Reflecting review comments.

Author: lahodaj

make/CompileInterimLangtools.gmk

@@ -49,7 +49,8 @@ TARGETS += $(patsubst %, $(BUILDTOOLS_OUTPUTDIR)/gensrc/%/module-info.java, \
     $(INTERIM_LANGTOOLS_MODULES))
 
 $(eval $(call SetupCopyFiles, COPY_PREVIEW_FEATURES, \
-    FILES := $(TOPDIR)/src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java $(TOPDIR)/src/java.base/share/classes/jdk/internal/javac/NoPreview.java, \
+    FILES := $(TOPDIR)/src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java \
+        $(TOPDIR)/src/java.base/share/classes/jdk/internal/javac/NoPreview.java, \
     DEST := $(BUILDTOOLS_OUTPUTDIR)/gensrc/java.base.interim/jdk/internal/javac/, \
 ))
 

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

@@ -709,7 +709,7 @@ public void visitSwitchExpression(JCSwitchExpression tree) {
                 constants = new HashSet<>();
                 constants.addAll(((ClassSymbol) selectorSym).permitted);
             }
-            boolean coversInput = false;
+            boolean coversInput = tree.hasTotalPattern;
             Liveness prevAlive = alive;
             for (List<JCCase> l = tree.cases; l.nonEmpty(); l = l.tail) {
                 alive = Liveness.ALIVE;
@@ -750,8 +750,8 @@ public void visitSwitchExpression(JCSwitchExpression tree) {
                 }
                 c.completesNormally = alive != Liveness.DEAD;
             }
-            if ((constants == null || !constants.isEmpty()) && !tree.hasTotalPattern &&
-                !coversInput && !TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases)) {
+            if ((constants == null || !constants.isEmpty()) && !coversInput &&
+                !TreeInfo.isErrorEnumSwitch(tree.selector, tree.cases)) {
                 log.error(tree, Errors.NotExhaustive);
             }
             alive = prevAlive;

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

@@ -287,26 +287,28 @@ private void handleSwitch(JCTree tree,
             //int $idx = 0;
             //$RESTART: switch (invokeDynamic typeSwitch($constant, typeof($pattern1), typeof($pattern2), typeof($pattern3))($obj, $idx)) {
             //     case 0:
-            //         if (!(<desugared $pattern1)) { $idx = 1; continue $RESTART; }
+            //         if (!(<desugared $pattern1>)) { $idx = 1; continue $RESTART; }
             //         $stats$
             //     case 1:
-            //         if (!(<desugared $pattern1)) { $idx = 2; continue $RESTART; }
+            //         if (!(<desugared $pattern1>)) { $idx = 2; continue $RESTART; }
             //         $stats$
             //     case 2, -1:
-            //         if (!(<desugared $pattern1)) { $idx = 3; continue $RESTART; }
+            //         if (!(<desugared $pattern1>)) { $idx = 3; continue $RESTART; }
             //         $stats$
             //     case 3:
-            //         if (!(<desugared $pattern1)) { $idx = 4; continue $RESTART; }
+            //         if (!(<desugared $pattern1>)) { $idx = 4; continue $RESTART; }
             //         $stats$
             //}
             //notes:
             //-pattern desugaring performs assignment to the binding variables
             //-the selector is evaluated only once and stored in a temporary variable
             //-typeSwitch bootstrap method can restart matching at specified index. The bootstrap will
             // categorize the input, and return the case index whose type or constant matches the input.
-            // The bootstrap does not evaluate guards, which are injected at the begining of the case's
+            // The bootstrap does not evaluate guards, which are injected at the beginning of the case's
             // statement list, and if the guard fails, the switch is "continued" and matching is
             // restarted from the next index.
+            //-case null is always desugared to case -1, as the typeSwitch bootstrap method will
+            // return -1 when the input is null
             //
             //a special case for switches over enums with pattern case
             //only a single (type) pattern case is valid, which is equivalent

src/jdk.compiler/share/classes/com/sun/tools/javac/tree/JCTree.java

@@ -2238,7 +2238,6 @@ public boolean isPattern() {
     public static class JCBindingPattern extends JCPattern
             implements BindingPatternTree {
         public JCVariableDecl var;
-//        public boolean nullable;
 
         protected JCBindingPattern(JCVariableDecl var) {
             this.var = var;