From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 12 May 2022 18:32:32 +0000 (-0400)
Subject: format: add a custom formatter for std::type_info
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=5bb4ff54d92e0a4520f02d08601a0c25f4d2505f;p=lttng-tools.git

format: add a custom formatter for std::type_info

The name() returned by std::type_info is implementation-dependant. In
practice, it is typically the type's mangled name. For GCC and clang, it
is possible to use abi::__cxa_demangle to demangle the name at runtime
while formatting a string.

If this poses any compatibility problem on other platforms, we can
fallback to using name() directly.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ib80babe4039c91ce6fdf6d9a9442c31645a43b08
---

diff --git a/src/common/format.hpp b/src/common/format.hpp
index b49a793b9..73b363408 100644
--- a/src/common/format.hpp
+++ b/src/common/format.hpp
@@ -9,6 +9,9 @@
 
 #include <common/macros.hpp>
 
+#include <string>
+#include <cxxabi.h>
+
 DIAGNOSTIC_PUSH
 DIAGNOSTIC_IGNORE_SUGGEST_ATTRIBUTE_FORMAT
 DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
@@ -16,4 +19,19 @@ DIAGNOSTIC_IGNORE_DUPLICATED_BRANCHES
 #include <vendor/fmt/core.h>
 DIAGNOSTIC_POP
 
+template <>
+struct fmt::formatter<std::type_info> : fmt::formatter<std::string> {
+	template <typename FormatCtx>
+	typename FormatCtx::iterator format(const std::type_info& type_info, FormatCtx& ctx)
+	{
+		int status;
+		auto demangled_name = abi::__cxa_demangle(type_info.name(), nullptr, 0, &status);
+		auto it = status == 0 ? fmt::formatter<std::string>::format(demangled_name, ctx) :
+					      fmt::formatter<std::string>::format(type_info.name(), ctx);
+
+		free(demangled_name);
+		return it;
+	}
+};
+
 #endif /* LTTNG_FORMAT_H */