RFR: 8310314: Misplaced "unnamed classes are a preview feature and are disabled by default" error

[Jim Laskey]

On Mon, 19 Jun 2023 15:51:13 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> Consider code like:
> 
> $ cat Test.java
> void main() {
>     System.err.println("Hello!");
> }
> 
> 
> Currently, the "unnamed classes are a preview feature and are disabled by default" error is put at the end of the file:
> 
> $ java Test.java
> Test.java:4: error: unnamed classes are a preview feature and are disabled by default.
> 
>   (use --enable-preview to enable unnamed classes)
> 1 error
> error: compilation failed
> 
> 
> This does not seem to be user friendly. It seems to me that putting the error on the first method/variable in the file would be better:
> 
> $ java Test.java
> Test.java:1: error: unnamed classes are a preview feature and are disabled by default.
> void main() {
> ^
>   (use --enable-preview to enable unnamed classes)
> 1 error
> error: compilation failed
> 
> 
> The proposed patch is to simply move the source level check to the place where the top-level method or field is parsed. Calling the method multiple times for a single file should not be a problem - `Log` itself will prevent printing the error multiple times for the same file.

LGTM

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

Marked as reviewed by jlaskey (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14544#pullrequestreview-1486532652