Base: Warn on using ostream<< with std::string*
In most reasonable cases, this is actually a bug. So add a diagnostic.
Test: m
Change-Id: Ib506b45dbdbafcb1893486b08ef13ec8f11d0357
diff --git a/base/include/android-base/logging.h b/base/include/android-base/logging.h
index 548b286..f93c696 100644
--- a/base/include/android-base/logging.h
+++ b/base/include/android-base/logging.h
@@ -438,4 +438,36 @@
} // namespace base
} // namespace android
+namespace std {
+
+// Emit a warning of ostream<< with std::string*. The intention was most likely to print *string.
+//
+// Note: for this to work, we need to have this in a namespace.
+// Note: lots of ifdef magic to make this work with Clang (platform) vs GCC (windows tools)
+// Note: using diagnose_if(true) under Clang and nothing under GCC/mingw as there is no common
+// attribute support.
+// Note: using a pragma because "-Wgcc-compat" (included in "-Weverything") complains about
+// diagnose_if.
+// Note: to print the pointer, use "<< static_cast<const void*>(string_pointer)" instead.
+// Note: a not-recommended alternative is to let Clang ignore the warning by adding
+// -Wno-user-defined-warnings to CPPFLAGS.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wgcc-compat"
+#define OSTREAM_STRING_POINTER_USAGE_WARNING \
+ __attribute__((diagnose_if(true, "Unexpected logging of string pointer", "warning")))
+#else
+#define OSTREAM_STRING_POINTER_USAGE_WARNING /* empty */
+#endif
+inline std::ostream& operator<<(std::ostream& stream, const std::string* string_pointer)
+ OSTREAM_STRING_POINTER_USAGE_WARNING {
+ return stream << static_cast<const void*>(string_pointer);
+}
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+#undef OSTREAM_STRING_POINTER_USAGE_WARNING
+
+} // namespace std
+
#endif // ANDROID_BASE_LOGGING_H