[clang-tidy][abseil-string-find-startswith] Add string_view to default string-like classes

[nicovank]

As per title. A small improvement to this check, string_view should work out of the box.

I am slowly looking into adding an option to this check to recommend C++20's API starts_with, and move it to modernize.
Possibly would like to use it as a codemod on our code.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

Author: Nicolas van Kempen (nicovank)

Changes

As per title. A small improvement to this check, string_view should work out of the box.

I am slowly looking into adding an option to this check to recommend C++20's API starts_with, and move it to modernize.
Possibly would like to use it as a codemod on our code.

---

Full diff: https://github.com/llvm/llvm-project/pull/72283.diff

2 Files Affected:

• (modified) clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp (+4-1)
• (modified) clang-tools-extra/test/clang-tidy/checkers/abseil/string-find-startswith.cpp (+21-2)

diff --git a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
index b36144d1912fce0..d0527cba22a917d 100644
--- a/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
+++ b/clang-tools-extra/clang-tidy/abseil/StringFindStartswithCheck.cpp
@@ -19,11 +19,14 @@ using namespace clang::ast_matchers;
 
 namespace clang::tidy::abseil {
 
+const auto DefaultStringLikeClasses =
+    "::std::basic_string; ::std::basic_string_view";
+
 StringFindStartswithCheck::StringFindStartswithCheck(StringRef Name,
                                                      ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
       StringLikeClasses(utils::options::parseStringList(
-          Options.get("StringLikeClasses", "::std::basic_string"))),
+          Options.get("StringLikeClasses", DefaultStringLikeClasses))),
       IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
                                                utils::IncludeSorter::IS_LLVM),
                       areDiagsSelfContained()),
diff --git a/clang-tools-extra/test/clang-tidy/checkers/abseil/string-find-startswith.cpp b/clang-tools-extra/test/clang-tidy/checkers/abseil/string-find-startswith.cpp
index e51568077eda151..ae8d2daf736e979 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/abseil/string-find-startswith.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/abseil/string-find-startswith.cpp
@@ -1,5 +1,5 @@
 // RUN: %check_clang_tidy %s abseil-string-find-startswith %t -- \
-// RUN:   -config="{CheckOptions: {abseil-string-find-startswith.StringLikeClasses: '::std::basic_string;::basic_string'}}"
+// RUN:   -config="{CheckOptions: {abseil-string-find-startswith.StringLikeClasses: '::std::basic_string;::std::basic_string_view;::basic_string'}}"
 
 using size_t = decltype(sizeof(int));
 
@@ -22,6 +22,21 @@ struct basic_string {
 typedef basic_string<char> string;
 typedef basic_string<wchar_t> wstring;
 
+template <typename C>
+class basic_string_view {
+public:
+  basic_string_view();
+  basic_string_view(const basic_string_view &);
+  basic_string_view(const C *);
+  ~basic_string_view();
+  int find(basic_string_view s, int pos = 0);
+  int find(const C *s, int pos = 0);
+  int find(const C *s, int pos, int n);
+  int find(char c, int pos = 0);
+  static constexpr size_t npos = -1;
+};
+typedef basic_string_view<char> string_view;
+
 struct cxx_string {
   int find(const char *s, int pos = 0);
   int rfind(const char *s, int pos = npos);
@@ -39,7 +54,7 @@ std::string bar();
 
 #define A_MACRO(x, y) ((x) == (y))
 
-void tests(std::string s, global_string s2) {
+void tests(std::string s, global_string s2, std::string_view sv) {
   s.find("a") == 0;
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use absl::StartsWith instead of find() == 0 [abseil-string-find-startswith]
   // CHECK-FIXES: {{^[[:space:]]*}}absl::StartsWith(s, "a");{{$}}
@@ -96,6 +111,10 @@ void tests(std::string s, global_string s2) {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use absl::StartsWith
   // CHECK-FIXES: {{^[[:space:]]*}}absl::StartsWith(s2, "a");{{$}}
 
+  sv.find("a") == 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use absl::StartsWith
+  // CHECK-FIXES: {{^[[:space:]]*}}absl::StartsWith(sv, "a");{{$}}
+
   // expressions that don't trigger the check are here.
   A_MACRO(s.find("a"), 0);
   A_MACRO(s.rfind("a", 0), 0);

[nicovank]

First time with LLVM GitHub PR workflow. Am I supposed to tag potential reviewers? @gribozavr @hokein @njames93

[PiotrZSL]

"I am slowly looking into adding an option to this check to recommend C++20's API starts_with, and move it to modernize.
Possibly would like to use it as a codemod on our code."

Actually best would be to copy this check to performance-use-starts_with (or modernize) or something like this, and restrict it to C++20, and this check restrict to !C++20., But similar case is with ends_with.

[PiotrZSL]

As for this check:

• use string header
• update check documentation (option default and description)
• make sure that documentation is in sync with class documentation
• add release notes entry about improving check to support std::string_view

[PiotrZSL]

documentation, string header, release notes

[nicovank]

Copy this check.

Got it. Thanks for the pointer!

Documentation, string header.

I think I covered everything, had to add a couple of skeletons to that string common header.

[PiotrZSL]

LGTM, once you correct latest comments & CI will pass, fell free to merge.

[nicovank]

Addressed feedback.

I do not have commit access, can you please merge after CI is green?
Assuming GitHub will properly populate information, if not you can use Nicolas van Kempen <[email protected]>.