Variable interpolation doesn't work in attribute selector after a `-`

less:

.layout-for-name(@name) {
  [layout-@{name}] {
    box-sizing : border-box;
    display    : flex;
  }
  [layout-@{name}=column] {
    flex-direction : column;
  }
  [layout-@{name}=row] {
    flex-direction : row;
  }
}
.layout-for-name(sm);

expected:

 [layout-sm] {
    box-sizing : border-box;
    display    : flex;
  }
  [layout-sm=column] {
    flex-direction : column;
  }
  [layout-sm=row] {
    flex-direction : row;
  }

currently:

    expected ']' got 'l' in file ...

But Variable interpolation in the attr selector without a - works

less:

.layout-for-name(@name) {
  [@{name}] {
    box-sizing : border-box;
    display    : flex;
  }
  [@{name}=column] {
    flex-direction : column;
  }
  [@{name}=row] {
    flex-direction : row;
  }
}
.layout-for-name(sm);

output:

  [sm] {
    box-sizing : border-box;
    display    : flex;
  }
  [sm=column] {
    flex-direction : column;
  }
  [sm=row] {
    flex-direction : row;
  }

No file or test is named in the report. Start by reproducing both attribute-selector examples through the Less parser, then trace handling of interpolated selectors containing a hyphen; done means the hyphenated case produces the expected selectors without regressing the working case.