Force hidden visibility on functions needing distinct static locals
This commit adds a PYBIND11_UNSHARED_STATIC_LOCALS macro that forces a
function to have hidden visibility under gcc and gcc-compatible
compilers. gcc, in particular, needs this to to avoid sharing static
local variables across modules (which happens even under a RTLD_LOCAL
dlopen()!). clang doesn't appear to have this issue, but the forced
visibility on internal pybind functions certainly won't hurt it and icc.
This updates the workaround from #862 to use this rather than the
version-specific template.
diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 5db03e2..cb66e76 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -60,12 +60,10 @@
bool default_holder : 1;
};
-// Store the static internals pointer in a version-specific function so that we're guaranteed it
-// will be distinct for modules compiled for different pybind11 versions. Without this, some
-// compilers (i.e. gcc) can use the same static pointer storage location across different .so's,
-// even though the `get_internals()` function itself is local to each shared object.
-template <int = PYBIND11_VERSION_MAJOR, int = PYBIND11_VERSION_MINOR>
-internals *&get_internals_ptr() { static internals *internals_ptr = nullptr; return internals_ptr; }
+PYBIND11_UNSHARED_STATIC_LOCALS PYBIND11_NOINLINE inline internals *&get_internals_ptr() {
+ static internals *internals_ptr = nullptr;
+ return internals_ptr;
+}
PYBIND11_NOINLINE inline internals &get_internals() {
internals *&internals_ptr = get_internals_ptr();
diff --git a/include/pybind11/common.h b/include/pybind11/common.h
index 240f6d8..518e245 100644
--- a/include/pybind11/common.h
+++ b/include/pybind11/common.h
@@ -68,6 +68,16 @@
# endif
#endif
+// Attribute macro for a function containing one or more static local variables that mustn't share
+// the variable across shared objects (for example, because the value might be incompatible for
+// modules compiled under different pybind versions). This is required under g++ (depending on the
+// specific compiler and linker options), and won't hurt under gcc-compatible compilers:
+#if defined(__GNUG__)
+# define PYBIND11_UNSHARED_STATIC_LOCALS __attribute__ ((visibility("hidden")))
+#else
+# define PYBIND11_UNSHARED_STATIC_LOCALS
+#endif
+
#if defined(_MSC_VER)
# define PYBIND11_NOINLINE __declspec(noinline)
#else