Concrete patterns with newlines have an off by one error for keyword highlighting at the start of a newline

[DavyLandman]

import lang::java::\syntax::Java15;

void main(start[CompilationUnit] cu) {
    if (/(Stm)`if (<Expr _>)
        '   <Stm _> 
        'else 
        '   <Stm _>` := cu) {
        ;
    }
    if (/(Stm)`if (<Expr _>)
        '   <Stm _> 
        ' else 
        '   <Stm _>` := cu) {
        ;
    }
}

The only textual difference is the space in front of the else.

Here is the visual difference:

[jurgenvinju]

Could also be an ambiguity. Use the list ambiguities feature in the ide top find out? If there is ambiguity then highlighting may change depending on "else" being a keyword or not.

[DavyLandman]

nope, not an ambiguity.

(nothing in the ambiguity list, nor after importing the module in the console)