A copy and paste error.
ivec2 textureSize(isampler1DArray sampler, int lod);
ivec2 textureSize(usampler1DArray sampler, int lod);
ivec3 textureSize( sampler2DArray sampler, int lod);
-ivec2 textureSize(isampler2DArray sampler, int lod);
-ivec2 textureSize(usampler2DArray sampler, int lod);
+ivec3 textureSize(isampler2DArray sampler, int lod);
+ivec3 textureSize(usampler2DArray sampler, int lod);
ivec2 textureSize(sampler1DArrayShadow sampler, int lod);
ivec3 textureSize(sampler2DArrayShadow sampler, int lod);
ivec2 textureSize(isampler1DArray sampler, int lod);
ivec2 textureSize(usampler1DArray sampler, int lod);
ivec3 textureSize( sampler2DArray sampler, int lod);
-ivec2 textureSize(isampler2DArray sampler, int lod);
-ivec2 textureSize(usampler2DArray sampler, int lod);
+ivec3 textureSize(isampler2DArray sampler, int lod);
+ivec3 textureSize(usampler2DArray sampler, int lod);
ivec2 textureSize(sampler1DArrayShadow sampler, int lod);
ivec3 textureSize(sampler2DArrayShadow sampler, int lod);