree.selector, tree.cases);
                 if (!tree.isExhaustive) {
-                    log.error(tree, Errors.NotExhaustiveStatement);
+                    ExhaustivenessResult exhaustivenessResult = exhaustiveness.exhausts(tree.selector, tree.cases);
+
+                    tree.isExhaustive = exhaustivenessResult.exhaustive();
+
+                    if (!tree.isExhaustive) {
+                        if (exhaustivenessResult.notExhaustiveDetails().isEmpty()) {
+                            log.error(tree, Errors.NotExhaustiveStatement);
+                        } else {
+                            logNotExhaustiveError(tree.pos(), exhaustivenessResult, Errors.NotExhaustiveStatementDetails);
+                        }
+                    }
                 }
             }
             if (!tree.hasUnconditionalPattern && !exhaustiveSwitch) {
@@ -735,16 +745,37 @@ public void visitSwitchExpression(JCSwitchExpression tree) {
                 TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases)) {
                 tree.isExhaustive = true;
             } else {
-                tree.isExhaustive = exhaustiveness.exhausts(tree.selector, tree.cases);
-            }
+                ExhaustivenessResult exhaustivenessResult = exhaustiveness.exhausts(tree.selector, tree.cases);
+
+                tree.isExhaustive = exhaustivenessResult.exhaustive();
 
-            if (!tree.isExhaustive) {
-                log.error(tree, Errors.NotExhaustive);
+                if (!tree.isExhaustive) {
+                    if (exhaustivenessResult.notExhaustiveDetails().isEmpty()) {
+                        log.error(tree, Errors.NotExhaustive);
+                    } else {
+                        logNotExhaustiveError(tree.pos(), exhaustivenessResult, Errors.NotExhaustiveDetails);
+                    }
+                }
             }
+
             alive = prevAlive;
             alive = alive.or(resolveYields(tree, prevPendingExits));
         }
 
+        private void logNotExhaustiveError(DiagnosticPosition pos,
+                                           ExhaustivenessResult exhaustivenessResult,
+                                           Error errorKey) {
+            List<JCDiagnostic> details =
+                    exhaustivenessResult.notExhaustiveDetails()
+                                       .stream()
+                                       .sorted((pd1, pd2) -> pd1.toString().compareTo(pd2.toString()))
+                                       .map(detail -> diags.fragment(Fragments.NotExhaustiveDetail(detail)))
+                                       .collect(List.collector());
+            JCDiagnostic main = diags.error(null, log.currentSource(), pos, errorKey);
+            JCDiagnostic d = new JCDiagnostic.MultilineDiagnostic(main, details);
+            log.report(d);
+        }
+
         public void visitTry(JCTry tree) {
             ListBuffer<PendingExit> prevPendingExits = pendingExits;
             pendingExits = new ListBuffer<>();

src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties

@@ -40,6 +40,7 @@
 # number            an integer
 # option name       the name of a command line option
 # path              a path
+# patter            a pattern/pattern description
 # profile           a profile name
 # source            a source version number, such as 1.5, 1.6, 1.7, taken from a com.sun.tools.javac.code.Source
 # source version    a source version number, such as 1.5, 1.6, 1.7, taken from a javax.lang.model.SourceVersion
@@ -1476,6 +1477,18 @@ compiler.err.not.exhaustive=\
 compiler.err.not.exhaustive.statement=\
     the switch statement does not cover all possible input values
 
+compiler.err.not.exhaustive.details=\
+    the switch expression does not cover all possible input values\n\
+    missing patterns:
+
+compiler.err.not.exhaustive.statement.details=\
+    the switch statement does not cover all possible input values\n\
+    missing patterns:
+
+# 0: pattern
+compiler.misc.not.exhaustive.detail=\
+    {0}
+
 compiler.err.initializer.must.be.able.to.complete.normally=\
     initializer must be able to complete normally
 

src/jdk.compiler/share/classes/com/sun/tools/javac/util/AbstractDiagnosticFormatter.java

@@ -33,6 +33,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import javax.tools.JavaFileObject;
 
@@ -47,6 +48,9 @@
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Type.CapturedType;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.BindingPattern;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.EnumConstantPattern;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.RecordPattern;
 import com.sun.tools.javac.file.PathFileObject;
 import com.sun.tools.javac.jvm.Profile;
 import com.sun.tools.javac.jvm.Target;
@@ -230,6 +234,18 @@ else if (arg instanceof Tag tag) {
             return messages.getLocalizedString(l, "compiler.misc.tree.tag." +
                                                   StringUtils.toLowerCase(tag.name()));
         }
+        else if (arg instanceof BindingPattern bp) {
+            return formatArgument(d, bp.type(), l) + " _";
+        }
+        else if (arg instanceof RecordPattern rp) {
+            return formatArgument(d, rp.type(), l) +
+                   Arrays.stream(rp.nested())
+                         .map(pd -> formatArgument(d, pd, l))
+                         .collect(Collectors.joining(", ", "(", ")"));
+        }
+        else if (arg instanceof EnumConstantPattern ep) {
+            return formatArgument(d, ep.type(), l) + "." + ep.enumConstant();
+        }
         else {
             return String.valueOf(arg);
         }

src/jdk.compiler/share/classes/com/sun/tools/javac/util/RichDiagnosticFormatter.java

