[Ada] Missing semantic error on ineffective Others_Clause

Message ID 20210506075812.GA125659@adacore.com
State New
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  • [Ada] Missing semantic error on ineffective Others_Clause
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Commit Message

Pierre-Marie de Rodat May 6, 2021, 7:58 a.m.
Compiler fails to reject an Others_Clause in an aggregate for a
constrained array type when previous components of the aggregate cover
the full index range of the array subtype, and the expression in the
Others_Clause has a type incompatible with the component type of the
array. The Others_Clause does not generate any code but the construct is
illegal. The error was previously reported only in -gnatc mode.

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


	* exp_aggr.adb (Expand_Array_Aggregate): If the expression in an
	Others_Clause has not been analyzed because previous analysis of
	the enclosing aggregate showed the clause to be ineffective i.e.
	cover a null range, analyze it now to detect a possible type


diff --git a/gcc/ada/exp_aggr.adb b/gcc/ada/exp_aggr.adb
--- a/gcc/ada/exp_aggr.adb
+++ b/gcc/ada/exp_aggr.adb
@@ -5958,6 +5958,21 @@  package body Exp_Aggr is
             if Nkind (First (Choice_List (Assoc))) = N_Others_Choice then
                Others_Present (Dim) := True;
+               --  An others_clause may be superfluous if previous components
+               --  cover the full given range of a constrained array. In such
+               --  a case an others_clause does not contribute any additional
+               --  components and has not been analyzed. We analyze it now to
+               --  detect type errors in the expression, even though no code
+               --  will be generated for it.
+               if Dim = Aggr_Dimension
+                 and then Nkind (Assoc) /= N_Iterated_Component_Association
+                 and then not Analyzed (Expression (Assoc))
+                 and then not Box_Present (Assoc)
+               then
+                  Preanalyze_And_Resolve (Expression (Assoc), Ctyp);
+               end if;
             end if;
          end if;