Set operations used "1<<n" style shifts, which led to undefined
behavior if the signed shift overflowed. Similarly, the right-hand
side of the operator sometimes used a mix of signed and unsigned
integers that were combined with "&". This patch attempts to provide
a consistent implementation that uses unsigned integers everywhere.
Previously it was not possible to use template arguments in template body as
the symbols were not resolved correctly leading to Error: undeclared
identifier: 'XX', eg.:
template defaultOf[T](t: T): expr = (var d: T; d)
echo defaultOf(1) #<- invalid identifier, but should output 0
The problem comes from the fact that macroOrTmpl[...] is transformed by
semSubscript which is trying to evaluate macroOrTmpl identifier in place. This
is okay for non-generic macros or templates, but wrong for generic ones, that
do not have a chance to receive their generic arguments explicitly specified in
brackets.
Solution:
1. macroOrTmpl[...] where macroOrTmpl is non-generic macro or template, then
macroOrTmpl is evaluated before applying brackets. (as before)
2. macroOrTmpl[...] where macroOrTmpl is generic macro or template, then if:
a. It comes from macroOrTmpl[...](...) call expr (efInCall), then macroOrTmpl
is turned into a symbol (efNoEvaluate) rather than evaluating it in place,
then whole bracket expr is returned to semIndirectOp which transforms it
to proper generic macro or template call with explicit generic arguments.
b. macroOrTmpl[...] does not come from call expr, as above macroOrTmpl is
transformed to symbol, then it is transformed into proper generic macro or
template call with explicit generic arguments and no normal arguments.
