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directive-export.mk revision 1.12 
      1 # $NetBSD: directive-export.mk,v 1.12 2024/06/01 10:06:23 rillig Exp $
      2 #
      3 # Tests for the .export directive.
      4 #
      5 # See also:
      6 #	directive-misspellings.mk
      7 
      8 # TODO: Implementation
      9 
     10 INDIRECT=	indirect
     11 VAR=		value $$ ${INDIRECT}
     12 
     13 # Before 2020-12-13, this unusual expression invoked undefined behavior since
     14 # it accessed out-of-bounds memory via Var_Export -> ExportVar -> MayExport.
     15 .export ${:U }
     16 
     17 # A variable is exported using the .export directive.
     18 # During that, its value is expanded, just like almost everywhere else.
     19 .export VAR
     20 .if ${:!env | grep '^VAR'!} != "VAR=value \$ indirect"
     21 .  error
     22 .endif
     23 
     24 # Undefining a variable that has been exported implicitly removes it from
     25 # the environment of all child processes.
     26 .undef VAR
     27 .if ${:!env | grep '^VAR' || true!} != ""
     28 .  error
     29 .endif
     30 
     31 # Before var.c 1.1117 from 2024-06-01, a plain ".export" without a syntactical
     32 # argument exported all global variables.  This case could be triggered
     33 # unintentionally by writing a line of the form ".export ${VARNAMES}" to a
     34 # makefile, when VARNAMES was an empty list.
     35 # expect+1: warning: .export requires an argument.
     36 .export
     37 
     38 # An empty argument means no additional variables to export.
     39 .export ${:U}
     40 
     41 
     42 # Before a child process is started, whether for the '!=' assignment operator
     43 # or for the ':sh' modifier, all variables that were marked for being exported
     44 # are expanded and then exported.  If expanding such a variable requires
     45 # running a child command, the marked-as-exported variables would need to be
     46 # exported first, ending in an endless loop.  To avoid this endless loop,
     47 # don't export the variables while preparing a child process, see
     48 # ExportVarEnv.
     49 EMPTY_SHELL=	${:sh}
     50 .export EMPTY_SHELL	# only marked for export at this point
     51 _!=		:;:	# Force the variable to be actually exported.
     52 
     53 
     54 # If the '.export' directive exports a variable whose value contains a '$',
     55 # the actual export action is deferred until a subprocess is started, assuming
     56 # that only subprocesses access the environment variables.  The ':localtime'
     57 # modifier depends on the 'TZ' environment variable, without any subprocess.
     58 export TZ=${UTC}
     59 # expect+1: 00:00:00
     60 .info ${%T:L:localtime=86400}
     61 INDIRECT_TZ=	${:UAmerica/Los_Angeles}
     62 TZ=		${INDIRECT_TZ}
     63 .export TZ
     64 # expect+1: 00:00:00
     65 .info ${%T:L:localtime=86400}
     66 _!=	echo 'force exporting the environment variables'
     67 # expect+1: 16:00:00
     68 .info ${%T:L:localtime=86400}
     69 
     70 
     71 all:
     72