directive-ifmake.mk revision 1.9
1 # $NetBSD: directive-ifmake.mk,v 1.9 2022/01/22 16:23:56 rillig Exp $ 2 # 3 # Tests for the .ifmake directive, which provides a shortcut for asking 4 # whether a certain target is requested to be made from the command line. 5 # 6 # TODO: Describe why the shortcut may be useful (if it's useful at all), 7 # instead of using the more versatile '.if make(target)'. 8 9 .MAKEFLAGS: first second 10 11 # This is the most basic form. 12 .ifmake first 13 . info ok: positive condition works 14 .else 15 . warning positive condition fails 16 .endif 17 18 # The '!' is interpreted as 'not'. A possible alternative interpretation of 19 # this condition is whether the target named "!first" was requested. To 20 # distinguish these cases, see the next test. 21 .ifmake !first 22 . warning unexpected 23 .else 24 . info ok: negation works 25 .endif 26 27 # See if the exclamation mark really means "not", or if it is just part of 28 # the target name. Since it means 'not', the two exclamation marks are 29 # effectively ignored, and 'first' is indeed a requested target. If the 30 # exclamation mark were part of the name instead, the name would be '!!first', 31 # and such a target was not requested to be made. 32 .ifmake !!first 33 . info ok: double negation works 34 .else 35 . warning double negation fails 36 .endif 37 38 # Multiple targets can be combined using the && and || operators. 39 .ifmake first && second 40 . info ok: both mentioned 41 .else 42 . warning && does not work as expected 43 .endif 44 45 # Negation also works in complex conditions. 46 .ifmake first && !unmentioned 47 . info ok: only those mentioned 48 .else 49 . warning && with ! does not work as expected 50 .endif 51 52 # Using the .MAKEFLAGS special dependency target, arbitrary command 53 # line options can be added at parse time. This means that it is 54 # possible to extend the targets to be made. 55 .MAKEFLAGS: late-target 56 .ifmake late-target 57 . info Targets can even be added at parse time. 58 .else 59 . info No, targets cannot be added at parse time anymore. 60 .endif 61 62 # Numbers are interpreted as numbers, no matter whether the directive is 63 # a plain .if or an .ifmake. 64 .ifmake 0 65 . error 66 .endif 67 .ifmake 1 68 .else 69 . error 70 .endif 71 72 # A condition that consists of a variable expression only (without any 73 # comparison operator) can be used with .if and the other .ifxxx directives. 74 .ifmake ${:Ufirst} 75 . info ok 76 .else 77 . error 78 .endif 79 80 81 # As an edge case, a target can actually be named "!first" on the command 82 # line. There is no way to define a target of this name though since in a 83 # dependency line, a plain '!' is interpreted as a dependency operator. 84 85 .MAKEFLAGS: !edge 86 .ifmake edge 87 . error 88 .endif 89 90 # The '\!edge' in the following condition is parsed as a bare word. For such 91 # a bare word, there is no escaping mechanism so the backslash passes through. 92 # Since the condition function 'make' accepts a pattern instead of a plain 93 # target name, the '\' is finally discarded in Str_Match. 94 .ifmake \!edge 95 .else 96 . error 97 .endif 98 99 # In a dependency line, a plain '!' is interpreted as a dependency operator 100 # (the other two are ':' and '::'). If the '!' is escaped by a '\', as 101 # implemented in ParseDependencyTargetWord, the additional backslash is never 102 # removed though. The target name thus becomes '\!edge' instead of the 103 # intended '!edge'. Defining a target whose name contains a '!' will either 104 # require additional tricks, or it may even be impossible. 105 106 first second unmentioned late-target \!edge: 107 : $@ 108
Indexes created Sun Oct 19 02:09:48 GMT 2025