[2/2] Specially handle array contexts in Ada expression resolution

Message ID 20210122211023.997478-3-tromey@adacore.com
State New
Headers show
Series
  • Add another case to Ada expression resolution
Related show

Commit Message

Tom Tromey Jan. 22, 2021, 9:10 p.m.
A user noticed that the Ada expression code in gdb did not
automatically disambiguate an enumerator in an array context.  That
is, an expression like "print array(enumerator)" is not ambiguous,
even if "enumerator" is declared in multiple enumerations, because the
correct one can be found by examining the array's index type.

This patch changes the Ada expression resolution code to handle this
case.

gdb/ChangeLog
2021-01-22  Tom Tromey  <tromey@adacore.com>

	* ada-lang.c (resolve_subexp): Handle array context.

gdb/testsuite/ChangeLog
2021-01-22  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/local-enum.exp: Add enumerator resolution test.
---
 gdb/ChangeLog                        |  4 ++++
 gdb/ada-lang.c                       | 22 +++++++++++++++++++---
 gdb/testsuite/ChangeLog              |  4 ++++
 gdb/testsuite/gdb.ada/local-enum.exp |  5 +++++
 4 files changed, 32 insertions(+), 3 deletions(-)

-- 
2.26.2

Comments

Joel Brobecker Jan. 25, 2021, 7:57 a.m. | #1
Hi Tom,

> gdb/ChangeLog

> 2021-01-22  Tom Tromey  <tromey@adacore.com>

> 

> 	* ada-lang.c (resolve_subexp): Handle array context.

> 

> gdb/testsuite/ChangeLog

> 2021-01-22  Tom Tromey  <tromey@adacore.com>

> 

> 	* gdb.ada/local-enum.exp: Add enumerator resolution test.


Looks good to me as well. Thank you Tom.

-- 
Joel

Patch

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index e2befe1d82e..8d912402462 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -3474,6 +3474,12 @@  resolve_subexp (expression_up *expp, int *pos, int deprocedure_p,
   struct value **argvec;        /* Vector of operand types (alloca'ed).  */
   int nargs;                    /* Number of operands.  */
   int oplen;
+  /* If we're resolving an expression like ARRAY(ARG...), then we set
+     this to the type of the array, so we can use the index types as
+     the expected types for resolution.  */
+  struct type *array_type = nullptr;
+  /* The arity of ARRAY_TYPE.  */
+  int array_arity = 0;
 
   argvec = NULL;
   nargs = 0;
@@ -3490,7 +3496,12 @@  resolve_subexp (expression_up *expp, int *pos, int deprocedure_p,
       else
 	{
 	  *pos += 3;
-	  resolve_subexp (expp, pos, 0, NULL, parse_completion, tracker);
+	  struct value *lhs = resolve_subexp (expp, pos, 0, NULL,
+					      parse_completion, tracker);
+	  struct type *lhstype = ada_check_typedef (value_type (lhs));
+	  array_arity = ada_array_arity (lhstype);
+	  if (array_arity > 0)
+	    array_type = lhstype;
 	}
       nargs = longest_to_int (exp->elts[pc + 1].longconst);
       break;
@@ -3627,8 +3638,13 @@  resolve_subexp (expression_up *expp, int *pos, int deprocedure_p,
 
   argvec = XALLOCAVEC (struct value *, nargs + 1);
   for (i = 0; i < nargs; i += 1)
-    argvec[i] = resolve_subexp (expp, pos, 1, NULL, parse_completion,
-				tracker);
+    {
+      struct type *subtype = nullptr;
+      if (i < array_arity)
+	subtype = ada_index_type (array_type, i + 1, "array type");
+      argvec[i] = resolve_subexp (expp, pos, 1, subtype, parse_completion,
+				  tracker);
+    }
   argvec[i] = NULL;
   exp = expp->get ();
 
diff --git a/gdb/testsuite/gdb.ada/local-enum.exp b/gdb/testsuite/gdb.ada/local-enum.exp
index 32daf9a0d96..fc49bca1308 100644
--- a/gdb/testsuite/gdb.ada/local-enum.exp
+++ b/gdb/testsuite/gdb.ada/local-enum.exp
@@ -81,3 +81,8 @@  proc print_three {which_enum value} {
 
 print_three e2 0
 print_three e1 2
+
+# These will not result in a menu, as expression resolution should
+# disambiguate the meaning of 'three'.
+gdb_test "print v1(three)" " = 2" "print v1 element"
+gdb_test "print v2(three)" " = 3" "print v2 element"