[libcxx-commits] [libcxx] [libc++][string] Assert resize_and_overwrite operation returns integer-like type (PR #162030)

[A. Jiang via libcxx-commits]

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@@ -77,17 +78,35 @@ constexpr bool test() {
   return true;
 }
 
-void test_value_categories() {
+constexpr bool test_value_categories() {
   std::string s;
   s.resize_and_overwrite(10, [](char*&&, std::size_t&&) { return 0; });
   LIBCPP_ASSERT(is_string_asan_correct(s));
   s.resize_and_overwrite(10, [](char* const&, const std::size_t&) { return 0; });
   LIBCPP_ASSERT(is_string_asan_correct(s));
   struct RefQualified {
-    int operator()(char*, std::size_t) && { return 0; }
+    constexpr int operator()(char*, std::size_t) && { return 0; }
   };
   s.resize_and_overwrite(10, RefQualified{});
   LIBCPP_ASSERT(is_string_asan_correct(s));
+  return true;
+}
+
+template <typename T>
+struct TestIntegerLikeReturnTypes {
+  constexpr void operator()() {
+    std::string s;
+    s.resize_and_overwrite(10, [](char* p, std::size_t n) -> T {
+      std::fill(p, p + n, 'f');
+      return n;
+    });
+    assert(s.size() == 10);
+  }
+};
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frederick-vs-ja wrote:

We can inline this into the lambda body used in `types::for_each`.

https://github.com/llvm/llvm-project/pull/162030