SystemVerilog function prototypes (pure virtual functions) should have a return type. SVH warns for function prototypes without return type (rule 10).
virtual class badclass;
pure virtual function myfunc(input bit[31:0] data); // return type missing
endclass
virtual class goodclass;
pure virtual function integer myfunc(input bit[31:0] data);
endclass
Rule Configuration
These rules can be disabled for your project, or their severity and parameters can be modified in the project linting settings. Alternatively, they can be manually configured with the following template:
10/severity/${path}={error|warning|info|ignore} # Function prototype with implicit return type