Only use stride for final element type

A DWARF array type may specify a stride.  Currently, the DWARF reader
applies this stride to every dimension of an array.  However, this
seems incorrect to me -- only the innermost array ought to use the
stride, while outer arrays should compute a stride based on the size
of the inner arrays.  This patch arranges to apply the stride only to
the innermost array type.  This fixes a bug noticed when running some
Ada tests with -fgnat-encodings=minimal.

gdb/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* dwarf2/read.c (read_array_type): Only apply stride to innermost
	array.

gdb/testsuite/ChangeLog
2020-11-04  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/enum_idx_packed.exp: Add test.
	* gdb.ada/enum_idx_packed/foo.adb (Multi_Access):
	New variable.
	* gdb.ada/enum_idx_packed/pck.ads (Short)
	(Multi_Dimension, Multi_Dimension_Access): New types.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2020-11-04  Tom Tromey  <tromey@adacore.com>
+
+	* dwarf2/read.c (read_array_type): Only apply stride to innermost
+	array.
+
 2020-11-04  Tom Tromey  <tromey@adacore.com>
 
 	* gdbtypes.c (update_static_array_size): Handle bit stride.

gdb/dwarf2/read.c

@@ -17097,15 +17097,23 @@ read_array_type (struct die_info *die, struct dwarf2_cu *cu)
       int i = 0;
 
       while (i < range_types.size ())
-	type = create_array_type_with_stride (NULL, type, range_types[i++],
-					      byte_stride_prop, bit_stride);
+	{
+	  type = create_array_type_with_stride (NULL, type, range_types[i++],
+						byte_stride_prop, bit_stride);
+	  bit_stride = 0;
+	  byte_stride_prop = nullptr;
+	}
     }
   else
     {
       size_t ndim = range_types.size ();
       while (ndim-- > 0)
-	type = create_array_type_with_stride (NULL, type, range_types[ndim],
-					      byte_stride_prop, bit_stride);
+	{
+	  type = create_array_type_with_stride (NULL, type, range_types[ndim],
+						byte_stride_prop, bit_stride);
+	  bit_stride = 0;
+	  byte_stride_prop = nullptr;
+	}
     }
 
   /* Understand Dwarf2 support for vector types (like they occur on

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2020-11-04  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.ada/enum_idx_packed.exp: Add test.
+	* gdb.ada/enum_idx_packed/foo.adb (Multi_Access):
+	New variable.
+	* gdb.ada/enum_idx_packed/pck.ads (Short)
+	(Multi_Dimension, Multi_Dimension_Access): New types.
+
 2020-11-04  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.ada/enum_idx_packed.exp: Test two forms of -fgnat-encodings.

gdb/testsuite/gdb.ada/enum_idx_packed.exp

@@ -118,4 +118,7 @@ foreach_with_prefix scenario {all minimal} {
 	setup_kfail "minimal encodings" *-*-*
     }
     gdb_test "print multi_multi(2)" " = $matrix"
+
+    gdb_test "print multi_access.all" \
+	" = \\(\\(8, 13, 21, 34, 55\\), \\(1, 1, 2, 3, 5\\)\\)"
 }

gdb/testsuite/gdb.ada/enum_idx_packed/foo.adb

@@ -22,6 +22,10 @@ procedure Foo is
    Small : Small_Table := New_Small_Table (Low => Red, High => Green);
    Multi : Multi_Table := New_Multi_Table (Red, Green, Low, Medium);
    Multi_Multi : Multi_Multi_Table := New_Multi_Multi_Table (1, 2, 1, 7, 1, 10);
+   Multi_Access : Multi_Dimension_Access
+     := new Multi_Dimension'(True => (1, 1, 2, 3, 5),
+                             False => (8, 13, 21, 34, 55));
+
 begin
    Do_Nothing (Full'Address);  -- STOP
    Do_Nothing (Primary'Address);
@@ -29,4 +33,5 @@ begin
    Do_Nothing (Small'Address);
    Do_Nothing (Multi'Address);
    Do_Nothing (Multi_Multi'Address);
+   Do_Nothing (Multi_Access'Address);
 end Foo;

gdb/testsuite/gdb.ada/enum_idx_packed/pck.ads

@@ -17,6 +17,7 @@ with System;
 package Pck is
    type Color is (Black, Red, Green, Blue, White);
    type Strength is (None, Low, Medium, High);
+   type Short is new Natural range 0 .. 2 ** 8 - 1;
 
    type Full_Table is array (Color) of Boolean;
    pragma Pack (Full_Table);
@@ -43,5 +44,9 @@ package Pck is
    function New_Multi_Multi_Table (L1, H1, L2, H2, L3, H3: Positive)
       return Multi_Multi_Table;
 
+   type Multi_Dimension is array (Boolean, Color) of Short;
+   pragma Pack (Multi_Dimension);
+   type Multi_Dimension_Access is access all Multi_Dimension;
+
    procedure Do_Nothing (A : System.Address);
 end Pck;