autoconf: Printing Messages

1 
1 7.5 Printing Messages
1 =====================
1 
1 `configure' scripts need to give users running them several kinds of
1 information.  The following macros print messages in ways appropriate
1 for each kind.  The arguments to all of them get enclosed in shell
1 double quotes, so the shell performs variable and back-quote
1 substitution on them.
1 
1    These macros are all wrappers around the `echo' shell command.  They
11 direct output to the appropriate file descriptor (⇒File Descriptor
 Macros).  `configure' scripts should rarely need to run `echo'
1 directly to print messages for the user.  Using these macros makes it
1 easy to change how and when each kind of message is printed; such
1 changes need only be made to the macro definitions and all the callers
1 change automatically.
1 
11    To diagnose static issues, i.e., when `autoconf' is run, see ⇒
 Diagnostic Macros.
1 
1  -- Macro: AC_MSG_CHECKING (FEATURE-DESCRIPTION)
1      Notify the user that `configure' is checking for a particular
1      feature.  This macro prints a message that starts with `checking '
1      and ends with `...' and no newline.  It must be followed by a call
1      to `AC_MSG_RESULT' to print the result of the check and the
1      newline.  The FEATURE-DESCRIPTION should be something like
1      `whether the Fortran compiler accepts C++ comments' or `for c89'.
1 
1      This macro prints nothing if `configure' is run with the `--quiet'
1      or `--silent' option.
1 
1  -- Macro: AC_MSG_RESULT (RESULT-DESCRIPTION)
1      Notify the user of the results of a check.  RESULT-DESCRIPTION is
1      almost always the value of the cache variable for the check,
1      typically `yes', `no', or a file name.  This macro should follow a
1      call to `AC_MSG_CHECKING', and the RESULT-DESCRIPTION should be
1      the completion of the message printed by the call to
1      `AC_MSG_CHECKING'.
1 
1      This macro prints nothing if `configure' is run with the `--quiet'
1      or `--silent' option.
1 
1  -- Macro: AC_MSG_NOTICE (MESSAGE)
1      Deliver the MESSAGE to the user.  It is useful mainly to print a
1      general description of the overall purpose of a group of feature
1      checks, e.g.,
1 
1           AC_MSG_NOTICE([checking if stack overflow is detectable])
1 
1      This macro prints nothing if `configure' is run with the `--quiet'
1      or `--silent' option.
1 
1  -- Macro: AC_MSG_ERROR (ERROR-DESCRIPTION, [EXIT-STATUS = `$?/1'])
1      Notify the user of an error that prevents `configure' from
1      completing.  This macro prints an error message to the standard
1      error output and exits `configure' with EXIT-STATUS (`$?' by
1      default, except that `0' is converted to `1').  ERROR-DESCRIPTION
1      should be something like `invalid value $HOME for \$HOME'.
1 
1      The ERROR-DESCRIPTION should start with a lower-case letter, and
1      "cannot" is preferred to "can't".
1 
1  -- Macro: AC_MSG_FAILURE (ERROR-DESCRIPTION, [EXIT-STATUS])
1      This `AC_MSG_ERROR' wrapper notifies the user of an error that
1      prevents `configure' from completing _and_ that additional details
1      are provided in `config.log'.  This is typically used when
1      abnormal results are found during a compilation.
1 
1  -- Macro: AC_MSG_WARN (PROBLEM-DESCRIPTION)
1      Notify the `configure' user of a possible problem.  This macro
1      prints the message to the standard error output; `configure'
1      continues running afterward, so macros that call `AC_MSG_WARN'
1      should provide a default (back-up) behavior for the situations
1      they warn about.  PROBLEM-DESCRIPTION should be something like `ln
1      -s seems to make hard links'.
1