compiler: bugfix: constant test in 2 or 3 arg if.

* share/txr/stdlib/compiler.tl (compiler comp-if): The two and
three argument cases assume that if the test is a constant
expression, the consequent "then" should be unconditionally
taken. The correct behavior is to evaluate the constant,
which could yield nil. I checked which library code changes
after this fix, and found that a number of (defset ...)
forms are generating different, shorter code.
This is due to (if ',restpar (if (consp ,restpar) ...))
in defset-expander. The intent there was to eliminate the
inner if code entirely if respar is nil (there is no rest
parameter); due to this bug, the code elimination didn't
happen.  The behavior is nevertheless correct because the
code does nothing if restpar is nil.

0 files changed, 0 insertions, 0 deletions