Changed the grammar for out parameters to deprecate the semicolon syntax

    and use an "out" keyword instead. The old syntax still works, but now
    prints a warning. Fixed up all the test cases that got broken by this
    and add a new test case for out-of-order in and out parameters.
    Refactored the grammar somewhat because, initially, out params added
    something like 50 shift/reduce conflicts. One shift/reduce conflict
    remains, caused by the addition of ICE_OUT to the last production in
    Grammar.y. We could avoid the conflict by removing ICE_OUT from that
    production, but then we wouldn't catch other errors anymore, such as an
    attempt to use "out" as the name of an operation or interface. I've
    added a warning to the Makefile to expect 1 shift/reduce conflict when
    Grammar.y is rebuilt.

5 files changed, 97 insertions, 23 deletions

diff --git a/cpp/src/Slice/Grammar.y b/cpp/src/Slice/Grammar.y
index 58abb4fc474..7fb37c3af41 100644
--- a/cpp/src/Slice/Grammar.y
+++ b/cpp/src/Slice/Grammar.y
@@ -43,6 +43,7 @@ yyerror(const char* s)
 %token ICE_SEQUENCE
 %token ICE_DICTIONARY
 %token ICE_ENUM
+%token ICE_OUT
 %token ICE_EXTENDS
 %token ICE_IMPLEMENTS
 %token ICE_THROWS
@@ -819,43 +820,60 @@ operation
 ;
  
 // ----------------------------------------------------------------------
-parameters
+param_decl
 // ----------------------------------------------------------------------
-: type ICE_IDENTIFIER ',' parameters
+: type ICE_IDENTIFIER
 {
     TypePtr type = TypePtr::dynamicCast($1);
     StringTokPtr ident = StringTokPtr::dynamicCast($2);
-    TypeStringListTokPtr parms = TypeStringListTokPtr::dynamicCast($4);
-    parms->v.push_front(make_pair(type, ident->v));
-    $$ = parms;
+    TypeStringTokPtr typestring = new TypeStringTok;
+    typestring->v = make_pair(type, ident->v);
+    $$ = typestring;
 }
-| type ICE_IDENTIFIER
+| type keyword
+{
+    unit->error("keyword cannot be used as a parameter name");
+    $$ = new TypeStringTok;
+}
+| type
 {
     TypePtr type = TypePtr::dynamicCast($1);
-    StringTokPtr ident = StringTokPtr::dynamicCast($2);
-    TypeStringListTokPtr parms = new TypeStringListTok;
-    parms->v.push_front(make_pair(type, ident->v));
-    $$ = parms;
+    unit->error("missing parameter name");
+    $$ = new TypeStringTok;
 }
-| type ',' parameters
+;
+
+// ----------------------------------------------------------------------
+out_param_decl
+// ----------------------------------------------------------------------
+: ICE_OUT param_decl
 {
-    unit->error("missing declarator");
-    $$ = $3
+    $$ = $2;
 }
-| type
+|
+out_param_decl ',' param_decl
 {
-    unit->error("missing declarator");
-    $$ = new TypeStringListTok;
+    unit->error("in parameters cannot follow out parameters");
+    $$ = $1;
 }
-| type keyword ',' parameters
+;
+
+// ----------------------------------------------------------------------
+parameters
+// ----------------------------------------------------------------------
+:  param_decl ',' parameters
 {
-    unit->error("keyword cannot be used as declarator");
-    $$ = $4
+    TypeStringListTokPtr parms = TypeStringListTokPtr::dynamicCast($3);
+    TypeStringTokPtr typestring = TypeStringTokPtr::dynamicCast($1);
+    parms->v.push_front(typestring->v);
+    $$ = parms;
 }
-| type keyword
+| param_decl
 {
-    unit->error("keyword cannot be used as declarator");
-    $$ = new TypeStringListTok;
+    TypeStringTokPtr typestring = TypeStringTokPtr::dynamicCast($1);
+    TypeStringListTokPtr parms = new TypeStringListTok;
+    parms->v.push_front(typestring->v);
+    $$ = parms;
 }
 |
 {
@@ -866,10 +884,33 @@ parameters
 // ----------------------------------------------------------------------
 output_parameters
 // ----------------------------------------------------------------------
+
+//
+// TODO: remove the first rule before releasing stable_39 -- the syntax
+// for out parameters has changed to use the out keyword, and the
+// semicolon syntax is deprecated for stable_38, to be removed with
+// stable_39.
+//
 : ';' parameters
 {
+    unit->warning("Deprecated use of semicolon to indicate out parameters");
+    unit->warning("Use the out keyword instead");
     $$ = $2
 }
+| out_param_decl ',' output_parameters
+{
+    TypeStringListTokPtr parms = TypeStringListTokPtr::dynamicCast($3);
+    TypeStringTokPtr typestring = TypeStringTokPtr::dynamicCast($1);
+    parms->v.push_front(typestring->v);
+    $$ = parms;
+}
+| out_param_decl
+{
+    TypeStringTokPtr typestring = TypeStringTokPtr::dynamicCast($1);
+    TypeStringListTokPtr parms = new TypeStringListTok;
+    parms->v.push_front(typestring->v);
+    $$ = parms;
+}
 |
 {
     $$ = new TypeStringListTok;
@@ -1126,6 +1167,9 @@ keyword
 | ICE_ENUM
 {
 }
+| ICE_OUT
+{
+}
 ;
 
