================
@@ -2382,14 +2382,20 @@ size_t SourceManager::getDataStructureSizes() const {
SourceManagerForFile::SourceManagerForFile(StringRef FileName,
StringRef Content) {
+ // We copy to `std::string` for Context instead of StringRef because the
+ // SourceManager::getBufferData() works only with null-terminated buffers.
+ // And we still want to keep the API convenient.
+ ContentBuffer = Content.str();
----------------
HazardyKnusperkeks wrote:
> > How about storing a StringRef and assign Content if it ends with a zero,
> > and only perform the copy if it doesn't?
>
> But we cannot check if `StringRef` is null-terminated because given
> `StringRef S`, accessing `S[S.length()]` is UB in the general case. If
> there's a way to do this that's not UB, we could do that.
>
> I think the easiest way to avoid copies would be to switch to `const char *`
> or `std::string` in the APIs to make it explicit we need null-terminated
> strings. That requires a refactoring of the callers, but ends up being as
> efficient as it is now.
Noted.
> > **My IDE (QtCreator) does uses libformat regularly while typing. I would
> > also prefer not to perform copies all over the place.
>
> But what are the actual costs of this particular copy for the overall
> performance of the IDE? I expect it to be negligible, even though I fully
> sympathize with the idea that we want to avoid unnecessary copies. I just
> don't think we should do this at the expense of exposing API that have UB.
I mainly think about my battery, when I code while being mobile.
https://github.com/llvm/llvm-project/pull/131299
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