hg: jdk/sandbox: Updating javac behavior w.r.t. preview API. Based on darcy's patch.

[jan.lahoda at oracle.com]

Changeset: ee07de0d2c16
Author:    jlahoda
Date:      2019-09-12 17:47 +0200
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/ee07de0d2c16

Updating javac behavior w.r.t. preview API. Based on darcy's patch.

! make/CompileInterimLangtools.gmk
! src/java.base/share/classes/java/lang/String.java
+ src/java.base/share/classes/jdk/internal/PreviewFeature.java
! src/java.base/share/classes/module-info.java
! src/jdk.compiler/share/classes/com/sun/source/tree/CaseTree.java
! src/jdk.compiler/share/classes/com/sun/source/tree/SwitchExpressionTree.java
! src/jdk.compiler/share/classes/com/sun/source/tree/Tree.java
! src/jdk.compiler/share/classes/com/sun/source/tree/TreeVisitor.java
! src/jdk.compiler/share/classes/com/sun/source/tree/YieldTree.java
! src/jdk.compiler/share/classes/com/sun/source/util/SimpleTreeVisitor.java
! src/jdk.compiler/share/classes/com/sun/source/util/TreeScanner.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Flags.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Lint.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Preview.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Symbol.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/code/Symtab.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TypeEnter.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/main/JavaCompiler.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/resources/compiler.properties
! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/JCTree.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeCopier.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/tree/TreeMaker.java
! src/jdk.compiler/share/classes/com/sun/tools/javac/util/Names.java
+ test/langtools/tools/javac/preview/PreviewErrors.java