Makefile ifeq logical or

Question

How do you perform a logical OR using make's ifeq operator?

e.g., I have (simplified):

ifeq ($(GCC_MINOR), 4)
    CFLAGS += -fno-strict-overflow
endif
ifeq ($(GCC_MINOR), 5)
    CFLAGS += -fno-strict-overflow
endif

but would like to consolidate these lines.

(yes, yes, autotools, configure, etc etc; too heavy-handed for the current situation, would like to keep everything within the Makefile here)

[logical opposite of this question: How to Use of Multiple condition in 'ifeq' statement ]

User · Answer

I don t think there s a concise  sensible way to do that  but there are verbose  sensible ways  such as Foo Bah s  and concise  pathological ways  such as  ifneq     findstring   GCC MINOR  4-5       CFLAGS    -fno-strict-overflow endif    which will execute the command provided that the string   GCC MINOR  appears inside the string 4-5

User · Answer

Here more flexible variant  it uses external shell  but allows to check for arbitrary conditions   ifeq    shell test     GCC MINOR      4  -o                           GCC MINOR      5  -o                           TODAY          Friday   amp  amp   printf  true    true      CFLAGS    -fno-strict-overflow endif

User · Answer

ifeq    GCC MINOR   4      CFLAGS    -fno-strict-overflow endif ifeq    GCC MINOR   5      CFLAGS    -fno-strict-overflow endif    Another you can consider using in this case is   GCC42 OR LATER     shell   CXX  -v 2 gt  amp 1     EGREP  -c   gcc version  4  2-9   5-9        -Wstrict-overflow  http   www airs com blog archives 120 ifeq    GCC42 OR LATER  1    CFLAGS    -Wstrict-overflow endif   I actually use the same in my code because I don t want to maintain a separate config or Configure   But you have to use a portable  non-anemic make  like GNU make  gmake   and not Posix s make   And it does not address the issue of logical AND and OR

User · Answer

You can introduce another variable   It doesnt consolidate both checks  but it at least avoids having to put the body in twice   do it    ifeq    GCC MINOR   4      do it   yes endif ifeq    GCC MINOR   5      do it   yes endif ifdef do it     CFLAGS    -fno-strict-overflow endif

User · Answer

As found on the mailing list archive   http   osdir com ml gnu make windows 2004-03 msg00063 html http   osdir com ml gnu make general 2005-10 msg00064 html  one can use the filter function  For example ifeq    GCC MINOR    filter   GCC MINOR  4 5    filter X  A B will return those of A B that are equal to X  Note  while this is not relevant in the above example  this is a XOR operation  I e  if you instead have something like  ifeq  4    filter 4    VAR1    VAR2     And then do e g  make VAR1 4 VAR2 4  the filter will return 4 4  which is not equal to 4  A variation that performs an OR operation instead is  ifneq     filter   GCC MINOR  4 5    where a negative comparison against an empty string is used instead  filter will return en empty string if GCC MINOR doesn t match the arguments   Using the VAR1 VAR2 example it would look like this  ifneq      filter 4    VAR1    VAR2     The downside to those methods is that you have to be sure that these arguments will always be single words  For example  if VAR1 is 4 foo  the filter result is still 4  and the ifneq expression is still true  If VAR1 is 4 5  the filter result is 4 5 and the ifneq expression is true  One easy alternative is to just put the same operation in both the ifeq and else ifeq branch  e g  like this  ifeq    GCC MINOR  4       echo Supported version else ifeq    GCC MINOR  5       echo Supported version else      echo Unsupported version endif

[makefile] Makefile ifeq logical or

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