Require fixed workgroup size declaration

Fix 2479.

glslang/MachineIndependent/ParseHelper.cpp

@@ -2756,6 +2756,11 @@ void TParseContext::rValueErrorCheck(const TSourceLoc& loc, const char* op, TInt
     if (!(symNode && symNode->getQualifier().isWriteOnly())) // base class checks
         if (symNode && symNode->getQualifier().isExplicitInterpolation())
             error(loc, "can't read from explicitly-interpolated object: ", op, symNode->getName().c_str());
+
+    // local_size_{xyz} must be assigned or specialized before gl_WorkGroupSize can be assigned. 
+    if(node->getQualifier().builtIn == EbvWorkGroupSize &&
+       !(intermediate.isLocalSizeSet() || intermediate.isLocalSizeSpecialized()))
+        error(loc, "can't read from gl_WorkGroupSize before a fixed workgroup size has been declared", op, "");
 }
 
 //

glslang/MachineIndependent/localintermediate.h

@@ -550,6 +550,11 @@ public:
         return true;
     }
     unsigned int getLocalSize(int dim) const { return localSize[dim]; }
+    bool isLocalSizeSet() const
+    {
+        // Return true if any component has been set (i.e. any component is not default).
+        return localSizeNotDefault[0] || localSizeNotDefault[1] || localSizeNotDefault[2];
+    }
     bool setLocalSizeSpecId(int dim, int id)
     {
         if (localSizeSpecId[dim] != TQualifier::layoutNotSet)
@@ -558,6 +563,13 @@ public:
         return true;
     }
     int getLocalSizeSpecId(int dim) const { return localSizeSpecId[dim]; }
+    bool isLocalSizeSpecialized() const
+    {
+        // Return true if any component has been specialized.
+        return localSizeSpecId[0] != TQualifier::layoutNotSet ||
+               localSizeSpecId[1] != TQualifier::layoutNotSet ||
+               localSizeSpecId[2] != TQualifier::layoutNotSet;
+    }
 #ifdef GLSLANG_WEB
     void output(TInfoSink&, bool tree) { }