diff options
| -rw-r--r-- | llvm/docs/ProgrammersManual.rst | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/llvm/docs/ProgrammersManual.rst b/llvm/docs/ProgrammersManual.rst index 94555d9d4ff..e2cb14b4240 100644 --- a/llvm/docs/ProgrammersManual.rst +++ b/llvm/docs/ProgrammersManual.rst @@ -656,19 +656,21 @@ taken is to report them to the user so that the user can attempt to fix the environment. In this case representing the error as a string makes perfect sense. LLVM provides the ``StringError`` class for this purpose. It takes two arguments: A string error message, and an equivalent ``std::error_code`` for -interoperability: +interoperability. It also provides a ``createStringError`` function to simplify +common usage of this class: .. code-block:: c++ - make_error<StringError>("Bad executable", - make_error_code(errc::executable_format_error")); + // These two lines of code are equivalent: + make_error<StringError>("Bad executable", errc::executable_format_error); + createStringError(errc::executable_format_error, "Bad executable"); If you're certain that the error you're building will never need to be converted to a ``std::error_code`` you can use the ``inconvertibleErrorCode()`` function: .. code-block:: c++ - make_error<StringError>("Bad executable", inconvertibleErrorCode()); + createStringError(inconvertibleErrorCode(), "Bad executable"); This should be done only after careful consideration. If any attempt is made to convert this error to a ``std::error_code`` it will trigger immediate program @@ -677,6 +679,14 @@ interoperability you should look for an existing ``std::error_code`` that you can convert to, and even (as painful as it is) consider introducing a new one as a stopgap measure. +``createStringError`` can take ``printf`` style format specifiers to provide a +formatted message: + +.. code-block:: c++ + + createStringError(errc::executable_format_error, + "Bad executable: %s", FileName); + Interoperability with std::error_code and ErrorOr """"""""""""""""""""""""""""""""""""""""""""""""" |
