I have run the i++ compilation on Ubuntu, and I get the following error: I am using Quartus® Prime Pro Edition ver. 18.1.

GCC 5.4.0 is the supported version for Quartus® Prime Pro Edition ver. 18.1. 
Please change to GCC 5.4.0 and try it.

Please refer to the following document for Altera® HLS Compiler support environment.

Altera High Level Synthesis Compiler: User Guide 
https://docs.altera.com/r/docs/683456/24.1/altera-high-level-synthesis-compiler-pro-edition-user-guide/discontinuation-of-the-intel-hls-compiler

(Search by Compiler support)

-------------------- 
Category: HLS 
Tools: Altera® HLS Compiler 
Device: Arria® 10