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From: austern@apple.com To: gcc-gnats@gcc.gnu.org Subject: c++/8041: Array to pointer conversion in cast expression Date: Wed, 25 Sep 2002 11:26:00 -0000 [thread overview] Message-ID: <20020925182450.13999.qmail@sources.redhat.com> (raw) >Number: 8041 >Category: c++ >Synopsis: Array to pointer conversion in cast expression >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: rejects-legal >Submitter-Id: net >Arrival-Date: Wed Sep 25 11:26:02 PDT 2002 >Closed-Date: >Last-Modified: >Originator: austern@apple.com >Release: 2.96 (Redhat), 3.1, 3.2, 3.3 TOT >Organization: >Environment: Linux >Description: Consider the following file: void foo() { typedef int (&AP)[2][2]; int a[2][2]; #ifdef NEW_STYLE_CAST AP ap = static_cast<AP>(a); #else AP ap = (AP) a; #endif } With all of the versions I listed above: this code compiles without error if -DNEW_STYLE_CAST is on the command line, but omitting it yields this error message: ap.cc:8: cannot convert `int (*)[2]' to `int[2][2]' in converting The reason for the error message is that the compiler is applying the array-to-pointer standard conversion, so the argument to the cast expression is of type int (*)[2], which can't be cast to type AP. I believe the compiler is incorrect in applying that standard conversion for the old-style cast, and that the static_cast behavior is right. (Obviously one of the two must be wrong.) Here's an analysis from William Miller, posted on the committee reflector: 5.2.9p2 says that "static_cast<T>(e)" is well-formed if the declaration "T t(e);" is, and the effect is the same as using "t". In this case, if "int (&t)[2](a)" is well-formed, the static_cast is as well. In other words, it depends on how "a" is declared, but it's not automatically an error. >How-To-Repeat: >Fix: >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2002-09-25 18:26 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-09-25 11:26 austern [this message] 2002-12-19 17:27 bangerth 2003-02-14 19:06 René Møller Fonseca
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