CVS difference for arm/source/04b.mss

Differences between 1.66 and version 1.67
Log of other versions for file arm/source/04b.mss

--- arm/source/04b.mss	2014/07/24 04:20:38	1.66
+++ arm/source/04b.mss	2016/04/23 04:41:13	1.67
@@ -1,9 +1,9 @@
 @Part(04, Root="ada.mss")
-@Comment{$Date: 2014/07/24 04:20:38 $}
+@Comment{$Date: 2016/04/23 04:41:13 $}
 @Comment{$Source: e:\\cvsroot/ARM/Source/04b.mss,v $}
-@Comment{$Revision: 1.66 $}
+@Comment{$Revision: 1.67 $}
 @LabeledClause{Type Conversions}
@@ -2946,11 +2946,15 @@
 @Defn2{Term=[statically matching], Sec=(for subtypes)}
 A subtype @i(statically matches) another subtype of the same type
 if they have statically matching constraints@Chg{Version=[2],New=[,
 @Chg{Version=[3],New=[all predicate specifications that apply to
-them come from the same declarations, ],Old=[]}and, for
+them come from the same declarations, @Chg{Version=[5],New=[Object_Size (see
+@RefSecNum{Operational and Representation Attributes}) has been specified to
+have a nonconfirming value for either both or neither, and the nonconfirming
+values, if any, are the same, ],Old=[]}],Old=[]}and, for
 access subtypes, either both or neither exclude null],Old=[]}.
 Two anonymous access@Chg{Version=[2],New=[-to-object],Old=[]} subtypes
 statically match if their designated subtypes statically
@@ -2970,6 +2974,31 @@
   parameters and access discriminants could never conform, so they couldn't
   be used in separate specifications.]}
+  @ChgRef{Version=[5],Kind=[AddedNormal],ARef=[AI12-0059-1]}
+  @ChgAdded{Version=[5],Text=[If one of the subtypes is not yet frozen, an
+  implementation may have to repeat the check when the subtypes are both
+  frozen (as it is impossible to check the Object_Size part before the subtypes
+  are frozen). This recheck can only make a previously statically matching
+  subtype fail to match; it cannot make a match legal.]}
+  @ChgRef{Version=[5],Kind=[AddedNormal],ARef=[AI12-0059-1]}
+  @ChgAdded{Version=[5],Text=[We exclude the case where both Object_Sizes are
+  confirming so that we don't introduce an incompatibility for
+  existing Ada code. But practically the implementation can simply
+  check that the Object_Size values are the same, as we have a rule in
+  @RefSecNum{Operational and Representation Aspects} that the
+  subtype-specific aspects (such as Object_Size) are always the same for
+  statically matching subtypes. We wrote the rules this way to avoid having
+  wording that appeared to require predicting the future ("would statically
+  match if ...").]}
+  @Comment{We generally do not reference particular paragraphs in the AARM;
+  the paragraph referred to above is paragraph 14. In part, this is because
+  we don't have a way in this tool to link to a particular paragraph,
+  even though a user could add #P14 to the appropriate link and get directly
+  there.}
 @Defn2{Term=[statically matching], Sec=(for ranges)}
 Two ranges of the same type @i{statically match} if both result
@@ -3079,4 +3108,8 @@
   @ChgAdded{Version=[4],Text=[@b<Corrigendum:> Updated wording of
   static compatibility to use the new term "satisfies the predicates"
   (see @RefSecNum{Subtype Predicates}).]}
+  @ChgRef{Version=[5],Kind=[AddedNormal],ARef=[AI12-0059-1]}
+  @ChgAdded{Version=[5],Text=[Updated wording to take nonconfirming values of
+  Object_Size into account.]}

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