Bitstring contains non-std_logic metavalue

VHDL bit strings include a base specifier followed by a string value. The characters allowed in the value depend on the base specifier, with only a specific set permitted. This linting rule detects string literals that are incorrectly defined. The example below shows an incorrect value, the decimal bit string can only contain numerical characters.

entity alu is
    port (
        op     : in  std_logic_vector(3 downto 0) := D"1_1";
        A, B   : in  std_logic_vector(3 downto 0);
        result : out std_logic_vector(3 downto 0)
    );
end alu;

Rule Configuration

This rule can be disabled for your project, or its severity and parameters can be modified in the project linting settings. Alternatively, it can be manually configured with the following template:

57/severity/${path}={error|warning|info|ignore}