./curlopt-constants.c:19:58: error: non-void function 'constant' should return a value [-Wreturn-type]

[l29ah]

4.17:

clang -c -I/usr/include -D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2 -O2 -pipe -O2 -pipe -march=native -DVERSION="4.17" -DXS_VERSION="4.17" -fPIC "-I/usr/lib64/perl5/5.24.0/x86_64-linux-thread-multi/CORE" Curl.c
In file included from Curl.xs:574:
./curlopt-constants.c:19:58: error: non-void function 'constant' should return a value [-Wreturn-type]
if (strEQ(name, "DID_MEMORY_FUNC_TYPEDEFS")) return CURL_DID_MEMORY_FUNC_TYPEDEFS;
^

[spagu]

Problem is here https://github.com/szbalint/WWW--Curl/blob/master/Makefile.PL

it is parsing all defines from https://github.com/curl/curl/blob/master/include/curl/curl.h
last change was done here : curl/curl@a9a1d30
and make parsing fails as define has no value which is correct for curl.h

did talk to curl in here curl/curl#839

orginal code for Makefile.PL on line 140 (sub parse_constants)
if ($e =~ /(OBSOLETE|^CURL_EXTERN|_LAST\z|_LASTENTRY\z)/) {

Updated code that works for me:
if ($e =~ /(OBSOLETE|^CURL_EXTERN|_LAST\z|_LASTENTRY\z|CURL_DID_MEMORY_FUNC_TYPEDEFS\z)/) {

but maybe there is better way to fix that

[sparvu]

same here also on FreeBSD 10.3:

cc -c  -I/opt/kronometrix/include  -DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_FORTIFY_SOURCE=2 -O3    -DVERSION=\"4.17\"  -DXS_VERSION=\"4.17\" -DPIC -fPIC "-I/opt/kronometrix/perl/lib/5.24.0/amd64-freebsd/CORE"   Curl.c
In file included from Curl.xs:574:
./curlopt-constants.c:19:58: error: non-void function 'constant' should return a value [-Wreturn-type]
            if (strEQ(name, "DID_MEMORY_FUNC_TYPEDEFS")) return CURL_DID_MEMORY_FUNC_TYPEDEFS;
                                                         ^
./curlopt-constants.c:2047:44: warning: implicit conversion from 'unsigned long' to 'int' changes value from
      18446744073709551599 to -17 [-Wconstant-conversion]
            if (strEQ(name, "ANY")) return CURLAUTH_ANY;
                                    ~~~~~~ ^~~~~~~~~~~~
/opt/kronometrix/include/curl/curl.h:668:32: note: expanded from macro 'CURLAUTH_ANY'
#define CURLAUTH_ANY          (~CURLAUTH_DIGEST_IE)
                               ^~~~~~~~~~~~~~~~~~~
In file included from Curl.xs:574:
./curlopt-constants.c:2048:48: warning: implicit conversion from 'unsigned long' to 'int' changes value from
      18446744073709551598 to -18 [-Wconstant-conversion]
            if (strEQ(name, "ANYSAFE")) return CURLAUTH_ANYSAFE;
                                        ~~~~~~ ^~~~~~~~~~~~~~~~
/opt/kronometrix/include/curl/curl.h:669:32: note: expanded from macro 'CURLAUTH_ANYSAFE'
#define CURLAUTH_ANYSAFE      (~(CURLAUTH_BASIC|CURLAUTH_DIGEST_IE))
                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Curl.xs:1100:26: warning: implicit conversion from enumeration type 'CURLINFO' to different enumeration type
      'CURLoption' [-Wenum-conversion]
                curl_easy_setopt(easy, CURLINFO_PRIVATE, NULL);
                ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/opt/kronometrix/include/curl/curl.h:2432:68: note: expanded from macro 'curl_easy_setopt'
#define curl_easy_setopt(handle,opt,param) curl_easy_setopt(handle,opt,param)
                                                                   ^
3 warnings and 1 error generated.
*** Error code 1

[plijnzaad]

