[Ada] Dangling cursor checks in Element function

In Ada.Containers.Ordered_Maps, if a dangling cursor is passed to the Element
function, execution is erroneous. Therefore, the compiler is not obligated to
detect this error. However, this patch inserts code that will detect this error
in some cases, and raise Program_Error. The same applies to Ordered_Sets,
Ordered_Multisets, Indefinite_Ordered_Maps, Indefinite_Ordered_Sets, and
Indefinite_Ordered_Multisets. No test available for erroneous execution.

2018-06-11  Bob Duff  <duff@adacore.com>

gcc/ada/

	* libgnat/a-ciorma.adb, libgnat/a-ciormu.adb, libgnat/a-ciorse.adb,
	libgnat/a-coorma.adb, libgnat/a-coormu.adb, libgnat/a-coorse.adb:
	(Element): Add code to detect dangling cursors in some cases.

From-SVN: r261424

7 files changed, 48 insertions, 0 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 84dd18b..e032be3 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,9 @@
+2018-06-11  Bob Duff  <duff@adacore.com>
+
+	* libgnat/a-ciorma.adb, libgnat/a-ciormu.adb, libgnat/a-ciorse.adb,
+	libgnat/a-coorma.adb, libgnat/a-coormu.adb, libgnat/a-coorse.adb:
+	(Element): Add code to detect dangling cursors in some cases.
+
 2018-06-11  Yannick Moy  <moy@adacore.com>
 
 	* sem_ch6.adb (Build_Subprogram_Declaration): Mark parameters as coming
diff --git a/gcc/ada/libgnat/a-ciorma.adb b/gcc/ada/libgnat/a-ciorma.adb
index a981f72..000851a 100644
--- a/gcc/ada/libgnat/a-ciorma.adb
+++ b/gcc/ada/libgnat/a-ciorma.adb
@@ -541,6 +541,13 @@ package body Ada.Containers.Indefinite_Ordered_Maps is
            "Position cursor of function Element is bad";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "Position cursor of function Element is bad");
 
diff --git a/gcc/ada/libgnat/a-ciormu.adb b/gcc/ada/libgnat/a-ciormu.adb
index 2420788..5c3e9f7 100644
--- a/gcc/ada/libgnat/a-ciormu.adb
+++ b/gcc/ada/libgnat/a-ciormu.adb
@@ -545,6 +545,13 @@ package body Ada.Containers.Indefinite_Ordered_Multisets is
          raise Program_Error with "Position cursor is bad";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "bad cursor in Element");
 
diff --git a/gcc/ada/libgnat/a-ciorse.adb b/gcc/ada/libgnat/a-ciorse.adb
index e656513..7394a4a 100644
--- a/gcc/ada/libgnat/a-ciorse.adb
+++ b/gcc/ada/libgnat/a-ciorse.adb
@@ -534,6 +534,13 @@ package body Ada.Containers.Indefinite_Ordered_Sets is
          raise Program_Error with "Position cursor is bad";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "bad cursor in Element");
 
diff --git a/gcc/ada/libgnat/a-coorma.adb b/gcc/ada/libgnat/a-coorma.adb
index 05eea5b..5fd3ec6 100644
--- a/gcc/ada/libgnat/a-coorma.adb
+++ b/gcc/ada/libgnat/a-coorma.adb
@@ -481,6 +481,13 @@ package body Ada.Containers.Ordered_Maps is
            "Position cursor of function Element equals No_Element";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "Position cursor of function Element is bad");
 
diff --git a/gcc/ada/libgnat/a-coormu.adb b/gcc/ada/libgnat/a-coormu.adb
index 0fc1063..c114cf9 100644
--- a/gcc/ada/libgnat/a-coormu.adb
+++ b/gcc/ada/libgnat/a-coormu.adb
@@ -502,6 +502,13 @@ package body Ada.Containers.Ordered_Multisets is
          raise Constraint_Error with "Position cursor equals No_Element";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "bad cursor in Element");
 
diff --git a/gcc/ada/libgnat/a-coorse.adb b/gcc/ada/libgnat/a-coorse.adb
index 606938e..1f96d39 100644
--- a/gcc/ada/libgnat/a-coorse.adb
+++ b/gcc/ada/libgnat/a-coorse.adb
@@ -480,6 +480,13 @@ package body Ada.Containers.Ordered_Sets is
          raise Constraint_Error with "Position cursor equals No_Element";
       end if;
 
+      if Checks and then
+        (Left (Position.Node) = Position.Node
+           or else Right (Position.Node) = Position.Node)
+      then
+         raise Program_Error with "dangling cursor";
+      end if;
+
       pragma Assert (Vet (Position.Container.Tree, Position.Node),
                      "bad cursor in Element");