[PATCH] PR cli/21688: Fix multi-line/inline command differentiation

[Sergio Durigan Junior <sergiodj at redhat dot com>]

This bug is a regression caused by the following commit:

  604c4576fdcfc4e7c28f569b3748a1b6b4e0dbd4 is the first bad commit
  commit 604c4576fdcfc4e7c28f569b3748a1b6b4e0dbd4
  Author: Jerome Guitton <guitton@adacore.com>
  Date:   Tue Jan 10 15:15:53 2017 +0100

The problem happens because, on cli/cli-script.c:process_next_line,
GDB is not using the command line string to identify which command to
run, but it instead using the 'struct cmd_list_element *' that is
obtained by using the mentioned string.  The problem with that is that
the 'struct cmd_list_element *' doesn't have any information on
whether the command issued by the user is a multi-line or inline one.

A multi-line command is a command that will necessarily be composed of
more than 1 line.  For example:

  (gdb) if 1
  >python
   >print ('hello')
   >end
  >end

As can be seen in the example above, the 'python' command actually
"opens" a new command line (represented by the change in the
indentation) that will then be used to enter Python code.  OTOH, an
inline command is a command that is "self-contained" in a single line,
for example:

  (gdb) if 1
  >python print ('hello')
  >end

This Python command is a one-liner, and therefore there is no other
Python code that can be entered for this same block.  There is also no
change in the indentation.

So, the fix is somewhat simple: we have to revert the change and use
the full command line string passed to process_next_line in order to
identify whether we're dealing with a multi-line or an inline command.
This commit does just that.  As can be seen, this regression also
affects other languages, like guile or the compile framework.  To make
things clearer, I decided to create a new helper function responsible
for identifying a non-inline command.

Testcase is attached.

gdb/ChangeLog:
2017-06-29  Sergio Durigan Junior  <sergiodj@redhat.com>

	PR cli/21688
	* cli/cli-script.c (command_name_equals_not_inline): New function.
	(process_next_line): Adjust 'if' clauses for "python", "compile"
	and "guile" to use command_name_equals_not_inline.

gdb/testsuite/ChangeLog:
2017-06-29  Sergio Durigan Junior  <sergiodj@redhat.com>

	PR cli/21688
	* gdb.python/py-cmd.exp (test_pr21688): New procedure.  Call it.
---
 gdb/ChangeLog                       |  7 +++++++
 gdb/cli/cli-script.c                | 21 +++++++++++++++++----
 gdb/testsuite/ChangeLog             |  5 +++++
 gdb/testsuite/gdb.python/py-cmd.exp | 30 ++++++++++++++++++++++++++++++
 4 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a82026f..194cda8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2017-06-29  Sergio Durigan Junior  <sergiodj@redhat.com>
+
+	PR cli/21688
+	* cli/cli-script.c (command_name_equals_not_inline): New function.
+	(process_next_line): Adjust 'if' clauses for "python", "compile"
+	and "guile" to use command_name_equals_not_inline.
+
 2017-06-28  Pedro Alves  <palves@redhat.com>
 
 	* command.h: Include "common/scoped_restore.h".
diff --git a/gdb/cli/cli-script.c b/gdb/cli/cli-script.c
index e0e27ef..72f316f 100644
--- a/gdb/cli/cli-script.c
+++ b/gdb/cli/cli-script.c
@@ -900,6 +900,20 @@ command_name_equals (struct cmd_list_element *cmd, const char *name)
 	  && strcmp (cmd->name, name) == 0);
 }
 
+/* Return true if NAME is the only command between COMMAND_START and
+   COMMAND_END.  This is useful when we want to know whether the
+   command is inline (i.e., has arguments like 'python command1') or
+   is the start of a multi-line command block.  */
+
+static bool
+command_name_equals_not_inline (const char *command_start,
+				const char *command_end,
+				const char *name)
+{
+  return (command_end - command_start == strlen (name)
+	  && startswith (command_start, name));
+}
+
 /* Given an input line P, skip the command and return a pointer to the
    first argument.  */
 
@@ -997,21 +1011,20 @@ process_next_line (char *p, struct command_line **command, int parse_commands,
 	{
 	  *command = build_command_line (commands_control, line_first_arg (p));
 	}
-      else if (command_name_equals (cmd, "python"))
+      else if (command_name_equals_not_inline (p_start, p_end, "python"))
 	{
 	  /* Note that we ignore the inline "python command" form
 	     here.  */
 	  *command = build_command_line (python_control, "");
 	}
-      else if (command_name_equals (cmd, "compile"))
+      else if (command_name_equals_not_inline (p_start, p_end, "compile"))
 	{
 	  /* Note that we ignore the inline "compile command" form
 	     here.  */
 	  *command = build_command_line (compile_control, "");
 	  (*command)->control_u.compile.scope = COMPILE_I_INVALID_SCOPE;
 	}
-
-      else if (command_name_equals (cmd, "guile"))
+      else if (command_name_equals_not_inline (p_start, p_end, "guile"))
 	{
 	  /* Note that we ignore the inline "guile command" form here.  */
 	  *command = build_command_line (guile_control, "");
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index b7462a5..ef46a5d 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-06-29  Sergio Durigan Junior  <sergiodj@redhat.com>
+
+	PR cli/21688
+	* gdb.python/py-cmd.exp (test_pr21688): New procedure.  Call it.
+
 2017-06-28  Doug Gilmore  <Doug.Gilmore@imgtec.com>
 
 	PR gdb/21337
diff --git a/gdb/testsuite/gdb.python/py-cmd.exp b/gdb/testsuite/gdb.python/py-cmd.exp
index 2dbf23ce..052afa4 100644
--- a/gdb/testsuite/gdb.python/py-cmd.exp
+++ b/gdb/testsuite/gdb.python/py-cmd.exp
@@ -181,6 +181,36 @@ gdb_test "complete expr_test bar\." \
     "expr_test bar\.bc.*expr_test bar\.ij.*" \
     "test completion through complete command"
 
+# Testing PR cli/21688.  This is not language-specific, but the
+# easiest way is just to test with Python.
+proc test_pr21688 { } {
+    set define_cmd_not_inline {
+	{ "if 1" " >$" }
+	{ "python" " >$" }
+	{ "print ('hello')" "  >$" }
+	{ "end" " >$" }
+	{ "end" "hello\r\n" } }
+
+    set define_cmd_inline {
+	{ "if 1" " >$" }
+	{ "python print ('hello')" " >$" }
+	{ "end" "hello\r\n" } }
+
+    foreach t [list $define_cmd_not_inline $define_cmd_inline] {
+	foreach l $t {
+	    foreach { command regex } $l {
+		gdb_test_multiple "$command" "$command" {
+		    -re "$regex" {
+			pass "$command"
+		    }
+		}
+	    }
+	}
+    }
+}
+
+test_pr21688
+
 if { [readline_is_used] } {
     set test "complete 'expr_test bar.i'"
     send_gdb "expr_test bar\.i\t\t"
-- 
2.9.3