[clang-tidy] fix PR36489 - respect deduced pointer types from auto as well

Summary:
The cppcoreguidelines-pro-bounds-pointer-arithmetic warns on all occassion where
pointer arithmetic is used, but does not check values where the pointer types
is deduced via ``auto``. This patch adjusts this behaviour and solved
PR36489.

Reviewers: alexfh, aaron.ballman, hokein, ilya-biryukov

Reviewed By: alexfh, aaron.ballman

Subscribers: nemanjai, xazax.hun, kbarton, cfe-commits

Differential Revision: https://reviews.llvm.org/D48717

llvm-svn: 337710

1 files changed, 28 insertions, 1 deletions

diff --git a/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp b/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
index 7cbc6ddf96a..2b7f9233e36 100644
--- a/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
+++ b/clang-tools-extra/test/clang-tidy/cppcoreguidelines-pro-bounds-pointer-arithmetic.cpp
@@ -85,5 +85,32 @@ void okay() {
 
   auto diff = p - q; // OK, result is arithmetic
 
-  for(int ii : a) ; // OK, pointer arithmetic generated by compiler
+  for (int ii : a)
+    ; // OK, pointer arithmetic generated by compiler
+}
+
+// Fix PR36207
+namespace std {
+template <typename CharT>
+struct char_traits {};
+
+template <typename T>
+struct allocator {};
+
+template <typename CharT,
+          typename Traits = char_traits<CharT>,
+          typename Allocator = allocator<CharT>>
+class basic_string {};
+
+template <class CharT, class Traits, class Alloc>
+basic_string<CharT, Traits, Alloc> operator+(const basic_string<CharT, Traits, Alloc> &lhs,
+                                             const CharT *rhs) {}
+
+using string = basic_string<char>;
+} // namespace std
+
+std::string str_generated() {}
+
+void problematic_addition() {
+  std::string status = str_generated() + " is not found";
 }