[22] JEP 447: Statements before super(...) (Preview)

[mpalat]

https://openjdk.org/jeps/447
In constructors in the Java programming language, allow statements that do not reference the instance being created to appear before an explicit constructor invocation.

Latest spec changes: https://cr.openjdk.org/~gbierman/jep447/latest/
Will have direct impact on the compiler and friends

The Compiler Support

• [22] JEP 447: Statements before super(...) (Preview) - issue #1637 #2063

[mpalat]

Taking a shot at this - Doing an initial investigation for now.

Random Thoughts:
There is a grammar change as per JLS delta

ConstructorBody:
{ [ExplicitConstructorInvocation] [BlockStatements] }

now becomes

ConstructorBody:
{ [BlockStatements] }
{ [BlockStatements] ExplicitConstructorInvocation [BlockStatements] }

However, in our java.g, the relevant code is:
ConstructorDeclaration ::= ConstructorHeader MethodBody
/.$putCase consumeConstructorDeclaration() ; $break ./

Essentially, the error checking for ExplicitConstructionInvocation is handled later in the pipeline. My initial thought here is that we may not have to change grammar/java.g but rather handle these cases later [yes, adhering to the principle of minimal/no grammar change if possible]

[mpalat]

Taking a shot at this - Doing an initial investigation for now.

Compiler support for this is done via #2063. Any issues found will be addressed via additional PRs. And for the record, was able to do without an explicit grammar change as envisaged earlier.

[mpalat]

IDE support will be done via issue #2083. Closing this.