1 # $NetBSD: dep-var.mk,v 1.13 2025/01/14 21:23:17 rillig Exp $ 2 # 3 # Tests for variable references in dependency declarations. 4 # 5 # Uh oh, this feels so strange that probably nobody uses it. But it seems to 6 # be the only way to reach the lower half of SuffExpandChildren. 7 8 .MAKEFLAGS: -dv 9 10 # In a dependency line, an undefined expressions expands to an empty string. 11 # expect: Var_Parse: ${UNDEF1} (eval) 12 all: ${UNDEF1} 13 14 # Using a double dollar in order to circumvent immediate expression expansion 15 # feels like unintended behavior. At least the manual page says nothing at 16 # all about defined or undefined variables in dependency lines. 17 # 18 # At the point where the expression ${DEF2} is expanded, the variable DEF2 19 # is defined, so everything's fine. 20 all: $${DEF2} a-$${DEF2}-b 21 22 # This variable is neither defined now nor later. 23 all: $${UNDEF3} 24 25 # Try out how many levels of indirection are really expanded in dependency 26 # lines. 27 # 28 # The first level of indirection is the $$ in the dependency line. 29 # When the dependency line is parsed, it is resolved to the string 30 # "${INDIRECT_1}". At this point, the dollar is just an ordinary character, 31 # waiting to be expanded at some later point. 32 # 33 # Later, in SuffExpandChildren, that expression is expanded again by calling 34 # Var_Parse, and this time, the result is the string "1-2-${INDIRECT_2}-2-1". 35 # 36 # This string is not expanded anymore by Var_Parse. But there is another 37 # effect. Now DirExpandCurly comes into play and expands the curly braces 38 # in this filename pattern, resulting in the string "1-2-$INDIRECT_2-2-1". 39 # As of 2020-09-03, the test dir.mk contains further details on this topic. 40 # 41 # Finally, this string is assigned to the local ${.TARGET} variable. This 42 # variable is expanded when the shell command is generated. At that point, 43 # the $I is expanded. Since the variable I is not defined, it expands to 44 # the empty string. This way, the final output is the string 45 # "1-2-NDIRECT_2-2-1", which differs from the actual name of the target. 46 # For exactly this reason, it is not recommended to use dollar signs in 47 # target names. 48 # 49 # The number of actual expansions is way more than one might expect, 50 # therefore this feature is probably not widely used. 51 # 52 all: 1-$${INDIRECT_1}-1 53 INDIRECT_1= 2-$${INDIRECT_2}-2 54 INDIRECT_2= 3-$${INDIRECT_3}-3 55 INDIRECT_3= indirect 56 57 UNDEF1= undef1 58 DEF2= def2 59 60 # Cover the code in SuffExpandChildren that deals with malformed 61 # expressions. 62 # 63 # This seems to be an edge case that never happens in practice, and it would 64 # probably be appropriate to just error out in such a case. 65 # 66 # To trigger this piece of code, the variable name must contain "$)" or "$:" 67 # or "$)" or "$$". Using "$:" does not work since the dependency line is 68 # fully expanded before parsing, therefore any ':' in a target or source name 69 # would be interpreted as a dependency operator instead. 70 all: $$$$) 71 72 # The $$INDIRECT in the following line is treated like the dependency of the 73 # "all" target, that is, the "$$I" is first expanded to "$I", and in a second 74 # round of expansion, the "$I" expands to nothing since the variable "I" is 75 # undefined. 76 # 77 # Since 2020-09-13, this generates a parse error in lint mode (-dL), but not 78 # in normal mode since ParseDependency does not handle any errors after 79 # calling Var_Parse. 80 # expect: Var_Parse: ${:U\$)}: (eval) 81 # expect: Var_Parse: $INDIRECT_2-2-1 $): (parse) 82 # expect: Var_Parse: $): (parse) 83 undef1 def2 a-def2-b 1-2-$$INDIRECT_2-2-1 ${:U\$)}: 84 @echo ${.TARGET:Q} 85 86 .MAKEFLAGS: -d0 87
Indexes created Sat Sep 20 22:09:52 GMT 2025