[PATCH 1/3] Make "file" clear TUI source window

[Tom Tromey <tom@tromey.com>]

I noticed that a plain "file" will leave the current source file in
the TUI source window.  Instead, I think, it should clear the source
window.  This patch implements this.

2019-12-21  Tom Tromey  <tom@tromey.com>

	* tui/tui-winsource.c (tui_update_source_windows_with_line):
	Handle case where symtab is null.

gdb/testsuite/ChangeLog
2019-12-22  Tom Tromey  <tom@tromey.com>

	* gdb.tui/main.exp: Add check for plain "file".

Change-Id: I8424acf837f1a47f75bc6a833d1e917d4c10b51e
---
 gdb/ChangeLog                  |  5 +++++
 gdb/testsuite/ChangeLog        |  4 ++++
 gdb/testsuite/gdb.tui/main.exp |  7 +++++++
 gdb/tui/tui-winsource.c        | 11 ++++++-----
 4 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/gdb/testsuite/gdb.tui/main.exp b/gdb/testsuite/gdb.tui/main.exp
index 57ddb52bf36..b62e0f420d9 100644
--- a/gdb/testsuite/gdb.tui/main.exp
+++ b/gdb/testsuite/gdb.tui/main.exp
@@ -26,9 +26,16 @@ if {[build_executable "failed to prepare" ${testfile} ${srcfile}] == -1} {
 # Note: don't pass the executable here
 Term::clean_restart 24 80
 
+# Later on we'd like to avoid having to answer a question.
+gdb_test_no_output "set interactive-mode off"
+
 if {![Term::enter_tui]} {
     unsupported "TUI not supported"
 }
 
 Term::command "file [standard_output_file $testfile]"
 Term::check_contents "show main after file" "\\|.*21 *return 0"
+
+# Ensure that "file" clears the source window.
+Term::command "file"
+Term::check_contents "file clears window" "No Source Available"
diff --git a/gdb/tui/tui-winsource.c b/gdb/tui/tui-winsource.c
index 1ac650b6987..d720e99c6ab 100644
--- a/gdb/tui/tui-winsource.c
+++ b/gdb/tui/tui-winsource.c
@@ -212,11 +212,12 @@ tui_update_source_windows_with_addr (struct gdbarch *gdbarch, CORE_ADDR addr)
 void
 tui_update_source_windows_with_line (struct symtab_and_line sal)
 {
-  if (!sal.symtab)
-    return;
-
-  find_line_pc (sal.symtab, sal.line, &sal.pc);
-  struct gdbarch *gdbarch = get_objfile_arch (SYMTAB_OBJFILE (sal.symtab));
+  struct gdbarch *gdbarch = nullptr;
+  if (sal.symtab != nullptr)
+    {
+      find_line_pc (sal.symtab, sal.line, &sal.pc);
+      gdbarch = get_objfile_arch (SYMTAB_OBJFILE (sal.symtab));
+    }
 
   for (struct tui_source_window_base *win_info : tui_source_windows ())
     win_info->update_source_window (gdbarch, sal);
-- 
2.17.2