[vala] Do not declare result variable if it is unused

[Jürg Billeter <juergbi src gnome org>]

commit 4cdf4417a4422182f5336a3c181e7940fdedc341
Author: Jürg Billeter <j bitron ch>
Date:   Wed Sep 16 14:15:29 2009 +0200

    Do not declare result variable if it is unused

 codegen/valaccodebasemodule.vala   |    9 ++++++---
 codegen/valaccodemethodmodule.vala |    9 ++++++---
 2 files changed, 12 insertions(+), 6 deletions(-)
---
diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 9f5611d..5063d38 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -1517,9 +1517,12 @@ internal class Vala.CCodeBaseModule : CCodeModule {
 			}
 
 			if (acc.readable && !returns_real_struct) {
-				var cdecl = new CCodeDeclaration (acc.value_type.get_cname ());
-				cdecl.add_declarator (new CCodeVariableDeclarator ("result"));
-				function.block.prepend_statement (cdecl);
+				// do not declare result variable if exit block is known to be unreachable
+				if (acc.exit_block == null || acc.exit_block.get_predecessors ().size > 0) {
+					var cdecl = new CCodeDeclaration (acc.value_type.get_cname ());
+					cdecl.add_declarator (new CCodeVariableDeclarator ("result"));
+					function.block.prepend_statement (cdecl);
+				}
 			}
 
 			if (current_method_inner_error) {
diff --git a/codegen/valaccodemethodmodule.vala b/codegen/valaccodemethodmodule.vala
index 3125e74..2eb974b 100644
--- a/codegen/valaccodemethodmodule.vala
+++ b/codegen/valaccodemethodmodule.vala
@@ -492,9 +492,12 @@ internal class Vala.CCodeMethodModule : CCodeStructModule {
 				}
 
 				if (!(m.return_type is VoidType) && !m.return_type.is_real_struct_type () && !m.coroutine) {
-					var cdecl = new CCodeDeclaration (m.return_type.get_cname ());
-					cdecl.add_declarator (new CCodeVariableDeclarator ("result"));
-					cinit.append (cdecl);
+					// do not declare result variable if exit block is known to be unreachable
+					if (m.exit_block == null || m.exit_block.get_predecessors ().size > 0) {
+						var cdecl = new CCodeDeclaration (m.return_type.get_cname ());
+						cdecl.add_declarator (new CCodeVariableDeclarator ("result"));
+						cinit.append (cdecl);
+					}
 				}
 
 				if (inner_error) {