> On 4 Nov 2019, at 18:12, Akim Demaille <a...@lrde.epita.fr> wrote: > >> Le 4 nov. 2019 à 17:03, Matthew Fernandez <matthew.fernan...@gmail.com> a >> écrit : >> >> The std::less implementation you suggest is to also lexicographically >> compare the filenames themselves? I’m not sure this makes sense, because >> source positions from two different files aren’t really orderable at all. > > The point of defining std::less is to have an easy means to insert positions > in a sorted container, say std::map. Now, the order in itself is well > defined, but my not reflect the order the user would like to see. > > To be clear: I don't have a problem with std::less which I see as an > implementation detail, but operators such as <= and the like are different: > they express a total order that we can't implement easily.
The total order is expressed via std::less in containers such as std::map, with undefined results if not fulfilling the specs for that. > In addition, think of C where you also have main.c that #include "foo.h" > somewhere, which results in main.c:1 (i.e., line 1) < foo.h:1 < ... < > foo.h:42 < ... < main.c:3. Here the files are stacked, and if the nested files are closed after being read, the location pointers are dead. > If we want a total order here, it's actually easy: positions should have a > counter somewhere which is the *total* "offset" since the first byte of the > first file. Or something like that.
