Bug 53870
| Summary: | C++ undeclares standard math functions like isinf() | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Michael van Elst <mlelstv> |
| Component: | bin | Assignee: | David Schultz <das> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | 5.1-CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
Michael van Elst wrote: > >Description: > The following C++ program does not compile on FreeBSD5.* > > #include <cmath> Add: using namespace std; > void foo() > { > double d; > isinf(d); > } > On Sat, Jun 28, 2003, Artem 'Zazoobr' Ignatjev wrote: > > #include <cmath> > Add: > using namespace std; Thanks, this helps. Can you explain why this is necessary for isinf() but not for functions like sin() ? The only difference seems to be that isinf() happens to implemented as a macro (it used to be a function in FreeBSD4). Greetings, -- ,eM""=. a"-. Michael van Elst dWWMWM" - :GM==; mlelstv@dev.de.cw.net :WWMWMw=--. "W=' cable & wireless 9WWMm==-. "-Wmw-" CABLE & WIRELESS State Changed From-To: open->analyzed Please see the following URL: http://gcc.gnu.org/ml/libstdc++/2003-04/msg00119.html As per above the following hack will work: #include <cmath> void foo() { using namespace std; /* XXX */ double d; isinf(d); } Responsible Changed From-To: freebsd-bugs->kan das@ has been handling some of this, so assign to him. Responsible Changed From-To: kan->das Doh, my bad, meant das, not kan. State Changed From-To: analyzed->closed First of all, if you include <cmath> (or any other new C++ header file) as opposed to <math.h>, the C++ standard says that all the declared symbols from the header file are placed in namespace std. The fact that your example program compiles on some systems without a `using namespace std;' line is a bug. However, it seems that the version of gcc in FreeBSD 6.x re-introduces this bug for backwards compatiblity, so your program compiles once again. |
The following C++ program does not compile on FreeBSD5.* #include <cmath> void foo() { double d; isinf(d); } The error message is: c.cc: In function `void foo()': c.cc:5: error: `isinf' undeclared (first use this function) c.cc:5: error: (Each undeclared identifier is reported only once for each function it appears in.) This is caused by isinf() being a macro defined in math.h which is then undef'd in the cmath header. The compiler _should_ then see the underlying function implementation instead of the macro. The same is true for some other functions declared in the near vicinity: isinf() isnan() signbit() and some others like fpclassify() and isfinite(). The latter however do not exists as functions in libc. The error appeared with the introduction of GCC3.3. Fix: Add prototypes for isinf(), isnan(), signbit() functions to math.h. Add function implementations for the other functions that are only macros. How-To-Repeat: See above