Further improvements to error reporting with function types.

Issue #219.

expr.cpp

@@ -328,8 +328,8 @@ lDoTypeConv(const Type *fromType, const Type *toType, Expr **expr,
                  !Type::Equal(fromPointerType->GetBaseType()->GetAsConstType(), 
                               toPointerType->GetBaseType())) {
             if (!failureOk)
-                Error(pos, "Can't convert between incompatible pointer types "
-                      "\"%s\" and \"%s\" for %s.",
+                Error(pos, "Can't convert from pointer type \"%s\" to "
+                      "incompatible pointer type \"%s\" for %s.",
                       fromPointerType->GetString().c_str(),
                       toPointerType->GetString().c_str(), errorMsgBase);
             return false;

tests_errors/ptr-1.ispc

@@ -1,4 +1,4 @@
-// Can't convert between incompatible pointer types
+// Can't convert from pointer type "void * varying" to incompatible pointer type "uniform int32 * varying" for return statement
 
 int *foo(void *p) {
     return p;

type.cpp

@@ -2466,18 +2466,7 @@ FunctionType::GetAsNonConstType() const {
 
 std::string
 FunctionType::GetString() const {
-    std::string ret;
-    if (isTask) ret += "task ";
-    if (isSafe) ret += "/*safe*/ ";
-    if (costOverride > 0) {
-        char buf[32];
-        sprintf(buf, "/*cost=%d*/ ", costOverride);
-        ret += buf;
-    }
-    if (returnType != NULL)
-        ret += returnType->GetString();
-    else
-        ret += "/* ERROR */";
+    std::string ret = GetReturnTypeString();
     ret += "(";
     for (unsigned int i = 0; i < paramTypes.size(); ++i) {
         if (paramTypes[i] == NULL)
@@ -2554,6 +2543,9 @@ FunctionType::GetDIType(llvm::DIDescriptor scope) const {
 
 const std::string
 FunctionType::GetReturnTypeString() const {
+    if (returnType == NULL)
+        return "/* ERROR */";
+
     std::string ret;
     if (isTask)
         ret += "task ";
@@ -2561,6 +2553,13 @@ FunctionType::GetReturnTypeString() const {
         ret += "export ";
     if (isExternC)
         ret += "extern \"C\" ";
+    if (isSafe) 
+        ret += "/*safe*/ ";
+    if (costOverride > 0) {
+        char buf[32];
+        sprintf(buf, "/*cost=%d*/ ", costOverride);
+        ret += buf;
+    }
     return ret + returnType->GetString();
 }