[C++ RFC / Patch] PR 31260

Paolo Carlini pcarlini@suse.de
Mon Sep 24 00:10:00 GMT 2007

Mark Mitchell wrote:

>It's true that tsubst_expr, etc., are (unfortunately) not idemopotent;
>you can't safely do tsubst_expr (tsubst_expr (t)).  However, I don't
>understand the logic of the comment that you've (re)-added.  In
>particular, something like:
>  dynamic_cast <S*> (some expression)
>will have type "S*" if "S*" is not a dependent type.  But, that doesn't
>mean that the expression is "at simple as it can get"; there may still
>be substitutions to do in the expression.
>I assume the crash is occurring because of the S3<S2> default argument
>in your test case?  But, how does that relate to the crash that you're
Ok, I'll try to further investigate along the lines that you 
suggested... Of course, if you don't hear again from me about this PR in 
2-3 days you are welcome to look into it yourself, unassigning me: I can 
certainly find other smaller issues to work on. Ah, yes, the issue has 
certainly to do with the default, as shown in Comment #1.


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