Merge branch 'topic/524' into 'master'

Add detector for KP-19997

Closes #524

See merge request eng/libadalang/langkit-query-language!531

Author: thvnx

lkql_checker/share/lkql/kp/KP-19997.lkql

@@ -0,0 +1,26 @@
+# Flag calls to Unchecked_Conversion where arguments have different
+# Scalar_Storage_Order.
+
+import stdlib
+
+fun sso(decl) =
+    |" Return the ``Scalar_Storage_Order`` associated to ``decl`` in the form
+    |" of a fully qualified name.
+    {
+        val aspect = decl.p_get_aspect("Scalar_Storage_Order");
+
+        (match aspect.value
+           | i@Identifier => i
+           | * => stdlib.default_bit_order()
+        ).p_referenced_decl().p_canonical_fully_qualified_name()
+    }
+
+@check(help="possible occurrence of KP 19997",
+       message="possible occurrence of KP 19997 if compiled with optimization")
+fun kp_19997(node) =
+    node is gsi@GenericSubpInstantiation
+    when gsi.f_kind is SubpKindFunction
+    and gsi.p_designated_generic_decl().p_get_uninstantiated_node()
+        .p_canonical_fully_qualified_name() == "ada.unchecked_conversion"
+    and (sso(gsi.f_params[1].f_r_expr.p_referenced_decl()) !=
+         sso(gsi.f_params[2].f_r_expr.p_referenced_decl()))

testsuite/tests/checks/KP-19997/prj.gpr

@@ -0,0 +1,2 @@
+project Prj is
+end Prj;

testsuite/tests/checks/KP-19997/test.adb

@@ -0,0 +1,23 @@
+with Ada.Unchecked_Conversion;
+
+with Interfaces;  use Interfaces;
+with System;      use System;
+
+procedure Test is
+   type Bytes is array (0 .. 3) of Unsigned_8
+     with Scalar_Storage_Order => Low_Order_First;
+
+   type Bytes_BE is new Bytes
+     with Scalar_Storage_Order => High_Order_First;
+
+   type Bytes_LE is new Bytes
+     with Scalar_Storage_Order => Low_Order_First;
+
+   function To_Bytes is new Ada.Unchecked_Conversion (Unsigned_32, Bytes);  -- NOFLAG
+
+   function To_Bytes_BE is new Ada.Unchecked_Conversion (Unsigned_32, Bytes_BE);  --  FLAG
+
+   function To_Bytes_LE is new Ada.Unchecked_Conversion (Unsigned_32, Bytes_LE);  --  NOFLAG
+begin
+   null;
+end;

testsuite/tests/checks/KP-19997/test.out

@@ -0,0 +1,4 @@
+test.adb:18:13: rule violation: possible occurrence of KP 19997 if compiled with optimization
+18 |    function To_Bytes_BE is new Ada.Unchecked_Conversion (Unsigned_32, Bytes_BE);  --  FLAG
+   |             ^^^^^^^^^^^
+

testsuite/tests/checks/KP-19997/test.yaml

@@ -0,0 +1,3 @@
+driver: 'checker'
+rule_name: KP_19997
+project: 'prj.gpr'

testsuite/tests/gnatcheck/xml_help/test.out

@@ -95,6 +95,7 @@ testsuite_driver: No output file generated by gnatcheck
       <check switch="+Rkp_19853" label="possible occurrence of KP 19853"/>
       <check switch="+Rkp_19901" label="possible occurrence of KP 19901"/>
       <check switch="+Rkp_19915" label="occurrence of KP 19915"/>
+      <check switch="+Rkp_19997" label="possible occurrence of KP 19997"/>
       <check switch="+Rkp_20023" label="occurrence of KP 20023"/>
       <check switch="+Rkp_ob03_009" label="possible occurrence of KP OB03-009"/>
       <check switch="+Rkp_p226_024" label="possible occurrence of KP P226-024 - global analysis required"/>
@@ -616,6 +617,7 @@ testsuite_driver: No output file generated by gnatcheck
       <check switch="+Rkp_19853" label="possible occurrence of KP 19853"/>
       <check switch="+Rkp_19901" label="possible occurrence of KP 19901"/>
       <check switch="+Rkp_19915" label="occurrence of KP 19915"/>
+      <check switch="+Rkp_19997" label="possible occurrence of KP 19997"/>
       <check switch="+Rkp_20023" label="occurrence of KP 20023"/>
       <check switch="+Rkp_ob03_009" label="possible occurrence of KP OB03-009"/>
       <check switch="+Rkp_p226_024" label="possible occurrence of KP P226-024 - global analysis required"/>