RFR: 8303374: Compiler Implementation for Primitive types in patterns, instanceof, and switch (Preview) [v3]

[Maurizio Cimadamore]

On Mon, 2 Oct 2023 14:47:59 GMT, Aggelos Biboudis <abimpoudis at openjdk.org> wrote:

>> This is the first draft of a patch for Primitive types in patterns, instanceof, and switch (Preview).
>> 
>> Draft spec here: https://cr.openjdk.org/~abimpoudis/instanceof/instanceof-20230913/specs/instanceof-jls.html
>
> Aggelos Biboudis has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Merge branch 'master' into primitive-patterns
>  - Implement type pairs to exactnessMethod name
>  - Apply suggestions from code review
>    
>    Co-authored-by: Raffaello Giulietti <raffaello.giulietti at oracle.com>
>  - 8303374: Compiler Implementation for Primitive types in patterns, instanceof, and switch (Preview)

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 5052:

> 5050: 
> 5051:         return (source.isPrimitive() && target.isPrimitive()) &&
> 5052:                 ((source.hasTag(BYTE) && !target.hasTag(CHAR) ||

Does this mean that `byte` -> `char` is not exact? Aren't both integral types, thus invalidating `widening from one integral type to another` ?

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 4154:

> 4152:     public void visitTypeTest(JCInstanceOf tree) {
> 4153:         Type exprtype = attribExpr(tree.expr, env);
> 4154:         if(!allowPrimitivePatterns) {

nit: space missing

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

PR Review Comment: https://git.openjdk.org/jdk/pull/15638#discussion_r1342954914
PR Review Comment: https://git.openjdk.org/jdk/pull/15638#discussion_r1342958314