lg2: support exception conversion
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I4b3cb55c9d03ed04b1f072bf3f5ef98ccffb0eef
diff --git a/docs/structured-logging.md b/docs/structured-logging.md
index 74c3e41..6801279 100644
--- a/docs/structured-logging.md
+++ b/docs/structured-logging.md
@@ -108,7 +108,8 @@
The APIs can handle (and format appropriately) any data of the following
types: signed or unsigned integers, floating point numbers, booleans, strings
-(C-strings, std::strings, or std::string_views), sdbusplus enums, and pointers.
+(C-strings, std::strings, or std::string_views), sdbusplus enums, exceptions,
+and pointers.
The APIs also perform compile-time analysis of the arguments to give descriptive
error messages for incorrect parameters or format flags. Some examples are:
diff --git a/lib/include/phosphor-logging/lg2/conversion.hpp b/lib/include/phosphor-logging/lg2/conversion.hpp
index 4c860d4..b8e0633 100644
--- a/lib/include/phosphor-logging/lg2/conversion.hpp
+++ b/lib/include/phosphor-logging/lg2/conversion.hpp
@@ -47,6 +47,9 @@
template <typename T>
concept sdbusplus_enum = sdbusplus::message::has_convert_from_string_v<T>;
+template <typename T>
+concept exception_type = std::derived_from<std::decay_t<T>, std::exception>;
+
/** Concept listing all of the types we know how to convert into a format
* for logging.
*/
@@ -54,7 +57,7 @@
concept unsupported_log_convert_types =
!(unsigned_integral_except_bool<T> || std::signed_integral<T> ||
std::same_as<bool, T> || std::floating_point<T> || string_like_type<T> ||
- pointer_type<T> || sdbusplus_enum<T>);
+ pointer_type<T> || sdbusplus_enum<T> || exception_type<T>);
/** Any type we do not know how to convert for logging gives a nicer
* static_assert message. */
@@ -215,6 +218,26 @@
reinterpret_cast<uint64_t>(v));
}
+/* Logging conversion for exceptions. */
+template <log_flags... Fs, exception_type V>
+static auto log_convert(const char* h, log_flag<Fs...> f, V&& v)
+{
+ // Compile-time checks for valid formatting flags.
+ prohibit(f, bin);
+ prohibit(f, dec);
+ prohibit(f, field16);
+ prohibit(f, field32);
+ prohibit(f, field64);
+ prohibit(f, field8);
+ prohibit(f, floating);
+ prohibit(f, hex);
+ prohibit(f, signed_val);
+ prohibit(f, unsigned_val);
+
+ // Treat like a string, but get the 'what' from the exception.
+ return std::make_tuple(h, (f | str).value, v.what());
+}
+
/** Class to facilitate walking through the arguments of the `lg2::log` function
* and ensuring correct parameter types and conversion operations.
*/