Make ctxobj.exp and print-file-var.exp work on all platforms.

This patch adjusts the testing strategy used in a couple of testcases
where we are trying to print the value of a global variable defined
at multiple locations.  The problem is that the actual value depends
on the platform.  So instead of hard-coding the expected value in
the testcase script, we use local variables (in the inferior) holding
the correct value, and we compare the global variable's value with
the local variable's value.

gdb/testsuite/ChangeLog:

        * gdb.base/ctxobj-f.c (GET_VERSION): Introduce local variable
        and add comment.
        * gdb.base/ctxobj-m.c (main): Rewrite, and add comment.
        * gdb.base/ctxobj.exp: Insert breakpoint in ctxobj-f.c using
        "STOP" marker.  Adjust testing strategy to make it work on
        all targets.

        * gdb.base/print-file-var-main.c (main): Rewrite using local
        variables and adjust get_version_2's return value check.
        Add small comment.
        * gdb.base/print-file-var.exp: Insert breakpoint using "STOP"
        marker.  Adjust testing strategy to make it work on all targets.

1 files changed, 35 insertions, 4 deletions

diff --git a/gdb/testsuite/gdb.base/print-file-var.exp b/gdb/testsuite/gdb.base/print-file-var.exp
index 67c3ac4..d0ab575 100644
--- a/gdb/testsuite/gdb.base/print-file-var.exp
+++ b/gdb/testsuite/gdb.base/print-file-var.exp
@@ -48,8 +48,39 @@ if ![runto_main] {
     return -1
 }
 
-gdb_test "print 'print-file-var-lib1.c'::this_version_id" \
-         " = 104"
+# Try printing "this_version_num" qualified with the name of the file
+# where the variables are defined.  There are two global variables
+# with that name, and some systems such as GNU/Linux merge them
+# into one single entity, while some other systems such as Windows
+# keep them separate.  In the first situation, we have to verify
+# that GDB does not randomly select the wrong instance, even when
+# a specific filename is used to qualified the lookup.  And in the
+# second case, we have to verify that GDB does select the instance
+# defined in the given filename.
+#
+# To avoid adding target-specific code in this testcase, the program
+# sets two local variable named 'v1' and 'v2' with the value of
+# our global variables.  This allows us to compare the value that
+# GDB returns for each query against the actual value seen by
+# the program itself.
+
+# Get past the initialization of variables 'v1' and 'v2'.
+
+set bp_location \
+    [gdb_get_line_number "STOP" "${executable}.c"]
+gdb_test "break $executable.c:$bp_location" \
+         "Breakpoint \[0-9\]+ at 0x\[0-9a-fA-F\]+: .*" \
+         "breapoint past v1 & v2 initialization"
+
+gdb_test "continue" \
+         "Breakpoint \[0-9\]+, main \\(\\) at.*" \
+         "continue to STOP marker"
+
+# Now check the value of this_version_id in both print-file-var-lib1.c
+# and print-file-var-lib2.c.
+
+gdb_test "print 'print-file-var-lib1.c'::this_version_id == v1" \
+         " = 1"
 
-gdb_test "print 'print-file-var-lib2.c'::this_version_id" \
-         " = 203"
+gdb_test "print 'print-file-var-lib2.c'::this_version_id == v2" \
+         " = 1"