varname-dot-makeflags.mk revision 1.2
1 1.2 rillig # $NetBSD: varname-dot-makeflags.mk,v 1.2 2023/02/25 06:54:08 rillig Exp $ 2 1.1 rillig # 3 1.1 rillig # Tests for the special .MAKEFLAGS variable, which collects almost all 4 1.1 rillig # command line arguments and passes them on to any child processes via 5 1.1 rillig # the environment variable MAKEFLAGS (without leading '.'). 6 1.2 rillig # 7 1.2 rillig # See also: 8 1.2 rillig # varname-dot-makeoverrides.mk 9 1.2 rillig 10 1.2 rillig all: dollars_stage_0 #spaces_stage_0 dollars_stage_0 append_stage_0 11 1.2 rillig 12 1.1 rillig 13 1.1 rillig # When options are parsed, the option and its argument are appended as 14 1.1 rillig # separate words to .MAKEFLAGS. Special characters in the option argument 15 1.2 rillig # are not quoted though. It seems to have not been necessary since at least 16 1.2 rillig # 1993. 17 1.2 rillig spaces_stage_0: 18 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 19 1.2 rillig @echo "$@: env MAKEFLAGS=<$$MAKEFLAGS>" 20 1.2 rillig @${MAKE} -f ${MAKEFILE} spaces_stage_1 -d00000 -D"VARNAME WITH SPACES" 21 1.2 rillig 22 1.2 rillig # At this point, the 'VARNAME WITH SPACES' is no longer recognizable as a 23 1.2 rillig # single command line argument. In practice, variable names don't contain 24 1.2 rillig # spaces. 25 1.2 rillig spaces_stage_1: 26 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 27 1.2 rillig @echo "$@: env MAKEFLAGS=<$$MAKEFLAGS>" 28 1.2 rillig 29 1.2 rillig # Demonstrate that '$' characters are altered when they are passed on to child 30 1.2 rillig # make processes via MAKEFLAGS. 31 1.2 rillig dollars_stage_0: 32 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 33 1.2 rillig # The '$$$$' gets parsed as a literal '$$', making the actual variable 34 1.2 rillig # value '$${varname}'. 35 1.2 rillig # 36 1.2 rillig # When Main_ExportMAKEFLAGS adds the variable DOLLARS to MAKEFLAGS, it 37 1.2 rillig # first evaluates the variable value, resulting in '${varname}'. 38 1.2 rillig # 39 1.2 rillig # This value is then escaped as '\$\{varname\}', to ensure that the 40 1.2 rillig # variable is later interpreted as a single shell word. 41 1.2 rillig @${MAKE} -f ${MAKEFILE} dollars_stage_1 DOLLARS='$$$${varname}' 42 1.2 rillig 43 1.2 rillig # The environment variable 'MAKEFLAGS' now contains the variable assignment 44 1.2 rillig # 'DOLLARS=\$\{varname\}', including the backslashes. 45 1.2 rillig # 46 1.2 rillig # expect: dollars_stage_1: env MAKEFLAGS=< -r -k DOLLARS=\$\{varname\}> 47 1.2 rillig # 48 1.2 rillig # When Main_ParseArgLine calls Str_Words to parse the flags from MAKEFLAGS, it 49 1.2 rillig # removes the backslashes, resulting in the plain variable assignment 50 1.2 rillig # 'DOLLARS=${varname}'. 51 1.2 rillig dollars_stage_1: 52 1.2 rillig @echo "$@: env MAKEFLAGS=<$$MAKEFLAGS>" 53 1.2 rillig 54 1.2 rillig # At this point, evaluating the environment variable 'MAKEFLAGS' has 55 1.2 rillig # strange side effects, as the string '\$\{varname\}' is interpreted 56 1.2 rillig # as: 57 1.2 rillig # 58 1.2 rillig # \ a single backslash 59 1.2 rillig # $\ the value of the variable named '\' 60 1.2 rillig # {varname\} a literal string 61 1.2 rillig # 62 1.2 rillig # Since the variable name '\' is not defined, the resulting value is 63 1.2 rillig # '\{varname\}'. 64 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 65 1.2 rillig 66 1.2 rillig # The modifier ':q' escapes a '$' in the variable value to '$$', but 67 1.2 rillig # it's too late, as that modifier applies after the expression has 68 1.2 rillig # been evaluated. 69 1.2 rillig @echo '$@: MAKEFLAGS:q=<'${MAKEFLAGS:q}'>' 70 1.2 rillig 71 1.2 rillig # The value of the variable DOLLARS is now '${varname}'. Since there 72 1.2 rillig # is no variable named 'varname', this expression evaluates to ''. 73 1.2 rillig @${MAKE} -f ${MAKEFILE} dollars_stage_2 74 1.2 rillig 75 1.2 rillig # Uncomment these lines to see the above variable expansions in action. 76 1.2 rillig #${:U\\}=backslash 77 1.2 rillig #varname=varvalue 78 1.2 rillig 79 1.2 rillig dollars_stage_2: 80 1.2 rillig @echo "$@: env MAKEFLAGS=<$$MAKEFLAGS>" 81 1.2 rillig @echo '$@: dollars=<'${DOLLARS:Q}'>' 82 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 83 1.2 rillig @${MAKE} -f ${MAKEFILE} dollars_stage_3 84 1.2 rillig 85 1.2 rillig dollars_stage_3: 86 1.2 rillig @echo "$@: env MAKEFLAGS=<$$MAKEFLAGS>" 87 1.2 rillig @echo '$@: dollars=<'${DOLLARS:Uundefined:Q}'>' 88 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 89 1.2 rillig 90 1.2 rillig 91 1.2 rillig # Demonstrates in which exact order the MAKEFLAGS are built together from the 92 1.2 rillig # parent MAKEFLAGS and the flags from the command line, in particular that 93 1.2 rillig # variable assignments are passed at the end, after the options. 94 1.2 rillig append_stage_0: 95 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 96 1.2 rillig @${MAKE} -Dbefore-0 -f ${MAKEFILE} append_stage_1 VAR0=value -Dafter-0 97 1.2 rillig 98 1.2 rillig append_stage_1: 99 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 100 1.2 rillig @${MAKE} -Dbefore-1 -f ${MAKEFILE} append_stage_2 VAR1=value -Dafter-1 101 1.2 rillig 102 1.2 rillig append_stage_2: 103 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 104 1.2 rillig @${MAKE} -Dbefore-2 -f ${MAKEFILE} append_stage_3 VAR2=value -Dafter-2 105 1.2 rillig 106 1.2 rillig append_stage_3: 107 1.2 rillig @echo '$@: MAKEFLAGS=<'${MAKEFLAGS:Q}'>' 108
Indexes created Tue Sep 30 20:09:53 GMT 2025