http://llvm.org/bugs/show_bug.cgi?id=22254
Bug ID: 22254
Summary: #pragma visibility (GCC generates default, Clang
hidden) if class forward declaration inserted into
visibility push(hidden) section
Product: clang
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: C++
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
Classification: Unclassified
GCC and Clang behaves differently if class forward declaration ends up in
visibility push(hidden) pragma section.
This was causing a linking errors in our software.
Quick discussion in #gcc suggests that this should be Clang issue:
[9:01pm] pinskia: davidlt, mainly because this is a GCC pragma that clang
implements
[9:01pm] davidlt: pinskia: I see
[9:03pm] pinskia: davidlt, and I think the reasoning is that the class B was
default first and then in the declared in the hidden section so the first one
overrides the second
[9:03pm] pinskia: davidlt, like doing:
[9:03pm] pinskia: #pragma GCC visibility push(hidden)
[9:03pm] pinskia: int v;
[9:03pm] pinskia: #pragma GCC visibility pop
[9:04pm] pinskia: int v;
[9:04pm] iains: davidlt: espindola is prob a good person to talk to about this
on #llvm (or here)
Tested with 3.7.0 (trunk, r226371).
class B {
virtual int tangentPlane();
public:
B();
};
class C : B {
public:
C() : B() {}
};
#pragma GCC visibility push(hidden)
class B;
void fn1() {
new C();
}
// GCC
//
// $ readelf --syms -W test_final.o | grep tangentPlane
// 31: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND
_ZN1B12tangentPlaneEv
//
// Clang
//
// $ readelf --syms -W test_final.o | grep tangentPlane
// 25: 0000000000000000 0 NOTYPE GLOBAL HIDDEN UND
_ZN1B12tangentPlaneEv
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