[COMMITTED 23/30] ada: Fix internal error on loop parameter specifications

[Marc Poulhiès]

From: Piotr Trojanek <troja...@adacore.com>

Originally loop parameter specification only occurred in loops, but now
it also occurs in quantified expressions. This patch guards against
flagging non-loop nodes as null loop statements. This was causing
internal compiler errors that were only visible with switch -gnatdk,
which happens to be default in GNATprove testsuite.

gcc/ada/ChangeLog:

        * sem_ch5.adb (Analyze_Loop_Parameter_Specification): Only set
        flag Is_Null_Loop when loop parameter specification comes from
        a loop and not from a quantified expression.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_ch5.adb | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/gcc/ada/sem_ch5.adb b/gcc/ada/sem_ch5.adb
index 131195a78c7..4c82e274ddb 100644
--- a/gcc/ada/sem_ch5.adb
+++ b/gcc/ada/sem_ch5.adb
@@ -3303,7 +3303,10 @@ package body Sem_Ch5 is
                   --  set the appropriate flag to remove the loop entirely
                   --  during expansion.
 
-                  Set_Is_Null_Loop (Loop_Nod);
+                  if Nkind (Loop_Nod) = N_Loop_Statement then
+                     Set_Is_Null_Loop (Loop_Nod);
+                  end if;
+
                   Null_Range := True;
                end if;
 
@@ -3339,7 +3342,9 @@ package body Sem_Ch5 is
                --  since it is likely that these warnings will be inappropriate
                --  if the loop never actually executes, which is likely.
 
-               Set_Suppress_Loop_Warnings (Loop_Nod);
+               if Nkind (Loop_Nod) = N_Loop_Statement then
+                  Set_Suppress_Loop_Warnings (Loop_Nod);
+               end if;
 
                --  The other case for a warning is a reverse loop where the
                --  upper bound is the integer literal zero or one, and the
@@ -3441,12 +3446,13 @@ package body Sem_Ch5 is
                           Subtype_Mark (DS));
                      end if;
 
-                     Set_Is_Null_Loop (Loop_Nod);
-                     Null_Range := True;
+                     if Nkind (Loop_Nod) = N_Loop_Statement then
+                        Set_Is_Null_Loop (Loop_Nod);
 
-                     --  Suppress other warnings about the body of the loop, as
-                     --  it will never execute.
-                     Set_Suppress_Loop_Warnings (Loop_Nod);
+                        --  Suppress other warnings about the body of the loop,
+                        --  as it will never execute.
+                        Set_Suppress_Loop_Warnings (Loop_Nod);
+                     end if;
                   end if;
                end;
             end if;
-- 
2.43.0