[cfe-dev] [PATCH] add constant expression evaluation to the AST and fix PR2413
akyrtzi at gmail.com
Sat Jun 14 13:15:53 PDT 2008
Eli Friedman wrote:
> On Sun, Jun 8, 2008 at 7:05 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
>> Attached patch adds some capability to the AST to evaluate constant
>> expressions more general than integer constant expressions. It then
>> uses that capability to remove the hack added for
>> Sema/darwin-align-cast.c, which fixes PR2413.
Having a general way to evaluate constant expressions is a great idea
and very useful for consumers.
doesn't seem to me that it "scales" well. There's going to be a lot of
code duplication between all those functions and there isn't a way for
the consumer to do action based on the type of the constant:
if (expr is integer)
else if (expr is float)
How about having a single "EvaluateConstantExpr" method, that accepts a
structure that can hold all the possible values in a union (APSInt,
APFloat, etc.) plus an enum that can indicate what is the type of the
value returned (vt_int, vt_float, vt_complex, etc) ?
To indicate a non constant expression, it could return a vt_notConstant
enum, or it could be implemented as "TryEvaluateConstantExpr" and return
false in that case.
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