108 lines
3.3 KiB
Makefile
108 lines
3.3 KiB
Makefile
# $NetBSD: directive-ifmake.mk,v 1.10 2022/02/09 21:09:24 rillig Exp $
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#
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# Tests for the .ifmake directive, which provides a shortcut for asking
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# whether a certain target is requested to be made from the command line.
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#
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# TODO: Describe why the shortcut may be useful (if it's useful at all),
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# instead of using the more general '.if make(target)'.
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.MAKEFLAGS: first second
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# This is the most basic form.
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.ifmake first
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. info ok: positive condition works
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.else
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. warning positive condition fails
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.endif
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# The '!' is interpreted as 'not'. A possible alternative interpretation of
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# this condition is whether the target named "!first" was requested. To
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# distinguish these cases, see the next test.
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.ifmake !first
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. warning unexpected
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.else
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. info ok: negation works
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.endif
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# See if the exclamation mark really means "not", or if it is just part of
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# the target name. Since it means 'not', the two exclamation marks are
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# effectively ignored, and 'first' is indeed a requested target. If the
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# exclamation mark were part of the name instead, the name would be '!!first',
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# and such a target was not requested to be made.
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.ifmake !!first
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. info ok: double negation works
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.else
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. warning double negation fails
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.endif
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# Multiple targets can be combined using the && and || operators.
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.ifmake first && second
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. info ok: both mentioned
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.else
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. warning && does not work as expected
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.endif
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# Negation also works in complex conditions.
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.ifmake first && !unmentioned
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. info ok: only those mentioned
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.else
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. warning && with ! does not work as expected
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.endif
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# Using the .MAKEFLAGS special dependency target, arbitrary command
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# line options can be added at parse time. This means that it is
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# possible to extend the targets to be made.
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.MAKEFLAGS: late-target
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.ifmake late-target
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. info Targets can even be added at parse time.
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.else
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. info No, targets cannot be added at parse time anymore.
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.endif
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# Numbers are interpreted as numbers, no matter whether the directive is
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# a plain .if or an .ifmake.
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.ifmake 0
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. error
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.endif
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.ifmake 1
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.else
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. error
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.endif
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# A condition that consists of a variable expression only (without any
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# comparison operator) can be used with .if and the other .ifxxx directives.
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.ifmake ${:Ufirst}
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. info ok
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.else
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. error
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.endif
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# As an edge case, a target can actually be named "!first" on the command
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# line. There is no way to define a target of this name though since in a
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# dependency line, a plain '!' is interpreted as a dependency operator.
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.MAKEFLAGS: !edge
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.ifmake edge
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. error
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.endif
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# The '\!edge' in the following condition is parsed as a bare word. For such
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# a bare word, there is no escaping mechanism so the backslash passes through.
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# Since the condition function 'make' accepts a pattern instead of a plain
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# target name, the '\' is finally discarded in Str_Match.
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.ifmake \!edge
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.else
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. error
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.endif
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# In a dependency line, a plain '!' is interpreted as a dependency operator
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# (the other two are ':' and '::'). If the '!' is escaped by a '\', as
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# implemented in ParseDependencyTargetWord, the additional backslash is never
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# removed though. The target name thus becomes '\!edge' instead of the
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# intended '!edge'. Defining a target whose name contains a '!' will either
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# require additional tricks, or it may even be impossible.
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first second unmentioned late-target \!edge:
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: $@
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