[PATCH] D150843: [clang][Diagnostics] Refactor printableTextForNextCharacter

[Corentin Jabot via Phabricator via cfe-commits]

cor3ntin added a comment.

Give some time for @tahonermann to have an opportunity to review again, but otherwise this looks good to me. Thanks!



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Comment at: clang/lib/Frontend/TextDiagnostic.cpp:124-128
+  if (CharSize == 1 && llvm::isLegalUTF8Sequence(Begin, End) &&
+      llvm::sys::locale::isPrint(*Begin)) {
+    ++(*I);
+    return std::make_pair(SmallString<16>(Begin, End), true);
+  }
----------------
tbaeder wrote:
> tbaeder wrote:
> > cor3ntin wrote:
> > > tbaeder wrote:
> > > > cor3ntin wrote:
> > > > > this could be simplified : the common case for ascii could be just looking at `isPrint(*Begin);` (which implies  CharSize == 1 and  llvm::isLegalUTF8Sequence(Begin, End))
> > > > > So you could do it before computing CharSize
> > > > This is not true in my testing fwiw.
> > > ```
> > > const unsigned char *Begin = SourceLine.bytes_begin() + *I;
> > > 
> > >   // Fast path for the common ASCII case.
> > >   if (*Begin < 0x80 && llvm::sys::locale::isPrint(*Begin)) {
> > >     ++(*I);
> > >     return std::make_pair(SmallString<16>(Begin, Begin + 1), true);
> > >   }
> > > ```
> > > seems to work fine locally. Note that I'm not sure `*Begin` is always valid - it seems to be, but we might want an assert to check that SourceLine is not empty. 
> > This function is only ever called in a `while (I < SourceLine.size())` loop. I've thought about refactoring this into a helper struct that keeps the index separate from the calling function to simplify callers.
> Oh also, there are two asserts at the beginning of the function to ensure `I` is valid.
you are right, if, `SourceLine` is empty, that first asset would always fire


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https://reviews.llvm.org/D150843