Document that LLDB_LOG macros use the format_providers.

Differential Revision: https://reviews.llvm.org/D65293

llvm-svn: 367132
This commit is contained in:
Jim Ingham 2019-07-26 17:25:20 +00:00
parent 711556e6a8
commit be4a78af46
1 changed files with 20 additions and 0 deletions

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@ -206,6 +206,26 @@ private:
} // namespace lldb_private
/// The LLDB_LOG* macros defined below are the way to emit log messages.
///
/// Note that the macros surround the arguments in a check for the log
/// being on, so you can freely call methods in arguments without affecting
/// the non-log execution flow.
///
/// If you need to do more complex computations to prepare the log message
/// be sure to add your own if (log) check, since we don't want logging to
/// have any effect when not on.
///
/// However, the LLDB_LOG macro uses the llvm::formatv system (see the
/// ProgrammersManual page in the llvm docs for more details). This allows
/// the use of "format_providers" to auto-format datatypes, and there are
/// already formatters for some of the llvm and lldb datatypes.
///
/// So if you need to do non-trivial formatting of one of these types, be
/// sure to grep the lldb and llvm sources for "format_provider" to see if
/// there is already a formatter before doing in situ formatting, and if
/// possible add a provider if one does not already exist.
#define LLDB_LOG(log, ...) \
do { \
::lldb_private::Log *log_private = (log); \