We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 23475

XST - "FATAL_ERROR:HDLParsers:vhptype.c:174:$Id: vhptype.c"


When I use ALIAS in my HDL code without a subtype or create a record definition that has a parameter, the following fatal error occurs in XST: 

1) alias SIGN is REAL_NUMBER (0); 
2) type complex_t is record
re : signed((DATA_WIDTH -1) downto 0);
end record complex_t


FATAL_ERROR:HDLParsers:vhptype.c:174:$Id: vhptype.c


Solution 1:
The syntax for the ALIAS declaration is as follows:

alias alias_designator [ : subtype_indication ] is name [ signature ] ; 

The absence of subtype for the alias_designator is not supported in XST.

Consequently, the alias should be declared as shown below:

alias SIGN :BIT is REAL_NUMBER (0) 

The alias construct is not fully supported in XST and the following alias constructs are not supported: 

  • An alias of an alias 
  • An alias declaration without subtype_indication 
  • Signatures on alias declarations 
  • An operator symbol as alias_designator  
  • An alias of an operator symbol  
  • Character literals as alias designators  
  • An alias to user-defined functions

Solution 2:
Use a hard coded value to define the data width instead or a parameter.


Solution 3:

In some cases this error has occurred when there is a corrupt ISE project.

To resolve this select "Project" menu -> "Cleanup Project Files" and re-run XST.


AR# 23475
Date Created 09/04/2007
Last Updated 12/03/2014
Status Active
Type General Article