autoconf: Diagnostic Macros

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1 8.3.2 Diagnostic messages from M4sugar
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1 
1 When macros statically diagnose abnormal situations, benign or fatal,
1 they should report them using these macros.  For issuing dynamic issues,
1 i.e., when `configure' is run, see ⇒Printing Messages.
1 
1  -- Macro: m4_assert (EXPRESSION, [EXIT-STATUS = `1'])
1      Assert that the arithmetic EXPRESSION evaluates to non-zero.
1      Otherwise, issue a fatal error, and exit `autom4te' with
1      EXIT-STATUS.
1 
1  -- Macro: m4_errprintn (MESSAGE)
1      Similar to the builtin `m4_errprint', except that a newline is
1      guaranteed after MESSAGE.
1 
1  -- Macro: m4_fatal (MESSAGE)
1      Report a severe error MESSAGE prefixed with the current location,
1      and have `autom4te' die.
1 
1  -- Macro: m4_location
1      Useful as a prefix in a message line.  Short for:
1           __file__:__line__
1 
1  -- Macro: m4_warn (CATEGORY, MESSAGE)
1      Report MESSAGE as a warning (or as an error if requested by the
1      user) if warnings of the CATEGORY are turned on.  If the message
1      is emitted, it is prefixed with the current location, and followed
1      by a call trace of all macros defined via `AC_DEFUN' used to get
1      to the current expansion.  You are encouraged to use standard
1      categories, which currently include:
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1     `all'
1           messages that don't fall into one of the following
1           categories.  Use of an empty CATEGORY is equivalent.
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1     `cross'
1           related to cross compilation issues.
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1     `obsolete'
1           use of an obsolete construct.
1 
1     `syntax'
1           dubious syntactic constructs, incorrectly ordered macro calls.
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