dar @2.6.13_0 fails to build on macOS 11 (Big Sur) "ld: symbol(s) not found for architecture x86_64"

[jgosmann (Jan Gosmann)]

The command sudo port install dar fails with the following output:

--->  Computing dependencies for dar
--->  Fetching archive for dar
--->  Attempting to fetch dar-2.6.13_0.darwin_20.x86_64.tbz2 from https://packages.macports.org/dar
--->  Attempting to fetch dar-2.6.13_0.darwin_20.x86_64.tbz2 from https://lil.fr.packages.macports.org/dar
--->  Attempting to fetch dar-2.6.13_0.darwin_20.x86_64.tbz2 from https://mse.uk.packages.macports.org/dar
--->  Fetching distfiles for dar
--->  Verifying checksums for dar
--->  Extracting dar
--->  Configuring dar
--->  Building dar
Error: Failed to build dar: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_archivers_dar/dar/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port dar failed

A snippet of the error output from the log (full log attached):

:info:build libtool: link: /usr/bin/clang++ -dynamiclib  -o .libs/libdar64.6000.dylib [...]
:info:build Undefined symbols for architecture x86_64:
:info:build   "_curl_easy_cleanup", referenced from:
:info:build       libdar::mycurl_easyhandle_node::~mycurl_easyhandle_node() in mycurl_easyhandle_sharing.o
:info:build       libdar::mycurl_easyhandle_node::~mycurl_easyhandle_node() in mycurl_shared_handle.o
:info:build   "_curl_easy_duphandle", referenced from:
:info:build       libdar::mycurl_easyhandle_node::mycurl_easyhandle_node(libdar::mycurl_easyhandle_node const&) in mycurl_easyhandle_node.o
...

[ryandesign (Ryan Carsten Schmidt)]

The well-known libtool macOS 11+ undefined symbol bug.

[ryandesign (Ryan Carsten Schmidt)]

In 7b48f5be3ebf72df8ed4b07971d4ffd92503dbd6/macports-ports (master):

dar: Fix libtool macOS 11+ bug

Closes: #61971