[PATCH] Fix type of values representing optimized out static members

[Simon Marchi <simon.marchi@ericsson.com>]

From: Simon Marchi <simark@simark.ca>

As reported here:

  https://sourceware.org/ml/gdb/2018-02/msg00019.html

the type of values representing static members that are optimized out is
wrong.  It currently assigns the type of the containing class rather
than the type of the field.  This patch fixes that.

I found a place in m-static.exp already dealing with optimized out
static members, so I just added some gdb_test there.

gdb/ChangeLog:

	* value.c (value_static_field): Assign field type instead of
	containing type when returning an optimized out value.

gdb/testsuite/ChangeLog:

	* gdb.cp/m-static.exp: Check type of optimized out static
	member.
---
 gdb/testsuite/gdb.cp/m-static.exp | 2 ++
 gdb/value.c                       | 8 +++-----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/gdb/testsuite/gdb.cp/m-static.exp b/gdb/testsuite/gdb.cp/m-static.exp
index 6566171..ffcbf53 100644
--- a/gdb/testsuite/gdb.cp/m-static.exp
+++ b/gdb/testsuite/gdb.cp/m-static.exp
@@ -165,6 +165,8 @@ if {[test_compiler_info {gcc-[0-3]-*}]
     setup_xfail *-*-*
 }
 gdb_test "print test4.nowhere" "<optimized out>" "static const int initialized nowhere (print field)"
+gdb_test "ptype test4.nowhere" "type = const int"
+gdb_test "print test4.nowhere.nowhere" "Attempt to extract a component of a value that is not a structure."
 
 # Same, but print the whole struct.
 gdb_test "print test4" "static nowhere = <optimized out>.*" "static const int initialized nowhere (whole struct)"
diff --git a/gdb/value.c b/gdb/value.c
index 9a144fb..9cd9a2f 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -2976,14 +2976,12 @@ value_static_field (struct type *type, int fieldno)
 	     reported as non-debuggable symbols.  */
 	  struct bound_minimal_symbol msym
 	    = lookup_minimal_symbol (phys_name, NULL, NULL);
+	  struct type *field_type = TYPE_FIELD_TYPE (type, fieldno);
 
 	  if (!msym.minsym)
-	    return allocate_optimized_out_value (type);
+	    retval = allocate_optimized_out_value (field_type);
 	  else
-	    {
-	      retval = value_at_lazy (TYPE_FIELD_TYPE (type, fieldno),
-				      BMSYMBOL_VALUE_ADDRESS (msym));
-	    }
+	    retval = value_at_lazy (field_type, BMSYMBOL_VALUE_ADDRESS (msym));
 	}
       else
 	retval = value_of_variable (sym.symbol, sym.block);
-- 
2.7.4