fix build and install gcc-9

.travis.yml

@@ -33,12 +33,6 @@ matrix:
 
     - os: linux
       compiler: g++
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-          packages:
-            - g++-9
       env:
         - CXX_COMPILER=g++-9 CC_COMPILER=gcc-9
 
@@ -123,6 +117,17 @@ install:
       export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:${LLVM_INSTALL}/lib"
     fi
 
+  - |
+    # If linux and gcc-9 install gcc-9.
+    if [[ "${CXX_COMPILER}" == "g++-9" ]]; then
+      wget http://kayari.org/gcc-latest/gcc-latest.deb
+      sudo dpkg -i gcc-latest.deb
+      sudo ln -s /opt/gcc-latest/bin/gcc /usr/bin/gcc-9
+      sudo ln -s /opt/gcc-latest/bin/g++ /usr/bin/g++-9
+      sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 90 --slave /usr/bin/g++ g++ /usr/bin/g++-9
+      sudo ldconfig /opt/gcc-latest/lib64
+    fi
+
 before_script:
   - rm -rf build
   - mkdir -p build

include/nameof.hpp

@@ -167,11 +167,11 @@ template <typename E, E V>
   constexpr auto suffix = sizeof("]") - 1;
 #elif defined(__GNUC__)
   std::string_view name{__PRETTY_FUNCTION__};
-  constexpr auto prefix = sizeof("constexpr std::string_view nameof::detail::nameof_enum_impl() [with E = ") + nameof_type_impl<identity<E>>().length() + sizeof("; V = ");
 #  if __GNUC__ < 9
-  constexpr auto suffix = sizeof("; std::string_view = std::basic_string_view<char>]") - 1;
+  constexpr auto prefix = sizeof("constexpr std::string_view nameof::detail::nameof_enum_impl() [with E = ") + nameof_type_impl<identity<E>>().length() + sizeof("; V = ");
   name.remove_prefix(prefix);
 #  endif
+  constexpr auto suffix = sizeof("; std::string_view = std::basic_string_view<char>]") - 1;
 #elif defined(_MSC_VER)
   std::string_view name{__FUNCSIG__};
   constexpr auto suffix = sizeof(">(void) noexcept") - 1;