Building on Linux Mint 17.3 (Rosa) with the default version of clang from the package manager: 3.4 fail. It fails because the warning no-unused-local-typedefs is not supported on clang-3.4. By removing the -Wno-unused-local-typedefs from two places in ion/gfx/gfx.gyp it builds successfully.
I think the issue was that -Wno-unused-local-typedef is not supported, but -Wno-unused-local-typedefs is. The latest push uses the latter (this was also broken on Android builds).
Building on Linux Mint 17.3 (Rosa) with the default version of clang from the package manager: 3.4 fail. It fails because the warning no-unused-local-typedefs is not supported on clang-3.4. By removing the -Wno-unused-local-typedefs from two places in ion/gfx/gfx.gyp it builds successfully.