Merge branch 'topic/final_package' into 'master'

First implementation for `final_package` check

See merge request eng/libadalang/langkit-query-language!122

Author: raph-amiard

lkql_checker/share/lkql/final_package.lkql

@@ -0,0 +1,40 @@
+fun is_final_pkg(pkg) =
+    |" Whether pkg is a final package; for the moment this means only packages 
+    |" with the `Annotate => (GNATcheck, Final)` aspect, but ultimately this
+    |" will also include packages annotated with the `Final` aspect, as such:
+    |"
+    |" .. code-block:: ada
+    |"     
+    |"     package Pkg with Final is
+    |"     end Pkg;
+    pkg is BasePackageDecl when {
+        val aspect = pkg.p_get_aspect("Annotate");
+        aspect.exists and aspect.value is Aggregate(
+            f_assocs is a@* when a[1] is "GNATcheck" and a[2] is "Final"
+        )
+    }
+
+@check(message="child package cannot have a final parent package",
+       category="Style", subcategory="Programming Practice")
+fun final_package(node) =
+    |" Check that package declarations annotated as final don't have child
+    |" packages
+    |"
+    |" .. note:: We don't do a transitive check, so grandchild packages won't
+    |"    be flagged. We consider this is not necessary, because the child
+    |"    package will be flagged anyway.
+    |"     
+    |" Here is an example:
+    |"
+    |"    .. code-block:: ada
+    |"
+    |"       package Pkg with Annotate => (GNATcheck, Final) is
+    |"       end Pkg;
+    |"        
+    |"       package Pkg.Child is -- FLAGGED
+    |"       end Pkg.Child;
+    |"     
+    |"       package Pkg.Child.Grandchild is -- NOT FLAGGED
+    |"       end Pkg.Child.Grandchild;
+    node is BasePackageDecl(parent is LibraryItem)
+    when is_final_pkg(node.p_semantic_parent())

testsuite/tests/checks/final_package/foo-child-grandchild.ads

@@ -0,0 +1,5 @@
+--  No need to explicitly flag grandchild package, since it cannot exist when
+--  you remove the child one
+
+package Foo.Child.Grandchild is -- NOFLAG
+end Foo.Child.Grandchild;

testsuite/tests/checks/final_package/foo-child.ads

@@ -0,0 +1,2 @@
+package Foo.Child is -- FLAG
+end Foo.Child;

testsuite/tests/checks/final_package/foo.ads

@@ -0,0 +1,2 @@
+package Foo with Annotate => (GNATcheck, Final) is
+end Foo;

testsuite/tests/checks/final_package/test.out

@@ -0,0 +1,4 @@
+foo-child.ads:1:9: rule violation: child package cannot have a final parent package
+1 | package Foo.Child is -- FLAG
+  |         ^^^^^^^^^
+

testsuite/tests/checks/final_package/test.yaml

@@ -0,0 +1,3 @@
+driver: 'checker'
+rule_name: Final_Package
+input_sources: ['foo.ads', 'foo-child.ads', 'foo-child-grandchild.ads']