The Intel® HLS compiler is not supported in Quartus® Prime Standard Edition v20.1.
As with the HLS compiler, DSP Builder, Intel FPGA SDK for OpenCL™, Intel FPGA RTE for OpenCL These tools are not supported by Quartus.
Support for these tools will be finalized in Quartus® Prime Standard Edition v19.1.
（Intel Quartus Prime Standard Edition: Version 20.1 Software and Device Support Release Notes
https://www.intel.com/content/www/us/en/programmable/documentation/hco1416836145555.html
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/rn/rn-qts-std-dev-support.pdf
(Changes to Software Behavior section)
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Category: HLS
Tools: Intel® HLS Compiler
Devices: -