gdb: Don't store a thread-id for floating varobj

When creating a varobj with -var-create a user can create either fixed
varobj, or floating varobj.

A fixed varobj will always be evaluated within the thread/frame/block in
which the varobj was created, if that thread/frame/block is no longer
available then the varobj is considered out of scope.

A floating varobj will always be evaluated within the current
thread/frame/block.

Despite never using them GDB was storing the thread/frame/block into a
floating varobj, and the thread-id would then be displayed when GDB
reported on the state of the varobj, this could confuse a user into
thinking that the thread-id was relevant.

This commit prevents GDB storing the thread/frame/block onto floating
varobj, and updates the few tests where this impacts the results.

gdb/ChangeLog:

	* varobj.c (varobj_create): Don't set valid_block when creating a
	floating varobj.

gdb/testsuite/ChangeLog:

	* gdb.python/py-mi.exp: Don't expect a thread-id for floating
	varobj.
	* gdb.mi/mi-var-create-rtti.exp: Likewise.

5 files changed, 20 insertions, 8 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b982be1e57a..0661218bfcd 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2018-01-21  Andrew Burgess  <andrew.burgess@embecosm.com>
 
+	* varobj.c (varobj_create): Don't set valid_block when creating a
+	floating varobj.
+
+2018-01-21  Andrew Burgess  <andrew.burgess@embecosm.com>
+
 	* varobj.c (varobj_create): Remove out of date comment.
 
 2018-01-21  Andrew Burgess  <andrew.burgess@embecosm.com>
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 3a8e6ed30d2..72e1596731b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-21  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* gdb.python/py-mi.exp: Don't expect a thread-id for floating
+	varobj.
+	* gdb.mi/mi-var-create-rtti.exp: Likewise.
+
 2018-01-21  Don Breazeal  <donb@codesourcery.com>
 	    Andrew Burgess  <andrew.burgess@embecosm.com>
 
diff --git a/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp b/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
index 9ea5784bcad..a5310ecc819 100644
--- a/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
+++ b/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
@@ -52,6 +52,6 @@ mi_gdb_test "-var-create sp1 * ((void*)\$sp)" \
 	    "\\^done,name=\"sp1\",numchild=\"0\",value=\"$hex\",type=\"void \\*\",thread-id=\"$decimal\",has_more=\"0\"" \
 	    "-var-create sp1 * \$sp"
 mi_gdb_test "-var-create sp2 @ ((void*)\$sp)" \
-	    "\\^done,name=\"sp2\",numchild=\"0\",value=\"$hex\",type=\"void \\*\",thread-id=\"$decimal\",has_more=\"0\"" \
+	    "\\^done,name=\"sp2\",numchild=\"0\",value=\"$hex\",type=\"void \\*\",has_more=\"0\"" \
 	    "-var-create sp2 @ \$sp"
 gdb_exit
diff --git a/gdb/testsuite/gdb.python/py-mi.exp b/gdb/testsuite/gdb.python/py-mi.exp
index 0ecc5dfa13d..bbe1266724a 100644
--- a/gdb/testsuite/gdb.python/py-mi.exp
+++ b/gdb/testsuite/gdb.python/py-mi.exp
@@ -101,7 +101,7 @@ mi_varobj_update_dynamic container "varobj update 1" {
     type_changed false new_num_children 1 dynamic 1 has_more 0
 } {
 } {
-    { name {container.\[0\]} exp {\[0\]} numchild 0 type int thread-id 1 }
+    { name {container.\[0\]} exp {\[0\]} numchild 0 type int }
 }
 
 mi_next "next over update 2"
@@ -110,7 +110,7 @@ mi_varobj_update_dynamic container "varobj update 2" {
     type_changed false new_num_children 2 dynamic 1 has_more 0
 } {
 } {
-    { name {container.\[1\]} exp {\[1\]} numchild 0 type int thread-id 1 }
+    { name {container.\[1\]} exp {\[1\]} numchild 0 type int }
 }
 
 mi_gdb_test "-var-set-visualizer container None" \
@@ -129,8 +129,8 @@ mi_varobj_update_dynamic container "varobj update after choosing default" {
     type_changed false new_num_children 2 dynamic 1 has_more 0
 } {
 } {
-    { name {container.\[0\]} exp {\[0\]} numchild 0 type int thread-id 1 }
-    { name {container.\[1\]} exp {\[1\]} numchild 0 type int thread-id 1 }
+    { name {container.\[0\]} exp {\[0\]} numchild 0 type int }
+    { name {container.\[1\]} exp {\[1\]} numchild 0 type int }
 }
 
 mi_gdb_test "-var-set-visualizer container ContainerPrinter" \
@@ -142,8 +142,8 @@ mi_varobj_update_dynamic container \
       type_changed false new_num_children 2 dynamic 1 has_more 0
   } {
   } {
-      { name {container.\[0\]} exp {\[0\]} numchild 0 type int thread-id 1 }
-      { name {container.\[1\]} exp {\[1\]} numchild 0 type int thread-id 1 }
+      { name {container.\[0\]} exp {\[0\]} numchild 0 type int }
+      { name {container.\[1\]} exp {\[1\]} numchild 0 type int }
   }
 
 mi_list_varobj_children_range container 1 2 2 {
diff --git a/gdb/varobj.c b/gdb/varobj.c
index 523f74613bf..b6a2d8f3696 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -336,7 +336,8 @@ varobj_create (const char *objname,
 	}
 
       var->format = variable_default_display (var.get ());
-      var->root->valid_block = innermost_block.block ();
+      var->root->valid_block =
+	var->root->floating ? NULL : innermost_block.block ();
       var->name = expression;
       /* For a root var, the name and the expr are the same.  */
       var->path_expr = expression;