[clang-tools-extra] [clang-tidy] Add readability-string-view-substr check (PR #120055)

[Denis Mikhailov via cfe-commits]

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@@ -0,0 +1,108 @@
+// RUN: %check_clang_tidy %s readability-stringview-substr %t
+
+namespace std {
+template <typename T>
+class basic_string_view {
+public:
+  using size_type = unsigned long;
+  static constexpr size_type npos = -1;
+
+  basic_string_view(const char*) {}
+  basic_string_view substr(size_type pos, size_type count = npos) const { return *this; }
+  void remove_prefix(size_type n) {}
+  void remove_suffix(size_type n) {}
+  size_type length() const { return 0; }
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denzor200 wrote:

Please add `size_type size() const { return 0; }` and unit-tests for it

https://github.com/llvm/llvm-project/pull/120055