@@ -47,8 +47,12 @@
 import static com.sun.tools.javac.code.TypeTag.*;
 import static com.sun.tools.javac.code.Kinds.*;
 import static com.sun.tools.javac.code.Kinds.Kind.*;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.BindingPattern;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.EnumConstantPattern;
+import com.sun.tools.javac.comp.ExhaustivenessComputer.RecordPattern;
 import static com.sun.tools.javac.util.LayoutCharacters.*;
 import static com.sun.tools.javac.util.RichDiagnosticFormatter.RichConfiguration.*;
+import java.util.Arrays;
 
 /**
  * A rich diagnostic formatter is a formatter that provides better integration
@@ -208,6 +212,7 @@ protected void preprocessDiagnostic(JCDiagnostic diag) {
      * @param arg the argument to be translated
      */
     protected void preprocessArgument(Object arg) {
+        //TODO: preprocess for patterns
         if (arg instanceof Type type) {
             preprocessType(type);
         }
@@ -225,6 +230,17 @@ else if (arg instanceof Iterable<?> iterable && !(arg instanceof Path)) {
                 preprocessArgument(o);
             }
         }
+        else if (arg instanceof BindingPattern bp) {
+            preprocessArgument(bp.type());
+        }
+        else if (arg instanceof RecordPattern rp) {
+            preprocessArgument(rp.type());
+            Arrays.stream(rp.nested())
+                  .forEach(this::preprocessArgument);
+        }
+        else if (arg instanceof EnumConstantPattern ep) {
+            preprocessArgument(ep.type());
+        }
     }
 
     /**

test/langtools/tools/javac/diags/Example.java

@@ -602,9 +602,13 @@ boolean run(PrintWriter out, Set<String> keys, boolean raw, List<String> opts, L
          */
         private static void scanForKeys(JCDiagnostic d, Set<String> keys) {
             keys.add(d.getCode());
-            for (Object o: d.getArgs()) {
-                if (o instanceof JCDiagnostic) {
-                    scanForKeys((JCDiagnostic) o, keys);
+            List<Object> todoArgs = new ArrayList<>(Arrays.asList(d.getArgs()));
+            while (!todoArgs.isEmpty()) {
+                Object o = todoArgs.removeLast();
+                if (o instanceof JCDiagnostic sd) {
+                    scanForKeys(sd, keys);
+                } else if (o instanceof List l) {
+                    todoArgs.addAll(l);
                 }
             }
             for (JCDiagnostic sd: d.getSubdiagnostics())

test/langtools/tools/javac/diags/examples/NotExhaustive.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,6 +22,7 @@
  */
 
 // key: compiler.err.not.exhaustive
+// options: -XDexhaustivityTimeout=0
 
 class NotExhaustive {
     int t(int i) {

test/langtools/tools/javac/diags/examples/NotExhaustiveDetails.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+// key: compiler.err.not.exhaustive.details
+// key: compiler.misc.not.exhaustive.detail
+// options: -XDexhaustivityTimeout=-1
+
+class NotExhaustiveDetails {
+    int t(int i) {
+        return switch (i) {
+            case 0 -> -1;
+        };
+    }
+}

test/langtools/tools/javac/diags/examples/NotExhaustiveStatement.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -22,6 +22,7 @@
  */
 
 // key: compiler.err.not.exhaustive.statement
+// options: -XDexhaustivityTimeout=0
 
 class NotExhaustive {
     void t(Object o) {

test/langtools/tools/javac/diags/examples/NotExhaustiveStatementDetails.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+// key: compiler.err.not.exhaustive.statement.details
+// key: compiler.misc.not.exhaustive.detail
+// options: -XDexhaustivityTimeout=-1
+
+class NotExhaustiveDetails {
+    void t(Object o) {
+        switch (o) {
+            case String s -> System.err.println("String of length: " + s.length());
+        };
+    }
+}

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

@@ -2523,6 +2523,7 @@ private void doTest(Path base, String[] libraryCode, String testCode, boolean st
                              "-Xlint:-preview",
                              "--class-path", libClasses.toString(),
                              "-XDshould-stop.at=FLOW",
+                             "-XDexhaustivityTimeout=0",
                              stopAtFlow ? "-XDshould-stop.ifNoError=FLOW"
                                         : "-XDnoop")
                     .outdir(classes)