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Diffstat (limited to 'Help/command/message.rst')
-rw-r--r-- | Help/command/message.rst | 120 |
1 files changed, 116 insertions, 4 deletions
diff --git a/Help/command/message.rst b/Help/command/message.rst index c614286..6bc0e4c 100644 --- a/Help/command/message.rst +++ b/Help/command/message.rst @@ -1,13 +1,33 @@ message ------- -Display a message to the user. +Log a message. + +Synopsis +^^^^^^^^ + +.. parsed-literal:: + + `General messages`_ + message([<mode>] "message text" ...) + + `Reporting checks`_ + message(<checkState> "message text" ...) + + +General messages +^^^^^^^^^^^^^^^^ .. code-block:: cmake - message([<mode>] "message to display" ...) + message([<mode>] "message text" ...) + +Record the specified message text in the log. If more than one message +string is given, they are concatenated into a single message with no +separator between the strings. -The optional ``<mode>`` keyword determines the type of message: +The optional ``<mode>`` keyword determines the type of message, which +influences the way the message is handled: ``FATAL_ERROR`` CMake Error, stop processing and generation. @@ -59,12 +79,104 @@ The :manual:`curses interface <ccmake(1)>` shows ``STATUS`` to ``TRACE`` messages one at a time on a status line and other messages in an interactive pop-up box. The ``--log-level`` command-line option to each of these tools can be used to control which messages will be shown. +To make a log level persist between CMake runs, the +:variable:`CMAKE_MESSAGE_LOG_LEVEL` variable can be set instead. +Note that the command line option takes precedence over the cache variable. -Messages of log levels ``NOTICE`` and below will also have each line preceded +Messages of log levels ``NOTICE`` and below will have each line preceded by the content of the :variable:`CMAKE_MESSAGE_INDENT` variable (converted to a single string by concatenating its list items). For ``STATUS`` to ``TRACE`` messages, this indenting content will be inserted after the hyphens. +Messages of log levels ``NOTICE`` and below can also have each line preceded +with context of the form ``[some.context.example]``. The content between the +square brackets is obtained by converting the :variable:`CMAKE_MESSAGE_CONTEXT` +list variable to a dot-separated string. The message context will always +appear before any indenting content but after any automatically added leading +hyphens. By default, message context is not shown, it has to be explicitly +enabled by giving the :manual:`cmake <cmake(1)>` ``--log-context`` +command-line option or by setting the :variable:`CMAKE_MESSAGE_CONTEXT_SHOW` +variable to true. See the :variable:`CMAKE_MESSAGE_CONTEXT` documentation for +usage examples. + CMake Warning and Error message text displays using a simple markup language. Non-indented text is formatted in line-wrapped paragraphs delimited by newlines. Indented text is considered pre-formatted. + + +Reporting checks +^^^^^^^^^^^^^^^^ + +A common pattern in CMake output is a message indicating the start of some +sort of check, followed by another message reporting the result of that check. +For example: + +.. code-block:: cmake + + message(STATUS "Looking for someheader.h") + #... do the checks, set checkSuccess with the result + if(checkSuccess) + message(STATUS "Looking for someheader.h - found") + else() + message(STATUS "Looking for someheader.h - not found") + endif() + +This can be more robustly and conveniently expressed using the ``CHECK_...`` +keyword form of the ``message()`` command: + +.. code-block:: cmake + + message(<checkState> "message" ...) + +where ``<checkState>`` must be one of the following: + + ``CHECK_START`` + Record a concise message about the check about to be performed. + + ``CHECK_PASS`` + Record a successful result for a check. + + ``CHECK_FAIL`` + Record an unsuccessful result for a check. + +When recording a check result, the command repeats the message from the most +recently started check for which no result has yet been reported, then some +separator characters and then the message text provided after the +``CHECK_PASS`` or ``CHECK_FAIL`` keyword. Check messages are always reported +at ``STATUS`` log level. + +Checks may be nested and every ``CHECK_START`` should have exactly one +matching ``CHECK_PASS`` or ``CHECK_FAIL``. +The :variable:`CMAKE_MESSAGE_INDENT` variable can also be used to add +indenting to nested checks if desired. For example: + +.. code-block:: cmake + + message(CHECK_START "Finding my things") + list(APPEND CMAKE_MESSAGE_INDENT " ") + unset(missingComponents) + + message(CHECK_START "Finding partA") + # ... do check, assume we find A + message(CHECK_PASS "found") + + message(CHECK_START "Finding partB") + # ... do check, assume we don't find B + list(APPEND missingComponents B) + message(CHECK_FAIL "not found") + + list(POP_BACK CMAKE_MESSAGE_INDENT) + if(missingComponents) + message(CHECK_FAIL "missing components: ${missingComponents}") + else() + message(CHECK_PASS "all components found") + endif() + +Output from the above would appear something like the following:: + + -- Finding my things + -- Finding partA + -- Finding partA - found + -- Finding partB + -- Finding partB - not found + -- Finding my things - missing components: B |