I also run into difficulties with
Cannot find curl.h - cannot build constants files - see Makefile.PL
On my Mac OSX 10.14.6 I don't have admin rights so I can not easily update curl and/or curl-dev (currently curl 7.54.0 (x86_64-apple-darwin18.0) libcurl/7.54.0 LibreSSL/2.6.5 zlib/1.2.11 nghttp2/1.24.1 )

I therefore use brew curl ( curl 7.67.0 (x86_64-apple-darwin18.7.0) libcurl/7.67.0 SecureTransport zlib/1.2.11, Release-Date: 2019-11-06)

Regarding @spagu 's comment ( #16 (comment)), I had to extend the regexp a bit more (at least for the www-Curl-4.17 release):

if($e =~ /(OBSOLETE|^CURL_EXTERN|^CURL_STRICTER\z|_LAST\z|_LASTENTRY\z|CURL_DID_MEMORY_FUNC_TYPEDEFS\z|CURLINC_CURL_H\z)/)
(this is for the Apple LLVM version 10.0.1 (clang-1001.0.46.4) compiler and the brew version of curl)

There is an additional problem with the clang C-preprocessor which can be solved by replacing cpp with cc -E in Makefile.PL (around line 100)

Lastly, there is a problem in the Curl.xs file which contains a struct void * curlm in the definition of struct perl_curl_multi; I believe this should simply be void * curlm;

I don't have a full git clone of the latest so I just provide patches against the he www-Curl-4.17 versions:

Makefile.PL:

*** Makefile.PL.orig	Fri Feb 21 17:08:09 2014
--- Makefile.PL	Tue Nov 26 10:52:09 2019
***************
*** 100,106 ****
       print "Found curl.h in $curl_h\n";
       my @syms;
       my $has_cpp = 0;
!      open(H_IN, "-|", "cpp", $curl_h) and $has_cpp++;
       unless ($has_cpp) {
           warn "No working cpp ($!).  Parsing curl.h in Perl";
           open(H_IN, "<", $curl_h) or die("Can't open curl.h at path $curl_h, because: ".$!);
--- 100,108 ----
       print "Found curl.h in $curl_h\n";
       my @syms;
       my $has_cpp = 0;
! #     open(H_IN, "-|", "cpp", $curl_h) and $has_cpp++;
!      open(H_IN, "-|", "cc -E", $curl_h) and $has_cpp++;
! ## bug in Mac clang, see https://stackoverflow.com/questions/42031921/unterminated-unconditional-directive-error-when-preprocessing-c-code
       unless ($has_cpp) {
           warn "No working cpp ($!).  Parsing curl.h in Perl";
           open(H_IN, "<", $curl_h) or die("Can't open curl.h at path $curl_h, because: ".$!);
***************
*** 127,133 ****
      close H;
  
      for my $e (sort @syms) {
!        if($e =~ /(OBSOLETE|^CURL_EXTERN|_LAST\z|_LASTENTRY\z)/) {
            next;
         }
         my ($group) = $e =~ m/^([^_]+_)/;
--- 129,136 ----
      close H;
  
      for my $e (sort @syms) {
! #       if($e =~ /(OBSOLETE|^CURL_EXTERN|_LAST\z|_LASTENTRY\z)/) {
! 	if($e =~ /(OBSOLETE|^CURL_EXTERN|^CURL_STRICTER\z|_LAST\z|_LASTENTRY\z|CURL_DID_MEMORY_FUNC_TYPEDEFS\z|CURLINC_CURL_H\z)/) {
            next;
         }
         my ($group) = $e =~ m/^([^_]+_)/;

---

Curl.xs:

*** Curl.xs.orig	Fri Feb 21 17:08:30 2014
--- Curl.xs	Tue Nov 26 10:48:06 2019
***************
*** 73,79 ****
  #ifdef __CURL_MULTI_H
      struct CURLM *curlm;
  #else
!     struct void *curlm;
  #endif
  } perl_curl_multi;
  
--- 73,80 ----
  #ifdef __CURL_MULTI_H
      struct CURLM *curlm;
  #else
!   /*    struct void *curlm; */
!     void *curlm;
  #endif
  } perl_curl_multi;
  

[plijnzaad]

Just for completeness, a reply by the maintainer is on https://rt.cpan.org/Public/Bug/Display.html?id=131089