pkgconfig: Fix linking to a custom target

When generating pkgconfig file for a library that links to an
uninstalled static library built by custom_target() Meson was crashing
when trying to access some attributes that does not exist on that class.

Also fix is_internal() implementation, it only really make sense on a
CustomTargetIndex or if CustomTarget has only a single output.

2 files changed, 13 insertions, 9 deletions

diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 7c873b2..70f52f9 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -2588,13 +2588,12 @@ class CustomTarget(Target, CommandBase):
         return []
 
     def is_internal(self) -> bool:
-        if not self.should_install():
-            return True
-        for out in self.get_outputs():
-            # Can't check if this is a static library, so try to guess
-            if not out.endswith(('.a', '.lib')):
-                return False
-        return True
+        '''
+        Returns True iif this is a not installed static library.
+        '''
+        if len(self.outputs) != 1:
+            return False
+        return CustomTargetIndex(self, self.outputs[0]).is_internal()
 
     def extract_all_objects_recurse(self) -> T.List[T.Union[str, 'ExtractedObjects']]:
         return self.get_outputs()
@@ -2764,7 +2763,11 @@ class CustomTargetIndex(HoldableObject):
         return self.target.should_install()
 
     def is_internal(self) -> bool:
-        return self.target.is_internal()
+        '''
+        Returns True iif this is a not installed static library
+        '''
+        suf = os.path.splitext(self.output)[-1]
+        return suf in {'.a', '.lib'} and not self.should_install()
 
     def extract_all_objects_recurse(self) -> T.List[T.Union[str, 'ExtractedObjects']]:
         return self.target.extract_all_objects_recurse()
diff --git a/mesonbuild/modules/pkgconfig.py b/mesonbuild/modules/pkgconfig.py
index 4a0b39e..6c5d347 100644
--- a/mesonbuild/modules/pkgconfig.py
+++ b/mesonbuild/modules/pkgconfig.py
@@ -183,7 +183,8 @@ class DependenciesHelper:
         # lists in case a library is link_with and link_whole at the same time.
         # See remove_dups() below.
         self.link_whole_targets.append(t)
-        self._add_lib_dependencies(t.link_targets, t.link_whole_targets, t.external_deps, public)
+        if isinstance(t, build.BuildTarget):
+            self._add_lib_dependencies(t.link_targets, t.link_whole_targets, t.external_deps, public)
 
     def add_version_reqs(self, name, version_reqs):
         if version_reqs: