Fix return type evaluation for embedded C functions

previously it was forced to ASTNodeDataType::double_t

src/language/ASTNodeDataTypeBuilder.cpp

@@ -4,6 +4,8 @@
 #include <PugsAssert.hpp>
 #include <SymbolTable.hpp>
 
+#include <CFunctionEmbedder.hpp>
+
 void
 ASTNodeDataTypeBuilder::_buildNodeDataTypes(ASTNode& n)
 {
@@ -254,9 +256,17 @@ ASTNodeDataTypeBuilder::_buildNodeDataTypes(ASTNode& n)
 
         n.m_data_type = data_type;
       } else if (n.children[0]->m_data_type == ASTNodeDataType::c_function_t) {
-        std::cout << __FILE__ << ':' << __LINE__ << ": " << rang::fgB::red << "datatype is incorrectly defined!"
-                  << rang::style::reset << '\n';
-        n.m_data_type = ASTNodeDataType::double_t;
+        const std::string c_function_name = n.children[0]->string();
+        auto& symbol_table                = *n.m_symbol_table;
+
+        auto [i_symbol, success] = symbol_table.find(c_function_name, n.begin());
+        Assert(success);
+
+        uint64_t c_function_id   = std::get<uint64_t>(i_symbol->attributes().value());
+        auto c_function_embedder = symbol_table.cFunctionEbedderTable()[c_function_id];
+        Assert(c_function_embedder);
+
+        n.m_data_type = c_function_embedder->getReturnDataType();
       } else {
         std::ostringstream message;
         message << "invalid function call\n"