diff options
Diffstat (limited to 'unit-tests/cond-func-empty.mk')
| -rw-r--r-- | unit-tests/cond-func-empty.mk | 43 |
1 files changed, 26 insertions, 17 deletions
diff --git a/unit-tests/cond-func-empty.mk b/unit-tests/cond-func-empty.mk index f93b45895e6e..f43d99bf92c5 100644 --- a/unit-tests/cond-func-empty.mk +++ b/unit-tests/cond-func-empty.mk @@ -1,11 +1,10 @@ -# $NetBSD: cond-func-empty.mk,v 1.8 2020/09/23 08:11:28 rillig Exp $ +# $NetBSD: cond-func-empty.mk,v 1.10 2020/11/15 14:07:53 rillig Exp $ # # Tests for the empty() function in .if conditions, which tests a variable # expression for emptiness. # # Note that the argument in the parentheses is indeed a variable name, -# optionally followed by variable modifiers. This is like the defined() -# function. +# optionally followed by variable modifiers. # .undef UNDEF @@ -25,13 +24,15 @@ WORD= word . error .endif -# The :S modifier replaces the empty value with an actual word, and -# after that the expression is no longer empty. Because the variable -# was undefined in the first place, the expression has the flag VAR_JUNK -# but not VAR_KEEP, therefore it is still considered undefined. -# Only very few variable modifiers turn an undefined variable expression -# into a defined variable expression. The :U and :D modifiers belong to -# that group, but :S doesn't (see VAR_KEEP). +# The :S modifier replaces the empty value with an actual word. The +# expression is now no longer empty, but it is still possible to see whether +# the expression was based on an undefined variable. The expression has the +# flag VEF_UNDEF. +# +# The expression does not have the flag VEF_DEF though, therefore it is still +# considered undefined. Yes, indeed, undefined but not empty. There are a +# few variable modifiers that turn an undefined expression into a defined +# expression, among them :U and :D, but not :S. # # XXX: This is hard to explain to someone who doesn't know these # implementation details. @@ -49,13 +50,14 @@ WORD= word .endif # And now to the surprising part. Applying the following :S modifier to the -# undefined variable makes it non-empty, but the marker VAR_JUNK is preserved -# nevertheless. The :U modifier that follows only looks at VAR_JUNK to decide -# whether the variable is defined or not. This kind of makes sense since the -# :U modifier tests the _variable_, not the _expression_. +# undefined expression makes it non-empty, but the marker VEF_UNDEF is +# preserved nevertheless. The :U modifier that follows only looks at the +# VEF_UNDEF flag to decide whether the variable is defined or not. This kind +# of makes sense since the :U modifier tests the _variable_, not the +# _expression_. # -# But since the variable was undefined to begin with, the fallback value is -# used in this expression. +# But since the variable was undefined to begin with, the fallback value from +# the :U modifier is used in this expression. # .if ${UNDEF:S,^$,value,W:Ufallback} != "fallback" . error @@ -128,7 +130,7 @@ ${:U }= space # If everything goes well, the argument expands to "WORD", and that variable # is defined at the beginning of this file. The surrounding 'W' and 'D' # ensure that the parser in ParseEmptyArg has the correct position, both -# before and after the call to Var_ParsePP. +# before and after the call to Var_Parse. .if empty(W${:UOR}D) . error .endif @@ -146,5 +148,12 @@ ${:U WORD }= variable name with spaces . error .endif +# Parse error: missing closing parenthesis. +.if empty(WORD +. error +.else +. error +.endif + all: @:; |