build failure due to zlib test in configure #4652

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1. mattdowle commented on Jul 28, 2020

   

   mattdowle

   on Jul 28, 2020

   Last edited by mattdowle

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   Thanks.

   So we're talking about these two lines in configure:

   lib=`pkg-config --libs zlib`
   expr "$lib" : ".*-lz$" >/dev/null
   

   For me, pkg-config --libs zlib contains only -lz on my machine; i.e. it returns -lz only. Could you explain a little more please? Why doesn't that work on FreeBSB? What does pkg-config --libs zlib return for you?
2. wesnm commented on Jul 28, 2020

   

   wesnm

   on Jul 28, 2020

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   There are some differences in the Linux expr and FreeBSD. From the FreeBSD man page:

   Compatibility with previous implementations
   Unless FreeBSD 4.x compatibility is enabled, this version of expr adheres
   to the POSIX Utility Syntax Guidelines, which require that a leading
   argument beginning with a minus sign be considered an option to the
   program. The standard -- syntax may be used to prevent this
   interpretation. However, many historic implementations of expr,

   On my FreeBSD machine:

   [morganw@mercury:~/tmp$]: pkg-config --libs zlib           
   -lz
   [morganw@mercury:~/tmp$]: expr `pkg-config --libs zlib` : '.*-lz$'
   expr: illegal option -- l
   expr: usage: expr [-e] expression
   
   [morganw@mercury:~/tmp$]: expr -- `pkg-config --libs zlib`  : '.*-lz$'
   3
   [morganw@mercury:~/tmp$]: expr x`pkg-config --libs zlib` : '^x.*-lz$'
   4
   

   On a Linux machine:

   [morganw@media:~$]: pkg-config --libs zlib
   -lz
   [morganw@media:~$]: expr `pkg-config --libs zlib` : '.*-lz$'
   3
   [morganw@media:~$]: expr -- `pkg-config --libs zlib` : '.*-lz$'
   3
   [morganw@media:~$]: expr x`pkg-config --libs zlib` : '^x.*-lz$'
   4
   

   The "failure" occurred in 1.12.8 as well, but the end result was a successful build because the src/Makevars file exists in the tree, whereas in 1.13.0 the failure to find zlib causes the configure script to exit before src/Makevars is generated from src/Makevars.in. Perhaps that unconditional exit needs to be reconsidered, given that the OpenMP tests follow it. I don't know how universal the "--" guard for expr is, so perhaps prepending with a string is more portable?

   patch.txt
3. mattdowle commented on Jul 28, 2020

   

   mattdowle

   on Jul 28, 2020

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   Thanks, Morgan! Helps a lot, especially the aspect of not creating Makevars which also occurs in #4640. The Makevars started to be generated in #3984.

   What I had really wanted to do originally was pass the result of pkg-config --libs zlib (i.e. -lz) through to R CMD build somehow. But I didn't know how to do that. So I put the -lz in Makevars (fixed, hardcoded) and added output to configure to tell us if it ever isn't "-lz", or if zlib isn't available, so that users know what to install. But if we're generating Makevars now, then maybe we have a way to pass it through. That would avoid needing to test for "-lz" at all, we could echo the value.

   Thanks again, I think I understand what's going on now.
4. mattdowle

   added this to the 1.13.1 milestone on Jul 28, 2020
5. mattdowle

   closed this as completedin #4662on Aug 4, 2020