Semantics: Geometry stage can support max_vertices = 0.

To do this, more generally use a named -1 as a not set value.

Test/420.tesc

@@ -38,4 +38,6 @@ void foo()
     {
         ;
     }
-}
+}
+
+layout(vertices = 0) out;  // ERROR, can't be 0

Test/baseResults/150.tesc.out

@@ -586,7 +586,7 @@ ERROR: 1 compilation errors.  No code generated.
 
 
 Shader version: 400
-vertices = 0
+vertices = -1
 ERROR: node is still EOpNull!
 0:8  Function Definition: main( (global void)
 0:8    Function Parameters: 
@@ -603,7 +603,8 @@ ERROR: 0:12: 'vertices' : inconsistent output number of vertices for array size
 ERROR: 0:26: 'gl_PointSize' : no such field in structure 
 ERROR: 0:26: 'assign' :  cannot convert from 'temp float' to 'temp block{out 4-component vector of float Position gl_Position}'
 ERROR: 0:29: 'out' : type must be an array: outf
-ERROR: 6 compilation errors.  No code generated.
+ERROR: 0:43: 'vertices' : must be greater than 0 
+ERROR: 7 compilation errors.  No code generated.
 
 
 Shader version: 420

Test/baseResults/410.geom.out

@@ -13,7 +13,7 @@ ERROR: 7 compilation errors.  No code generated.
 
 Shader version: 410
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = none
 ERROR: node is still EOpNull!
@@ -66,7 +66,7 @@ ERROR: Linking geometry stage: At least one shader must specify a layout(max_ver
 
 Shader version: 410
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = none
 ERROR: node is still EOpNull!

Test/baseResults/410.tesc.out

@@ -5,7 +5,7 @@ ERROR: 1 compilation errors.  No code generated.
 
 
 Shader version: 400
-vertices = 0
+vertices = -1
 ERROR: node is still EOpNull!
 0:8  Function Definition: main( (global void)
 0:8    Function Parameters: 
@@ -20,7 +20,7 @@ Linked tessellation control stage:
 ERROR: Linking tessellation control stage: At least one shader must specify an output layout(vertices=...)
 
 Shader version: 400
-vertices = 0
+vertices = -1
 ERROR: node is still EOpNull!
 0:8  Function Definition: main( (global void)
 0:8    Function Parameters: 

Test/baseResults/420.geom.out

@@ -11,7 +11,7 @@ ERROR: 6 compilation errors.  No code generated.
 
 Shader version: 420
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = triangles
 output primitive = none
 ERROR: node is still EOpNull!
@@ -138,7 +138,7 @@ ERROR: Linking geometry stage: At least one shader must specify a layout(max_ver
 
 Shader version: 420
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = triangles
 output primitive = none
 ERROR: node is still EOpNull!

Test/baseResults/420.tesc.out

@@ -6,7 +6,8 @@ ERROR: 0:12: 'vertices' : inconsistent output number of vertices for array size
 ERROR: 0:26: 'gl_PointSize' : no such field in structure 
 ERROR: 0:26: 'assign' :  cannot convert from 'temp float' to 'temp block{out 4-component vector of float Position gl_Position}'
 ERROR: 0:29: 'out' : type must be an array: outf
-ERROR: 6 compilation errors.  No code generated.
+ERROR: 0:43: 'vertices' : must be greater than 0 
+ERROR: 7 compilation errors.  No code generated.
 
 
 Shader version: 420

Test/baseResults/420_size_gl_in.geom.out

@@ -6,7 +6,7 @@ ERROR: 1 compilation errors.  No code generated.
 
 Shader version: 420
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = triangles
 output primitive = none
 ERROR: node is still EOpNull!
@@ -45,7 +45,7 @@ ERROR: Linking geometry stage: At least one shader must specify a layout(max_ver
 
 Shader version: 420
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = triangles
 output primitive = none
 ERROR: node is still EOpNull!

Test/baseResults/450.geom.out

@@ -3,7 +3,7 @@ Warning, version 450 is not yet complete; most version-specific features are pre
 
 Shader version: 450
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = none
 0:? Sequence
@@ -41,7 +41,7 @@ ERROR: Linking geometry stage: At least one shader must specify a layout(max_ver
 
 Shader version: 450
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = none
 0:? Sequence

Test/baseResults/450.tesc.out

@@ -2,7 +2,7 @@
 Warning, version 450 is not yet complete; most version-specific features are present, but some are missing.
 
 Shader version: 450
-vertices = 0
+vertices = -1
 0:? Sequence
 0:11  Function Definition: main( (global void)
 0:11    Function Parameters: 
@@ -37,7 +37,7 @@ Linked tessellation control stage:
 ERROR: Linking tessellation control stage: At least one shader must specify an output layout(vertices=...)
 
 Shader version: 450
-vertices = 0
+vertices = -1
 0:? Sequence
 0:11  Function Definition: main( (global void)
 0:11    Function Parameters: 

Test/baseResults/mains1.frag.out

@@ -19,7 +19,7 @@ ERROR: 1 compilation errors.  No code generated.
 
