On 10 April 2017 at 10:41, Toebs Douglass wrote: > On 10/04/17 11:35, Brian Drummond wrote: >> On Mon, 2017-04-10 at 10:36 +0200, Toebs Douglass wrote: > >> For each gcc release for which there exists a >> "contrib/download_prerequisites" script (may not apply to the very >> oldest on this list) > > I looked at this back when I started working on this - more than two > months ago :-) I don't remember now exactly what came of it, but I > think it was something like it was downloading very old versions of the > dependencies. I expect they worked, but it seemed to me more like the > script hadn't been maintained. I didn't trust it, at any rate. The script is actively maintained. It uses versions of those libraries known to work correctly with GCC. >> use that script, to download a known compatible version of all required >> libraries into a known compatible location. >> >> Then (from your build directory) >> ../wherever_my_sources_are/configure my_options >> will find and configure to build the lot. > > Yes - I use this behaviour; I do nothing with the three libs except move > their sources into the GCC source tree. > >> It won't use the latest and greatest version of mpfr etc for each >> compiler release, but it'll use the version that most builds of that >> release were built with, and keep you out of the weeds covering rarely >> trodden paths. > > Hmm. That is interesting. Is it then that GCC builds *normally* use > the oldest possible working version of the dependency libraries? No, they use versions that are known to work well. Those aren't the oldest possible, just ones that work well. > Aren't they missing out on improvements in those libraries, by doing so? GCC doesn't use everything in those libraries so most improvements in them are not relevant to GCC. The things it uses are known to work fine. If GCC starts using a new feature from one of those libraries, or something it uses turns out to have a bug, the required version will be updated appropriately.
