The link to the License file on the docs/gcc page appears to be broken.

[graichen]

The link is:
https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/COPYING3?view=markup
The response is:
The requested URL /viewcvs/gcc/trunk/gcc/COPYING3 was not found on this server.

[wglambert]

https://gcc.gnu.org/onlinedocs/libstdc++/manual/license.html might be a good replacement link to use

[tianon]

Nice catch! 😅

I think https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/Copying.html is probably a better replacement though (that other link is good, but is specific to libstdc++ instead of all of gcc).