string: fix self-assignment, fixes #222

felixguendling · May 26, 2024 · 14389be · 14389be
1 parent 8255bcd
commit 14389be
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Showing 3 changed files with 31 additions and 0 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -35,6 +35,7 @@ if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR
      -Wno-unsafe-buffer-usage
      -Wno-deprecated-declarations
      -Wno-ctad-maybe-unsupported
+     -Wno-self-assign-overloaded
      -Werror
   )
 elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")

diff --git a/include/cista/containers/string.h b/include/cista/containers/string.h
@@ -137,6 +137,9 @@ struct generic_string {
   }
 
   void move_from(generic_string&& s) noexcept {
+    if (&s == this) {
+      return *this;
+    }
     reset();
     std::memcpy(static_cast<void*>(this), &s, sizeof(*this));
     if constexpr (std::is_pointer_v<Ptr>) {
@@ -151,6 +154,9 @@ struct generic_string {
   }
 
   void copy_from(generic_string const& s) {
+    if (&s == this) {
+      return *this;
+    }
     reset();
     if (s.is_short()) {
       std::memcpy(static_cast<void*>(this), &s, sizeof(s));
@@ -434,11 +440,17 @@ struct basic_string : public generic_string<Ptr> {
   basic_string(basic_string&& o) { base::move_from(std::move(o)); }
 
   basic_string& operator=(basic_string const& o) {
+    if (&o == this) {
+      return;
+    }
     base::set_owning(o.data(), o.size());
     return *this;
   }
 
   basic_string& operator=(basic_string&& o) {
+    if (&o == this) {
+      return;
+    }
     base::move_from(std::move(o));
     return *this;
   }

diff --git a/test/string_test.cc b/test/string_test.cc
@@ -18,6 +18,24 @@ constexpr auto const CORNER_CASE_LONG_16 = "0123456789123456";
 constexpr auto const LONG_STR = "hello world hello world";
 constexpr auto const SHORT_STR = "hello world";
 
+TEST_CASE("self assignment") {
+  // case short string
+  cista::raw::string test_short{"test_short"};
+  std::string output_short_pre{test_short};
+  test_short = test_short;
+  std::string output_short_post{test_short};
+  // test_short is empty now
+  CHECK(output_short_pre == output_short_post);
+
+  // case long string
+  cista::raw::string test_long{"test_long_12345678901234567890123456789012"};
+  std::string output_long_pre{test_long};
+  test_long = test_long;
+  std::string output_long_post{test_long};
+  // test_long is filled with 0x01 now
+  CHECK(output_long_pre == output_long_post);
+}
+
 TEST_CASE("string init") {
   auto s = string{};
   CHECK(!s.is_short());