yosys/tests/various/constant_drive_conflict.ys

read_verilog <<EOT
module top(input A, output Y);
	assign A = 1;

	assign Y = A;
endmodule
EOT

hierarchy -top top; proc

logger -expect warning "Drivers conflicting with a constant" 1
logger -expect log "Found and reported 1 problems." 1
check
logger -check-expected

design -reset
read_verilog <<EOT
module top(input A, output Y);
	buffer some_buffer(A, Y);
	assign Y = 1;
endmodule
module buffer(input A, output Y);
	assign Y = A;
endmodule
EOT

hierarchy -top top; proc

logger -expect warning "Drivers conflicting with a constant" 1
logger -expect log "Found and reported 1 problems." 1
check
logger -check-expected

design -reset
read_verilog <<EOT
module top(input clk, input A, output Y);
	reg Q;
	always @(posedge clk) Q <= A;

	assign Q = 1;

	assign Y = A;
endmodule
EOT

hierarchy -top top

logger -expect warning "Drivers conflicting with a constant" 1
logger -expect log "Found and reported 1 problems." 1
check
logger -check-expected