50 lines
1.2 KiB
Makefile
50 lines
1.2 KiB
Makefile
# $NetBSD: opt-env.mk,v 1.4 2022/03/26 13:32:31 rillig Exp $
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#
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# Tests for the -e command line option, which looks up environment variables
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# before those from the global scope. It has no influence on variables from
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# the command line though.
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#
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# This option is required by POSIX.
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# The variable FROM_ENV is defined in ./Makefile.
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.MAKEFLAGS: -e
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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# Try to override the variable; this does not have any effect.
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FROM_ENV= value-from-mk
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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# Try to append to the variable; this also doesn't have any effect.
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FROM_ENV+= appended
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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# The default assignment also cannot change the variable.
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FROM_ENV?= default
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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# Neither can the assignment modifiers.
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.if ${FROM_ENV::=from-condition}
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.endif
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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# Even .undef doesn't work since it only affects the global scope,
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# which is independent from the environment variables.
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.undef FROM_ENV
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.if ${FROM_ENV} != value-from-env
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. error ${FROM_ENV}
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.endif
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all: .PHONY
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