Disallow redefinition of built-in functions.

src/compiler/SymbolTable.h

@@ -298,6 +298,11 @@ public:
         return symbol;
     }
 
+    TSymbol *findBuiltIn(const TString &name)
+    {
+        return table[0]->find(name);
+    }
+
     TSymbolTableLevel* getGlobalLevel() {
         assert(table.size() >= 2);
         return table[1];

src/compiler/glslang.y

@@ -2034,6 +2034,15 @@ external_declaration
 function_definition
     : function_prototype {
         TFunction* function = $1.function;
+        
+        const TSymbol *builtIn = context->symbolTable.findBuiltIn(function->getMangledName());
+        
+        if (builtIn)
+        {
+            context->error($1.line, "built-in functions cannot be redefined", function->getName().c_str());
+            context->recover();
+        }
+        
         TFunction* prevDec = static_cast<TFunction*>(context->symbolTable.find(function->getMangledName()));
         //
         // Note:  'prevDec' could be 'function' if this is the first time we've seen function

src/compiler/glslang_tab.cpp

@@ -4428,6 +4428,15 @@ yyreduce:
 
     {
         TFunction* function = (yyvsp[(1) - (1)].interm).function;
+        
+        const TSymbol *builtIn = context->symbolTable.findBuiltIn(function->getMangledName());
+        
+        if (builtIn)
+        {
+            context->error((yyvsp[(1) - (1)].interm).line, "built-in functions cannot be redefined", function->getName().c_str());
+            context->recover();
+        }
+        
         TFunction* prevDec = static_cast<TFunction*>(context->symbolTable.find(function->getMangledName()));
         //
         // Note:  'prevDec' could be 'function' if this is the first time we've seen function