[Ada] Sinfo: refine comment for Do_Range_Check

2019-07-09  Yannick Moy  <moy@adacore.com>

gcc/ada/

	* sinfo.ads: Refine comment for Do_Range_Check.

From-SVN: r273277

gcc/ada/ChangeLog

 2019-07-09  Yannick Moy  <moy@adacore.com>
 
+	* sinfo.ads: Refine comment for Do_Range_Check.
+
+2019-07-09  Yannick Moy  <moy@adacore.com>
+
 	* exp_spark.adb (Expand_SPARK_N_Attribute_Reference): Expand
 	attribute reference on Enum_Rep.
 

gcc/ada/sinfo.ads

@@ -754,7 +754,11 @@ package Sinfo is
    --  GNATprove mode. As a special case, the front end does not insert a
    --  Do_Division_Check flag on float exponentiation expressions, for the case
    --  where the value is 0.0 and the exponent is negative, although this case
-   --  does lead to a division check failure.
+   --  does lead to a division check failure. As another special case,
+   --  the frontend does not insert a Do_Range_Check on an allocator where
+   --  the designated type is scalar, and the designated type is more
+   --  constrained than the type of the initialized allocator value or the type
+   --  of the default value for an uninitialized allocator.
 
    --  Note: the expander always takes care of the Do_Range check case,
    --  so this flag will never be set in the expanded tree passed to the