Setting gl_FragDepth in fragment shader causes Err

[wddl]

Setting gl_FragDepth in fragment shader. this is wrong in wasm mode. Chrome prompt:
render_ gl.cpp (6490): BGFX 0x00000001: Failed to compile shader. 0: ERROR: 0:7: 'gl_' : reserved built-in name。

The shader code is as follows:

gl_ FragDepth = log2(flogz) * Fcoef_ half;

can you help me? thanks

[pezcode]

You have a space between gl_ and FragDepth