[PATCH] D50862: [clang-tidy] Abseil: faster strsplit delimiter check

[Jonas Toth via Phabricator via cfe-commits]

JonasToth added inline comments.


================
Comment at: clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp:85
+
+  // absl::StrSplit(..., "x") ->  absl::StrSplit(..., 'x')
+  // absl::ByAnyChar("x") -> 'x'
----------------
Maybe you could make these comments into full sentences. I do think its clear what they mean, but the rule is full sentences.

Maybe `Find uses of 'absl::...' to transform them into 'absl::...'.`?


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Comment at: clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp:115
+
+  if (const auto *ByAnyChar = Result.Nodes.getNodeAs<Expr>("ByAnyChar")) {
+    Range = ByAnyChar->getSourceRange();
----------------
You can ellide the braces in this case.


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Comment at: clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp:49
+  // in the character literal.
+  if (Result == R"("'")") {
+    return std::string(R"('\'')");
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deannagarcia wrote:
> JonasToth wrote:
> > The comment suggest, that all single quotes need to be escaped and then further processing happens, but you check on identity to `'` and return the escaped version of it. 
> > That confuses me.
> Does the new comment clear it up?
Yes, thank you.


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Comment at: clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp:54
+  // Now replace the " with '.
+  auto Pos = Result.find_first_of('"');
+  if (Pos == Result.npos)
----------------
deannagarcia wrote:
> JonasToth wrote:
> > This expects at max 2 `"` characters. couldnt there be more?
> The only way this will be run is if the string is a single character, so the only possibility if there are more than 2 " characters is that the character that is the delimiter is actually " which is taken care of in the check. Does that make sense/do you think I need to add a comment about this?
Ok I see, you could add an assertion before this section. Having the precondition checked is always a good thing and usually adds clarity as well :)


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Comment at: clang-tidy/abseil/FasterStrsplitDelimiterCheck.cpp:75
+
+  // string_view passed by value and contructed from string literal.
+  auto StringViewArg =
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deannagarcia wrote:
> JonasToth wrote:
> > What about the `std::string_view`?
> This matcher is only here for the next matcher to check to see if absl::ByAnyChar has been passed in a single character string view and is only necessary because ByAnyChar accepts an absl::string_view so it isn't necessary to make one for std::string_view
Ok.


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Comment at: test/clang-tidy/abseil-faster-strsplit-delimiter.cpp:42
+void SplitDelimiters() {
+  absl::StrSplit("ABC", "A");
+  // CHECK-MESSAGES: [[@LINE-1]]:25: warning: absl::StrSplit()/ByAnyChar()/MaxSplits() called with a string literal consisting of a single character; consider using the more efficient overload accepting a character [abseil-faster-strsplit-delimiter]
----------------
deannagarcia wrote:
> JonasToth wrote:
> > Please add a test, where `"A"` is used as an arbitray function argument (similar to the template case, but without templates involved)
> Can you explain this more/provide an example? 
The testcase i had in mind does not make sense, sorry for noise.


https://reviews.llvm.org/D50862