GLSL spec 5.4.2 says about vector constructor:
It is an error to provide extra arguments beyond this last used argument.

But mesa passes for:
    vec3 v;
    vec4 v1 = vec4(v,v,v);
or
    int i;
    vec4 v1 = vec4(i,i,i,i,i);

This impacts tests/glslparsertest/shaders/constructor3.V110.frag (though I don't understand why it uses "V110" -- the is defined through V110 to V150)