RFR: JDK-8285932 Implementation of JEP-430 String Templates (Preview)

[ExE Boss]

On Thu, 27 Oct 2022 20:16:14 GMT, Jim Laskey <jlaskey at openjdk.org> wrote:

> Enhance the Java programming language with string templates, which are similar to string literals but contain embedded expressions. A string template is interpreted at run time by replacing each expression with the result of evaluating that expression, possibly after further validation and transformation. This is a [preview language feature and API](http://openjdk.java.net/jeps/12).

src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java line 115:

> 113:      * we do not use all those slots, to let the strategies with MethodHandle
> 114:      * combinators to use some arguments.
> 115:      */

Suggestion:

     *
     * @since 20
     */

src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java line 1058:

> 1056:          * @throws Throwable if fails to prepend value (unusual).
> 1057:          */
> 1058:         long prepend(long lengthCoder, byte[] buffer) throws Throwable;

This method is inherently unsafe, as `StringConcatFactory` uses `Unsafe.allocateUninitializedArray(...)` to construct the `buffer`, the intrinsic implementation of which ***DOESN’T*** zero‑out the memory region occupied by the array, which can contain potentially sensitive data.

--------------------------------------------------------------------------------

The `StringConcatItem` interface should be sealed or at least moved to a `jdk.internal.*` package.

-------------

PR: https://git.openjdk.org/jdk/pull/10889