javac rejects canonical constructor when formal parameter name doesn't match the record component name

[Brian Goetz]

On this one, I agree with the compiler and think the spec should be adjusted. 

The reasoning is that I am looking down he road at named parameter invocation, and if the record component names mismatch the canonical ctor param names, that will cause trouble for no benefit.  

Sent from my iPad

> On Dec 24, 2019, at 5:50 AM, Tagir Valeev <amaembo at gmail.com> wrote:
> 
> Hello!
> 
> javac 14-ea+28-1366 rejects the following code:
> 
> record R(int x) {
>  public R(int _x) { this.x = _x; }
> }
> 
> Test.java:2: error: invalid canonical constructor in record R
>  public R(int _x) { this.x = _x; }
>         ^
>  (invalid parameter names in canonical constructor)
> Note: Test.java uses preview language features.
> Note: Recompile with -Xlint:preview for details.
> 
> However, the spec for the records [1] doesn't prohibit such a
> renaming. It says only that "The types of the formal parameters in the
> formal parameter list of the canonical constructor must be identical
> to the declared type of the corresponding record component." The
> formal parameter names are only mentioned in "derived constructor
> signature" definition. However, this definition doesn't prohibit
> anything, to my understanding. So either compiler should be updated to
> allow such a code or spec should be updated to explicitly prohibit it.
> 
> With best regards,
> Tagir Valeev.
> 
> [1] http://cr.openjdk.java.net/~gbierman/jep359/jep359-20191125/specs/records-jls.html#jls-8.10.4