* John Calcote wrote on Tue, Oct 27, 2009 at 09:20:44PM CET: > Passing a fully-specified function prototype in the macro is a > reasonable thing to do for the sake of various C++ mangling schemes, > as well as for the sake of other calling conventions that require > the number and/or types of parameters to determine the proper > mangled symbol name. However, passing compiler-specific > calling-convention attributes (e.g., __attribute(stdcall), > __stdcall, __declspec(stdcall), __fastcall, __cdecl, etc.,) will > clearly not work, because they're compiler-specific. Each compiler > (even on the same system!) uses different such keywords to specify > the same symbol attributes. Please take a step back, and try to forget the idea of the configure.ac author passing in a fully specified function prototype (as would be needed for C++ mangling) for the moment. Please also ignore efficiency issues completely for the moment. All of these issues are orthogonal to what I am after, and can be discussed afterwards, when they are not premature optimization. Let's think with the Autoconf implementor hat on. We can change macros. We can let AC_CHECK_LIB tests use any number of different attributes, attribute notation syntaxes of different compilers, and calling conventions denoted by those attributes, *as* *long* *as* each of these are only finitely many, or can be delimited to finitely many by some other decisive tests. In the current scheme, AC_CHECK_LIB only tries to *link* a function call, not to actually run the linked code. There are two aspects here to consider: 1) This might not be a sharp enough test to decide which calling convention is used (i.e., linking may succeed, but running would fail). 2) It might depend upon the function whether a link with the currently tested calling convention works: it might succeed with f1 but fail with f2. Now, I'm not even interested in (1) right now; and I am aware that solving (1) in general is probably a tough problem. All I want to know is: is (2) not a problem, and is there only a finite set of name mangling operations done by ways of C calling convention per compiler, unlike is done for C++? If the only exception to this is the number of arguments that is encoded in the mangled name, then that might still be workable, but then it will definitely not be cheap in the end. Everything else can probably be made pretty cheap, at least if the calling convention is the same for all AC_CHECK_LIB* tests. Thanks, Ralf _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf
