[PATCH] [Ada] Fix completion for multiple function matches

[Pierre-Marie de Rodat <derodat at adacore dot com>]

Before this change, trying to complete an expression ending with an
ambiguous function name (i.e. for which there are multiple matches)
would display a menu with a prompt for the user to pick one. For
instance:

    (gdb) p func<tab>Multiple matches for func
    [0] cancel
    [1] pack2.func at pack2.adb:5
    [2] pack.func at pack.adb:5
    >

This is not user friendly and actually triggered a segmentation fault
after the user did pick one. It is not clear whether the segmentation
fault needs a separate fix, but this is the only known case which
exhibits it at the moment, and this case must be fixed itself.

The problem lies in ada-lang.c (ada_resolve_function): when we got
multiple matches, we should not display the menu if we are in completion
mode. This patch adjusts the corresponding condition accordingly.

gdb/ChangeLog:

	* ada-lang.c (ada_resolve_function): Do not ask the user what
	match to use when in completion mode.

gdb/testsuite/ChangeLog:

	* gdb.ada/complete.exp: Add "pck.ambiguous_func" to the relevant
	expected outputs.  Add two testcases for completing ambiguous
	functions.
	* gdb.ada/complete/aux_pck.adb: New file.
	* gdb.ada/complete/aux_pck.ads: New file.
	* gdb.ada/complete/foo.adb: Pull Aux_Pck and call the two
	Ambiguous_Func functions.
	* gdb.ada/complete/pck.ads: Add an Ambiguous_Func function.
	* gdb.ada/complete/pck.adb: Likewise.

Tested on x86_64-linux, no regression.
---
 gdb/ada-lang.c                             |  5 ++++-
 gdb/testsuite/gdb.ada/complete.exp         | 10 ++++++++++
 gdb/testsuite/gdb.ada/complete/aux_pck.adb | 23 +++++++++++++++++++++++
 gdb/testsuite/gdb.ada/complete/aux_pck.ads | 20 ++++++++++++++++++++
 gdb/testsuite/gdb.ada/complete/foo.adb     |  5 ++++-
 gdb/testsuite/gdb.ada/complete/pck.adb     |  5 +++++
 gdb/testsuite/gdb.ada/complete/pck.ads     |  2 ++
 7 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 gdb/testsuite/gdb.ada/complete/aux_pck.adb
 create mode 100644 gdb/testsuite/gdb.ada/complete/aux_pck.ads

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 7e6b6dc..6ee1028 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -3655,9 +3655,12 @@ ada_resolve_function (struct block_symbol syms[],
         }
     }
 
+  /* If we got multiple matches, ask the user which one to use.  Don't do this
+     interactive thing during completion, though: it is irritating to get a
+     prompt in this context.  */
   if (m == 0)
     return -1;
-  else if (m > 1)
+  else if (m > 1 && !parse_completion)
     {
       printf_filtered (_("Multiple matches for %s\n"), name);
       user_select_syms (syms, m, 1);
diff --git a/gdb/testsuite/gdb.ada/complete.exp b/gdb/testsuite/gdb.ada/complete.exp
index 9919bdf..8f4dedb 100644
--- a/gdb/testsuite/gdb.ada/complete.exp
+++ b/gdb/testsuite/gdb.ada/complete.exp
@@ -140,6 +140,7 @@ test_gdb_complete "external_ident" \
 test_gdb_complete "pck" \
                   [multi_line "(p pck\\.ad\[sb\])?" \
                               "(p pck\\.ad\[sb\])?" \
+                              "p pck.ambiguous_func" \
                               "p pck.external_identical_one" \
                               "p pck.inner.inside_variable" \
                               "p pck.local_identical_one" \
@@ -151,6 +152,7 @@ test_gdb_complete "pck" \
 test_gdb_complete "pck." \
                   [multi_line "(p pck\\.ad\[sb\])?" \
                               "(p pck\\.ad\[sb\])?" \
+                              "p pck.ambiguous_func" \
                               "p pck.external_identical_one" \
                               "p pck.inner.inside_variable" \
                               "p pck.local_identical_one" \
@@ -181,3 +183,11 @@ if { [readline_is_used] } {
 	}
     }
 }
+
+# Usually, parsing a function name that is ambiguous yields a menu through
+# which users can select a specific function. This should not happen during
+# completion, though.
+test_gdb_complete "ambig" \
+                  "p ambiguous_func"
+test_gdb_complete "ambiguous_func" \
+                  "p ambiguous_func"
diff --git a/gdb/testsuite/gdb.ada/complete/aux_pck.adb b/gdb/testsuite/gdb.ada/complete/aux_pck.adb
new file mode 100644
index 0000000..18e060e
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/complete/aux_pck.adb
@@ -0,0 +1,23 @@
+--  Copyright 2008-2015 Free Software Foundation, Inc.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 3 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package body Aux_Pck is
+
+   procedure Ambiguous_Func is
+   begin
+      null;
+   end Ambiguous_Func;
+
+end Aux_Pck;
diff --git a/gdb/testsuite/gdb.ada/complete/aux_pck.ads b/gdb/testsuite/gdb.ada/complete/aux_pck.ads
new file mode 100644
index 0000000..36fdb6c
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/complete/aux_pck.ads
@@ -0,0 +1,20 @@
+--  Copyright 2008-2015 Free Software Foundation, Inc.
+--
+--  This program is free software; you can redistribute it and/or modify
+--  it under the terms of the GNU General Public License as published by
+--  the Free Software Foundation; either version 3 of the License, or
+--  (at your option) any later version.
+--
+--  This program is distributed in the hope that it will be useful,
+--  but WITHOUT ANY WARRANTY; without even the implied warranty of
+--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+--  GNU General Public License for more details.
+--
+--  You should have received a copy of the GNU General Public License
+--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Aux_Pck is
+
+   procedure Ambiguous_Func;
+
+end Aux_Pck;
diff --git a/gdb/testsuite/gdb.ada/complete/foo.adb b/gdb/testsuite/gdb.ada/complete/foo.adb
index 58d0ee3..1d91f34 100644
--- a/gdb/testsuite/gdb.ada/complete/foo.adb
+++ b/gdb/testsuite/gdb.ada/complete/foo.adb
@@ -13,7 +13,8 @@
 --  You should have received a copy of the GNU General Public License
 --  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-with Pck; use Pck;
+with Aux_Pck; use Aux_Pck;
+with Pck;     use Pck;
 
 procedure Foo is
    Some_Local_Variable : Integer := 1;
@@ -21,5 +22,7 @@ procedure Foo is
 begin
    My_Global_Variable := Some_Local_Variable + 1; -- START
    Proc (External_Identical_Two);
+   Aux_Pck.Ambiguous_Func;
+   Pck.Ambiguous_Func;
 end Foo;
 
diff --git a/gdb/testsuite/gdb.ada/complete/pck.adb b/gdb/testsuite/gdb.ada/complete/pck.adb
index 51dd725..10680dc 100644
--- a/gdb/testsuite/gdb.ada/complete/pck.adb
+++ b/gdb/testsuite/gdb.ada/complete/pck.adb
@@ -21,4 +21,9 @@ package body Pck is
       Inner.Inside_Variable := Not_In_Scope + I;
    end Proc;
 
+   procedure Ambiguous_Func is
+   begin
+      null;
+   end Ambiguous_Func;
+
 end Pck;
diff --git a/gdb/testsuite/gdb.ada/complete/pck.ads b/gdb/testsuite/gdb.ada/complete/pck.ads
index ab2c47b..e85f566 100644
--- a/gdb/testsuite/gdb.ada/complete/pck.ads
+++ b/gdb/testsuite/gdb.ada/complete/pck.ads
@@ -31,4 +31,6 @@ package Pck is
 
    procedure Proc (I : Integer);
 
+   procedure Ambiguous_Func;
+
 end Pck;
-- 
2.4.6