On Jan 8, 2008 10:34 PM, Joe Buck <[EMAIL PROTECTED]> wrote: > On Tue, Jan 08, 2008 at 11:28:22PM +0200, Ismail Dönmez wrote: > > Hi all, > > > > Looks like gcc 4.3 has some rather inconvenient changes in C++ FE, with the > > latest trunk. Lets see with an example : > > > > [~]> cat test.cpp > > #define foo bar > > #define foo baz > > > > [~]> g++ -c test.cpp > > test.cpp:2:1: error: "foo" redefined > > test.cpp:1:1: error: this is the location of the previous definition > > > > I don't know the reasoning behind this change but this breaks many C++ > > programs unless -fpermissive is used. Why? Because everybody loves to > > install > > their own config.h (Python, libmp4v2 being nice examples) which just > > carelessly #define anything its asked for with ifndef ... endif . > > > > Now flash back to real world: this breaks any C++ application that uses > > Python, libmp4v2, libjpeg and possibly many others. And I think this is a > > real bad behaviour change and I am not sure if its worth all the trouble. > > There's certainly an argument that this change is ill-advised. However, > your statements in the last paragraph aren't true: most quality open > source projects have a "no warnings" rule (or at least try to eliminate > warnings), and most programmers know about #undef. Since people have > already built whole distros with the gcc from the trunk, clearly they > are managing to build C++ applications that use Python, libmp4v2, libjpeg > etc.
Yep, in the worst case we stick a -fpermissive in. See also PR33907 for more obscure cases of the standard. Richard.