 Shader version: 150
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = points
 ERROR: node is still EOpNull!
@@ -30,7 +30,7 @@ ERROR: node is still EOpNull!
 noMain2.geom
 Shader version: 150
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = line_strip
 0:? Sequence
@@ -53,7 +53,7 @@ ERROR: Linking fragment stage: Multiple function bodies in multiple compilation
 
 Shader version: 150
 invocations = 0
-max_vertices = 0
+max_vertices = -1
 input primitive = none
 output primitive = points
 ERROR: node is still EOpNull!

Test/baseResults/max_vertices_0.geom.out

@@ -0,0 +1,35 @@
+max_vertices_0.geom
+Shader version: 330
+invocations = 0
+max_vertices = 0
+input primitive = points
+output primitive = triangle_strip
+0:? Sequence
+0:8  Function Definition: main( (global void)
+0:8    Function Parameters: 
+0:10    Sequence
+0:10      EndPrimitive (global void)
+0:11      EndPrimitive (global void)
+0:?   Linker Objects
+0:?     'v_geom_FragColor' (in 1-element array of 4-component vector of float)
+0:?     'v_frag_FragColor' (layout(stream=0 ) out 4-component vector of float)
+
+
+Linked geometry stage:
+
+
+Shader version: 330
+invocations = 0
+max_vertices = 0
+input primitive = points
+output primitive = triangle_strip
+0:? Sequence
+0:8  Function Definition: main( (global void)
+0:8    Function Parameters: 
+0:10    Sequence
+0:10      EndPrimitive (global void)
+0:11      EndPrimitive (global void)
+0:?   Linker Objects
+0:?     'v_geom_FragColor' (in 1-element array of 4-component vector of float)
+0:?     'v_frag_FragColor' (layout(stream=0 ) out 4-component vector of float)
+

Test/max_vertices_0.geom

@@ -0,0 +1,12 @@
+#version 330
+
+layout(points) in;
+layout(triangle_strip, max_vertices = 0) out;
+in highp vec4 v_geom_FragColor[];
+out highp vec4 v_frag_FragColor;
+
+void main (void)
+{
+    EndPrimitive();
+    EndPrimitive();
+}

Test/runtests

@@ -84,6 +84,7 @@ runBulkTest 300link2.frag
 runBulkTest 300link3.frag
 runBulkTest empty.frag empty2.frag empty3.frag
 runBulkTest 150.tesc 150.tese 400.tesc 400.tese 410.tesc 420.tesc 420.tese
+runBulkTest max_vertices_0.geom
 
 #
 # reflection tests

glslang/Include/Types.h

@@ -327,6 +327,8 @@ enum TBlendEquationShift {
 
 class TQualifier {
 public:
+    static const int layoutNotSet = -1;
+
     void clear()
     {
         precision = EpqNone;
@@ -489,8 +491,8 @@ public:
     {
         layoutMatrix = ElmNone;
         layoutPacking = ElpNone;
-        layoutOffset = -1;
+        layoutOffset = layoutNotSet;
-        layoutAlign = -1;
+        layoutAlign = layoutNotSet;
 
         layoutLocation = layoutLocationEnd;
         layoutComponent = layoutComponentEnd;
@@ -567,11 +569,11 @@ public:
     }
     bool hasOffset() const
     {
-        return layoutOffset != -1;
+        return layoutOffset != layoutNotSet;
     }
     bool hasAlign() const
     {
-        return layoutAlign != -1;
+        return layoutAlign != layoutNotSet;
     }
     bool hasAnyLocation() const
     {
@@ -789,7 +791,7 @@ struct TShaderQualifiers {
         originUpperLeft = false;
         pixelCenterInteger = false;
         invocations = 0;        // 0 means no declaration
-        vertices = 0;
+        vertices = TQualifier::layoutNotSet;
         spacing = EvsNone;
         order = EvoNone;
         pointMode = false;
@@ -813,7 +815,7 @@ struct TShaderQualifiers {
             originUpperLeft = src.originUpperLeft;
         if (src.invocations != 0)
             invocations = src.invocations;
-        if (src.vertices != 0)
+        if (src.vertices != TQualifier::layoutNotSet)
             vertices = src.vertices;
         if (src.spacing != EvsNone)
             spacing = src.spacing;

glslang/Include/revision.h

@@ -2,5 +2,5 @@
 // For the version, it uses the latest git tag followed by the number of commits.
 // For the date, it uses the current date (when then script is run).
 
