https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70984
Bug ID: 70984 Summary: Templated derived class erroneously allows taking address of private base class member functions Product: gcc Version: 5.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: awise.gcc.bug at gmail dot com Target Milestone: --- Created attachment 38431 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38431&action=edit Preprocessed source code Given a base class: class B { protected: void fprot(); int iprot; private: void fpriv(); int ipriv; }; A normal non-templated derived class appears to honour the visibility of base class members in the way that I'd expect: class A : public B { public: void f() { void (B::*f)(); int i; //f = &B::fprot; - protected in this context //f = &B::fpriv; - private in this context f = &A::fprot; // OK - access to protected base member via public derivation //f = &A::fpriv; - private in this context fprot(); // OK - access to protected base member via public derivation //fpriv(); - private in this context i = iprot; // OK - access to protected base member via public derivation //i = ipriv; - private in this context } }; However, a templated derived class allows the address of the private and protected member functions of the base class to be evaluated when I don't believe it should: template<int N> class C : public B { public: void f() { void (B::*f)(); int i; f = &B::fprot; // Should be an error - protected in this context? f = &B::fpriv; // Should be an error - private in this context? f = &C::fprot; // OK - access to protected base member via public derivation f = &C::fpriv; // Should be an error - private in this context? fprot(); // OK - access to protected base member via public derivation //fpriv(); - private in this context i = iprot; //i = ipriv; - private in this context } }; template class C<42>; I'd expect the visibility to be the same as in the non-templated derived class, above. log of compile invoked as "g++ -v -save-temps -c gcc_bug1.cpp": Using built-in specs. COLLECT_GCC=g++ Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.3.1-14ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 5.3.1 20160413 (Ubuntu 5.3.1-14ubuntu2) COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/5/cc1plus -E -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE gcc_bug1.cpp -mtune=generic -march=x86-64 -fpch-preprocess -fstack-protector-strong -Wformat -Wformat-security -o gcc_bug1.ii ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/5" ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/5/../../../../x86_64-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /usr/include/c++/5 /usr/include/x86_64-linux-gnu/c++/5 /usr/include/c++/5/backward /usr/lib/gcc/x86_64-linux-gnu/5/include /usr/local/include /usr/lib/gcc/x86_64-linux-gnu/5/include-fixed /usr/include/x86_64-linux-gnu /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/5/cc1plus -fpreprocessed gcc_bug1.ii -quiet -dumpbase gcc_bug1.cpp -mtune=generic -march=x86-64 -auxbase gcc_bug1 -version -fstack-protector-strong -Wformat -Wformat-security -o gcc_bug1.s GNU C++ (Ubuntu 5.3.1-14ubuntu2) version 5.3.1 20160413 (x86_64-linux-gnu) compiled by GNU C version 5.3.1 20160413, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C++ (Ubuntu 5.3.1-14ubuntu2) version 5.3.1 20160413 (x86_64-linux-gnu) compiled by GNU C version 5.3.1 20160413, GMP version 6.1.0, MPFR version 3.1.4, MPC version 1.0.3 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: a544146c1c8bd944ae4c4ff6181f339e COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic' '-march=x86-64' as -v --64 -o gcc_bug1.o gcc_bug1.s GNU assembler version 2.26 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.26 COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic' '-march=x86-64'