Hi Shivam, > On 2 Apr 2022, at 17:48, Shivam Gupta <shivam98....@gmail.com> wrote: >
> May I ask why we need to specify --with-gxx-libcxx-include-dir= at > compile/configure time of GCC? The libc++ headers are not part of a base system install (on Darwin they are part of either Xcode or Command Line Tools installations). On other platforms, they will be an optional install. It seems unhelpful to enable an option that will not work (without knowing where to find the headers, -stdlib=libc++ cannot work). For GCC, the default is to use -stdlib=libstdc++, and that is part of the compiler’s install so that it can be located without extra configuration, and it does not require the -stdlib option to work. > While in clang equivalent, -stdlib= doesn't require so. libc++ is the default for clang and is part of the standard compiler distribution (so it can be located without additional configuration). OTOH, I believe that you will find that to make -stdlib=libstdc++ work will generally require some cmake values to point to the GCC installation (On macOS/Darwin there is a default that points to the old apple-gcc-4.2.1 installation [for Darwin11-16], but that is not necessarily the GCC version you would be using there, either). In summary, since neither compiler “knows” where to find the other, some configuration is required in the general case to find the non-native C++ runtime. Iain
