pkgconfig: Warn if library has name_prefix/suffix set

GCC/Clang won't be able to find it via an -lfoo flag, so the pkg-config
file might be unusable.

Fixes https://github.com/mesonbuild/meson/issues/889

mesonbuild/build.py

@@ -229,6 +229,8 @@ class BuildTarget():
         self.include_dirs = []
         self.link_targets = []
         self.link_depends = []
+        self.name_prefix_set = False
+        self.name_suffix_set = False
         self.filename = 'no_name'
         # The file with debugging symbols
         self.debug_filename = None
@@ -514,6 +516,7 @@ class BuildTarget():
             elif not isinstance(name_prefix, str):
                 raise InvalidArguments('name_prefix must be a string.')
             self.prefix = name_prefix
+            self.name_prefix_set = True
         if 'name_suffix' in kwargs:
             name_suffix = kwargs['name_suffix']
             if isinstance(name_suffix, list):
@@ -523,6 +526,7 @@ class BuildTarget():
                 if not isinstance(name_suffix, str):
                     raise InvalidArguments('name_suffix must be a string.')
                 self.suffix = name_suffix
+                self.name_suffix_set = True
         if isinstance(self, StaticLibrary):
             # You can't disable PIC on OS X. The compiler ignores -fno-PIC.
             # PIC is always on for Windows (all code is position-independent

mesonbuild/modules/pkgconfig.py

@@ -14,15 +14,16 @@
 
 from .. import coredata, build
 from .. import mesonlib
+from .. import mlog
 import os
 
 class PkgConfigModule:
 
-    def generate_pkgconfig_file(self, state, libraries, subdirs, name, description, version, filebase,
+    def generate_pkgconfig_file(self, state, libraries, subdirs, name, description, version, pcfile,
                                 pub_reqs, priv_reqs, priv_libs):
         coredata = state.environment.get_coredata()
         outdir = state.environment.scratch_dir
-        fname = os.path.join(outdir, filebase + '.pc')
+        fname = os.path.join(outdir, pcfile)
         with open(fname, 'w') as ofile:
             ofile.write('prefix=%s\n' % coredata.get_builtin_option('prefix'))
             ofile.write('libdir=${prefix}/%s\n' %
@@ -43,9 +44,16 @@ class PkgConfigModule:
                 ofile.write(
                     'Libraries.private: {}\n'.format(' '.join(priv_libs)))
             ofile.write('Libs: -L${libdir} ')
+            msg = 'Library target {0!r} has {1!r} set. Compilers ' \
+                  'may not find it from its \'-l{0}\' linker flag in the ' \
+                  '{2!r} pkg-config file.'
             for l in libraries:
                 if l.custom_install_dir:
                     ofile.write('-L${prefix}/%s ' % l.custom_install_dir)
+                if l.name_prefix_set:
+                    mlog.log(mlog.red('WARNING:'), msg.format(l.name, 'name_prefix', pcfile))
+                if l.name_suffix_set:
+                    mlog.log(mlog.red('WARNING:'), msg.format(l.name, 'name_suffix', pcfile))
                 ofile.write('-l%s ' % l.name)
             ofile.write('\n')
             ofile.write('CFlags: ')
@@ -92,7 +100,7 @@ class PkgConfigModule:
             pkgroot = os.path.join(state.environment.coredata.get_builtin_option('libdir'), 'pkgconfig')
         if not isinstance(pkgroot, str):
             raise mesonlib.MesonException('Install_dir must be a string.')
-        self.generate_pkgconfig_file(state, libs, subdirs, name, description, version, filebase,
+        self.generate_pkgconfig_file(state, libs, subdirs, name, description, version, pcfile,
                                      pub_reqs, priv_reqs, priv_libs)
         return build.Data(False, state.environment.get_scratch_dir(), [pcfile], pkgroot)