Invalid optimization of reduce expression with undef bits

OPEN: last verified in Quartus 17.0

Consider the following test case:

module issue_042(y);
  output [3:0] y;
  localparam [3:0] p11 = 1'bx;
  assign y = ~&p11;

Quartus 15.0 sets y to constant 4'b0000. The correct value for y would be 4'b0001.

Crosscheck: Vivado 2015.1, XSim 2015.1, Modelsim 10.3d, Icarus Verilog (git 02ee387), and Verilator (git e5af46d) all agree on the correct behavior.

2015-05-15 Reported via Altera mySupport (SR #11146970)
2017-07-01 Still broken in Quartus II 17.0

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