================
@@ -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();
----------------
ilya-biryukov 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.
> **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.
https://github.com/llvm/llvm-project/pull/131299
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