 %%
diff --git a/cpp/src/Slice/GrammarUtil.h b/cpp/src/Slice/GrammarUtil.h
index 3d64d605fbd..0d510e7e3d3 100644
--- a/cpp/src/Slice/GrammarUtil.h
+++ b/cpp/src/Slice/GrammarUtil.h
@@ -17,6 +17,7 @@ namespace Slice
 {
 
 class StringTok;
+class TypeStringTok;
 class TypeStringListTok;
 class StringListTok;
 class BoolTok;
@@ -25,6 +26,7 @@ class ClassListTok;
 class EnumeratorListTok;
 
 typedef ::IceUtil::Handle<StringTok> StringTokPtr;
+typedef ::IceUtil::Handle<TypeStringTok> TypeStringTokPtr;
 typedef ::IceUtil::Handle<TypeStringListTok> TypeStringListTokPtr;
 typedef ::IceUtil::Handle<StringListTok> StringListTokPtr;
 typedef ::IceUtil::Handle<BoolTok> BoolTokPtr;
@@ -45,6 +47,18 @@ public:
 };
 
 // ----------------------------------------------------------------------
+// TypeStringTok
+// ----------------------------------------------------------------------
+
+class SLICE_API TypeStringTok : public GrammarBase
+{
+public:
+
+    TypeStringTok() { }
+    TypeString v;
+};
+
+// ----------------------------------------------------------------------
 // TypeStringListTok
 // ----------------------------------------------------------------------
 
diff --git a/cpp/src/Slice/Makefile b/cpp/src/Slice/Makefile
index a9ada1884c5..cbb7f7e2cf0 100644
--- a/cpp/src/Slice/Makefile
+++ b/cpp/src/Slice/Makefile
@@ -39,6 +39,7 @@ $(NAME): $(VERSIONED_NAME)
 	ln -s $(VERSIONED_BASE) $@
 
 Grammar.cpp Grammar.h: Grammar.y
+	@echo "Expect 1 shift/reduce conflict"
 	bison -dvt Grammar.y
 	rm -f Grammar.cpp ; mv Grammar.tab.c Grammar.cpp
 	rm -f Grammar.h ; mv Grammar.tab.h Grammar.h
diff --git a/cpp/src/Slice/Parser.cpp b/cpp/src/Slice/Parser.cpp
index cea765dc172..8fd318910e1 100644
--- a/cpp/src/Slice/Parser.cpp
+++ b/cpp/src/Slice/Parser.cpp
@@ -1352,7 +1352,14 @@ Slice::ClassDef::createOperation(const string& name,
 	    ++q;
 	    while (q != allParams.end())
 	    {
-		if (p->second == q->second)
+		//
+		// Complain about duplicate parameters only if they are
+		// non-empty; otherwise, we get a complaint about duplicates
+		// if two or more parameter names are missing in an operation
+		// signature (but the missing parameters have been reported
+		// already).
+		//
+		if (p->second == q->second && p->second != "")
 		{
 		    string msg = "duplicate parameter `";
 		    msg += p->second;
diff --git a/cpp/src/Slice/Scanner.l b/cpp/src/Slice/Scanner.l
index 93e87e77506..584fcadb877 100644
--- a/cpp/src/Slice/Scanner.l
+++ b/cpp/src/Slice/Scanner.l
@@ -231,6 +231,14 @@ using namespace Slice;
     return ICE_OP_KEYWORD;
 }
 
+"out" {
+    return ICE_OUT;
+}
+
+"out"[[:space:]]*"(" {
+    return ICE_OP_KEYWORD;
+}
+
 "extends" {
     return ICE_EXTENDS;
 }