-#define GLSLANG_REVISION "SPIRV99.839"
+#define GLSLANG_REVISION "SPIRV99.841"
 #define GLSLANG_DATE "11-Dec-2015"

glslang/MachineIndependent/ParseHelper.cpp

@@ -662,7 +662,7 @@ void TParseContext::handleIoResizeArrayAccess(const TSourceLoc& /*loc*/, TInterm
     // fix array size, if it can be fixed and needs to be fixed (will allow variable indexing)
     if (symbolNode->getType().isImplicitlySizedArray()) {
         int newSize = getIoArrayImplicitSize();
-        if (newSize)
+        if (newSize > 0)
             symbolNode->getWritableType().changeOuterArraySize(newSize);
     }
 }
@@ -703,7 +703,7 @@ int TParseContext::getIoArrayImplicitSize() const
     if (language == EShLangGeometry)
         return TQualifier::mapGeometryToSize(intermediate.getInputPrimitive());
     else if (language == EShLangTessControl)
-        return intermediate.getVertices();
+        return intermediate.getVertices() != TQualifier::layoutNotSet ? intermediate.getVertices() : 0;
     else
         return 0;
 }
@@ -3875,7 +3875,10 @@ void TParseContext::setLayoutQualifier(const TSourceLoc& loc, TPublicType& publi
 
     case EShLangTessControl:
         if (id == "vertices") {
-            publicType.shaderQualifiers.vertices = value;
+            if (value == 0)
+                error(loc, "must be greater than 0", "vertices", "");
+            else
+                publicType.shaderQualifiers.vertices = value;
             return;
         }
         break;
@@ -4275,7 +4278,7 @@ void TParseContext::checkNoShaderLayouts(const TSourceLoc& loc, const TShaderQua
         error(loc, message, TQualifier::getGeometryString(shaderQualifiers.geometry), "");
     if (shaderQualifiers.invocations > 0)
         error(loc, message, "invocations", "");
-    if (shaderQualifiers.vertices > 0) {
+    if (shaderQualifiers.vertices != TQualifier::layoutNotSet) {
         if (language == EShLangGeometry)
             error(loc, message, "max_vertices", "");
         else if (language == EShLangTessControl)
@@ -5438,7 +5441,7 @@ void TParseContext::invariantCheck(const TSourceLoc& loc, const TQualifier& qual
 //
 void TParseContext::updateStandaloneQualifierDefaults(const TSourceLoc& loc, const TPublicType& publicType)
 {
-    if (publicType.shaderQualifiers.vertices) {
+    if (publicType.shaderQualifiers.vertices != TQualifier::layoutNotSet) {
         assert(language == EShLangTessControl || language == EShLangGeometry);
         const char* id = (language == EShLangTessControl) ? "vertices" : "max_vertices";
 

glslang/MachineIndependent/linkValidate.cpp

@@ -100,7 +100,7 @@ void TIntermediate::merge(TInfoSink& infoSink, TIntermediate& unit)
     else if (outputPrimitive != unit.outputPrimitive)
         error(infoSink, "Contradictory output layout primitives");
     
-    if (vertices == 0)
+    if (vertices == TQualifier::layoutNotSet)
         vertices = unit.vertices;
     else if (vertices != unit.vertices) {
         if (language == EShLangGeometry)
@@ -409,7 +409,7 @@ void TIntermediate::finalCheck(TInfoSink& infoSink)
     case EShLangVertex:
         break;
     case EShLangTessControl:
-        if (vertices == 0)
+        if (vertices == TQualifier::layoutNotSet)
             error(infoSink, "At least one shader must specify an output layout(vertices=...)");
         break;
     case EShLangTessEvaluation:
@@ -425,7 +425,7 @@ void TIntermediate::finalCheck(TInfoSink& infoSink)
             error(infoSink, "At least one shader must specify an input layout primitive");
         if (outputPrimitive == ElgNone)
             error(infoSink, "At least one shader must specify an output layout primitive");
-        if (vertices == 0)
+        if (vertices == TQualifier::layoutNotSet)
             error(infoSink, "At least one shader must specify a layout(max_vertices = value)");
         break;
     case EShLangFragment:

glslang/MachineIndependent/localintermediate.h

@@ -126,7 +126,7 @@ class TIntermediate {
 public:
     explicit TIntermediate(EShLanguage l, int v = 0, EProfile p = ENoProfile) : language(l), treeRoot(0), profile(p), version(v), spv(0),
         numMains(0), numErrors(0), recursive(false),
-        invocations(0), vertices(0), inputPrimitive(ElgNone), outputPrimitive(ElgNone), pixelCenterInteger(false), originUpperLeft(false),
+        invocations(0), vertices(TQualifier::layoutNotSet), inputPrimitive(ElgNone), outputPrimitive(ElgNone), pixelCenterInteger(false), originUpperLeft(false),
         vertexSpacing(EvsNone), vertexOrder(EvoNone), pointMode(false), earlyFragmentTests(false), depthLayout(EldNone), depthReplacing(false), blendEquations(0), xfbMode(false)
     {
         localSize[0] = 1;
@@ -212,7 +212,7 @@ public:
     int getInvocations() const { return invocations; }
     bool setVertices(int m)
     {
-        if (vertices > 0)
+        if (vertices != TQualifier::layoutNotSet)
             return vertices == m;
         vertices = m;
         return true;