qt: Fix qmake detection on Linux and Windows

qmake for both Qt4 and Qt5 detection was assuming that it was only used
on Windows, which is incorrect. It can also be used on Linux for
cross-compilation or in general when pkg-config is not available.

It was also not failing properly for both Qt5 and Qt4 when no libraries
were found, and was assuming that the .dll was always available.

Qt4 detection with qmake was also completely broken.

Also prevents unwanted injection of partially-found qt dependencies in
targets by unsetting self.cargs and self.largs

mesonbuild/dependencies.py

@@ -26,7 +26,7 @@ from collections import OrderedDict
 from . mesonlib import MesonException
 from . import mlog
 from . import mesonlib
-from .environment import detect_cpu_family
+from .environment import detect_cpu_family, for_windows
 
 class DependencyException(MesonException):
     def __init__(self, *args, **kwargs):
@@ -821,6 +821,10 @@ class QtBaseDependency(Dependency):
         self.name = name
         self.qtname = name.capitalize()
         self.qtver = name[-1]
+        if self.qtver == "4":
+            self.qtpkgname = 'Qt'
+        else:
+            self.qtpkgname = self.qtname
         self.root = '/usr'
         self.bindir = None
         self.silent = kwargs.get('silent', False)
@@ -838,13 +842,17 @@ class QtBaseDependency(Dependency):
         if len(mods) == 0:
             raise DependencyException('No ' + self.qtname + '  modules specified.')
         type_text = 'cross' if env.is_cross_build() else 'native'
-        found_msg = '{} {} `{{}}` dependency found:'.format(self.qtname, type_text)
-        from_text = 'pkg-config'
+        found_msg = '{} {} {{}} dependency (modules: {}) found:' \
+                    ''.format(self.qtname, type_text, ', '.join(mods))
+        from_text = '`pkg-config`'
         # Prefer pkg-config, then fallback to `qmake -query`
         self._pkgconfig_detect(mods, env, kwargs)
         if not self.is_found:
             from_text = self._qmake_detect(mods, env, kwargs)
             if not self.is_found:
+                # Reset compile args and link args
+                self.cargs = []
+                self.largs = []
                 from_text = '(checked pkg-config, qmake-{}, and qmake)' \
                             ''.format(self.name)
                 self.version = 'none'
@@ -855,6 +863,7 @@ class QtBaseDependency(Dependency):
                 if not self.silent:
                     mlog.log(found_msg.format(from_text), mlog.red('NO'))
                 return
+            from_text = '`{}`'.format(from_text)
         if not self.silent:
             mlog.log(found_msg.format(from_text), mlog.green('YES'))
 
@@ -873,17 +882,14 @@ class QtBaseDependency(Dependency):
         return moc, uic, rcc
 
     def _pkgconfig_detect(self, mods, env, kwargs):
-        if self.qtver == "4":
-            qtpkgname = 'Qt'
-        else:
-            qtpkgname = self.qtname
         modules = OrderedDict()
         for module in mods:
-            modules[module] = PkgConfigDependency(qtpkgname + module, env, kwargs)
+            modules[module] = PkgConfigDependency(self.qtpkgname + module, env, kwargs)
         self.is_found = True
         for m in modules.values():
             if not m.found():
                 self.is_found = False
+                return
             self.cargs += m.get_compile_args()
             self.largs += m.get_link_args()
         self.version = m.modversion
@@ -892,7 +898,7 @@ class QtBaseDependency(Dependency):
             core = modules['Core']
         else:
             corekwargs = {'required': 'false', 'silent': 'true'}
-            core = PkgConfigDependency(qtpkgname + 'Core', env, corekwargs)
+            core = PkgConfigDependency(self.qtpkgname + 'Core', env, corekwargs)
         # Used by self.compilers_detect()
         self.bindir = core.get_pkgconfig_variable('host_bins')
         if not self.bindir:
@@ -947,16 +953,24 @@ class QtBaseDependency(Dependency):
         libdir = qvars['QT_INSTALL_LIBS']
         # Used by self.compilers_detect()
         self.bindir = qvars['QT_INSTALL_BINS']
-        #self.largs.append('-L' + libdir)
+        self.is_found = True
         for module in mods:
             mincdir = os.path.join(incdir, 'Qt' + module)
             self.cargs.append('-I' + mincdir)
-            libfile = os.path.join(libdir, self.qtname + module + '.lib')
-            if not os.path.isfile(libfile):
-                # MinGW links directly to .dll, not to .lib.
-                libfile = os.path.join(self.bindir, self.qtname + module + '.dll')
+            if for_windows(env.is_cross_build(), env):
+                libfile = os.path.join(libdir, self.qtpkgname + module + '.lib')
+                if not os.path.isfile(libfile):
+                    # MinGW can link directly to .dll
+                    libfile = os.path.join(self.bindir, self.qtpkgname + module + '.dll')
+                    if not os.path.isfile(libfile):
+                        self.is_found = False
+                        break
+            else:
+                libfile = os.path.join(libdir, 'lib{}{}.so'.format(self.qtpkgname, module))
+                if not os.path.isfile(libfile):
+                    self.is_found = False
+                    break
             self.largs.append(libfile)
-        self.is_found = True
         return qmake
 
     def _framework_detect(self, qvars, modules, kwargs):