Add audit check about troublesome libraries (#611)

Author: giordano

src/Auditor.jl

@@ -290,6 +290,9 @@ function check_dynamic_linkage(oh, prefix, bin_files;
                     else
                         if !silent
                             @warn("Linked library $(libname) could not be resolved and could not be auto-mapped")
+                            if is_troublesome_library_link(libname, platform)
+                                @warn("Depending on $(libname) is known to cause problems at runtime, make sure to link against the JLL library instead")
+                            end
                         end
                         all_ok = false
                     end

src/auditor/dynamic_linkage.jl

@@ -400,3 +400,20 @@ function update_linkage(prefix::Prefix, platform::Platform, path::AbstractString
 
     return new_libpath
 end
+
+
+"""
+    is_troublesome_library_link(libname::AbstractString, platform::Platform)
+
+Return `true` if depending on `libname` is known to cause problems at runtime, `false` otherwise.
+"""
+is_troublesome_library_link(libname::AbstractString, platform::Platform) = false
+
+# In https://github.com/JuliaGtk/GtkSourceWidget.jl/pull/9 we found that
+# depending on this libraries is an indication that system copies of libxml and
+# libiconv has been picked up during compilation.  At runtime, the system copies
+# will be loaded, which are very likely to be incompatible with those provided
+# by JLL packages.  The solution is to make sure that JLL copies of these
+# libraries are used.
+is_troublesome_library_link(libname::AbstractString, ::MacOS) =
+    libname in ("/usr/lib/libxml2.2.dylib", "/usr/lib/libiconv.2.dylib")