[Ada] Spurious size error on fixed point type with aspect Small

[Pierre-Marie de Rodat <derodat at adacore dot com>]

This path fixes a spurious size error on a fixed point that carries an
aspect specification for the 'Small of the type, when there is a subsequent
derivation of that type before the type is frozen, the given 'Small is not
not a power of two, and the bounds of the type require its full size, also
given by an aspect specification.

Tested on x86_64-pc-linux-gnu, committed on trunk

2018-05-22  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* freeze.adb (Freeze_Fixed_Point_Type): If the first subtype has
	delayed aspects, analyze them now, os that the representation of the
	type (size, bounds) can be computed and validated.

gcc/testsuite/

	* gnat.dg/fixedpnt3.adb: New testcase.

--- gcc/ada/freeze.adb
+++ gcc/ada/freeze.adb
@@ -7466,6 +7466,16 @@ package body Freeze is
    --  Start of processing for Freeze_Fixed_Point_Type
 
    begin
+      --  The type, or its first subtype if we are freezing the anonymous
+      --  base, may have a delayed Small aspect. It must be analyzed now,
+      --  so that all characteristics of the type (size, bounds) can be
+      --  computed and validated in the call to Minimum_Size that follows.
+
+      if Has_Delayed_Aspects (First_Subtype (Typ)) then
+         Analyze_Aspects_At_Freeze_Point (First_Subtype (Typ));
+         Set_Has_Delayed_Aspects (First_Subtype (Typ), False);
+      end if;
+
       --  If Esize of a subtype has not previously been set, set it now
 
       if Unknown_Esize (Typ) then

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/fixedpnt3.adb
@@ -0,0 +1,16 @@
+--  { dg-do compile }
+--  { dg-options "-gnatws" }
+
+procedure Fixedpnt3 is
+  C_Unit : constant := 0.001;
+
+  type T_Fixed_Point is
+     delta C_Unit range (-2 ** 63) * C_Unit .. (2 ** 63 - 1) * C_Unit
+     with Size  => 64, Small => C_Unit;
+
+  type T_Short_Fixed_Point is
+     new T_Fixed_Point range (-2 ** 31) * C_Unit .. (2 ** 31 - 1) * C_Unit
+     with Size  => 32;
+begin
+   null;
+end Fixedpnt3;