[Ada] Remove new strict-alignment check added by AI12-0001

2019-12-16  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* freeze.adb (Check_Strict_Alignment): Remove new check on
	Has_Aliased_Components for array types.

From-SVN: r279433

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 5533c1cca533e2ea47a6fe95193db3bd1733ac1d..8f5c089bf87a85c948d6a6eb9d3fbd76822fcd93 100644 (file)
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-16  Eric Botcazou  <ebotcazou@adacore.com>
+
+       * freeze.adb (Check_Strict_Alignment): Remove new check on
+       Has_Aliased_Components for array types.
+
 2019-12-16  Ed Schonberg  <schonberg@adacore.com>
 
        * sem_ch4.adb (Try_Container_Indexing): In the case of a derived

diff --git a/gcc/ada/freeze.adb b/gcc/ada/freeze.adb
index 36cf63cad165d9e2c8815c9c1f862aa8c821edce..0312ca704aa78704233dd53fcfb28f60bf236653 100644 (file)
--- a/gcc/ada/freeze.adb
+++ b/gcc/ada/freeze.adb
@@ -1614,24 +1614,22 @@ package body Freeze is
          Set_Strict_Alignment (E);
 
       elsif Is_Array_Type (E) then
-         if Has_Aliased_Components (E)
-           or else Strict_Alignment (Component_Type (E))
-         then
-            Set_Strict_Alignment (E);
-         end if;
+         Set_Strict_Alignment (E, Strict_Alignment (Component_Type (E)));
 
-      elsif Is_Record_Type (E) then
-         --  ??? If the type has convention C_Pass_By_Copy, we consider
-         --  that it may be packed even if it contains aliased parts.
-         --  Such types are very unlikely to be misaligned in practice
-         --  and this makes the compiler accept dubious representation
-         --  clauses used in Florist on types containing arrays with
-         --  aliased components.
-
-         if C_Pass_By_Copy (E) then
-            return;
-         end if;
+         --  ??? AI12-001: Any component of a packed type that contains an
+         --  aliased part must be aligned according to the alignment of its
+         --  subtype (RM 13.2(7)). This means that the following test:
+
+         --    if Has_Aliased_Components (E) then
+         --      Set_Strict_Alignment (E);
+         --    end if;
 
+         --  should be implemented here. Unfortunately it would break Florist,
+         --  which has the bad habit of overaligning all the types it declares
+         --  on 32-bit platforms. Other legacy codebases could also be affected
+         --  because this check has historically been missing in GNAT.
+
+      elsif Is_Record_Type (E) then
          Comp := First_Component (E);
          while Present (Comp) loop
             if not Is_Type (Comp)