https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115230
Bug ID: 115230
Summary: -fvisibility=hidden does not hide Template
Specializations from being exported
Product: gcc
Version: 14.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tanksherman27 at gmail dot com
Target Milestone: ---
Consider the following code:
#include <cstdlib>
template<typename T>
void method(T* src, T* dst, size_t length);
template<>
void method<short>(short* src, short* dst, size_t length) {
}
template<>
void method<int>(int* src, int* dst, size_t length) {
}
Compiled using command line:
g++ -O3 -fvisibility=hidden -std=c++14 -pedantic -Wpedantic -Wall -Werror
templates.cpp
Linked using:
g++ -shared -o libtemplates.so templates.o
When nm is run over it using nm -gDC libtemplates.so, the following symbols are
seen:
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
0000000000001110 T void method<int>(int*, int*, unsigned long)
0000000000001100 T void method<short>(short*, short*, unsigned long)
w __cxa_finalize
w __gmon_start__
T void method<int>(int*, int*, unsigned long) and T void method<short>(short*,
short*, unsigned long) should not be in the symbol table, but they are even
with -fvisibility=hidden.
Strangely, marking both methods with [[gnu::visibility("hidden")]] works and
results in both not being exported.
This was recently observed in the JDK, inside the Java HotSpot VM (see
https://github.com/openjdk/jdk/pull/17955/files#r1498933843)
