[Mesa-dev] [PATCH 01/11] mesa: Returns a GL_INVALID_VALUE error on several glGet* APIs when max length is negative

[Erik Faye-Lund]

On Mon, Jan 19, 2015 at 1:31 PM, Erik Faye-Lund <kusmabite at gmail.com> wrote:
> On Mon, Jan 19, 2015 at 12:32 PM, Eduardo Lima Mitev <elima at igalia.com> wrote:
>> The manual page for glGetAttachedShaders, glGetShaderSource, glGetActiveUniform and
>> glGetActiveUniform state that a GL_INVALID_VALUE is returned if the maximum length
>> argument is less than zero. For reference, see:
>> https://www.opengl.org/sdk/docs/man3/xhtml/glGetAttachedShaders.xml,
>> https://www.khronos.org/opengles/sdk/docs/man31/html/glGetAttachedShaders.xhtml,
>> https://www.opengl.org/sdk/docs/man3/xhtml/glGetShaderSource.xml,
>> https://www.khronos.org/opengles/sdk/docs/man31/html/glGetShaderSource.xhtml,
>> https://www.opengl.org/sdk/docs/man3/xhtml/glGetActiveUniform.xml,
>> https://www.khronos.org/opengles/sdk/docs/man31/html/glGetActiveUniform.xhtml,
>> https://www.opengl.org/sdk/docs/man3/xhtml/glGetActiveAttrib.xml,
>> https://www.khronos.org/opengles/sdk/docs/man31/html/glGetActiveAttrib.xhtml.
>>
>> This fixes 4 dEQP test:
>> * dEQP-GLES3.functional.negative_api.state.get_attached_shaders
>> * dEQP-GLES3.functional.negative_api.state.get_shader_source
>> * dEQP-GLES3.functional.negative_api.state.get_active_uniform
>> * dEQP-GLES3.functional.negative_api.state.get_active_attrib
>
> These tests are about GLES3, but I cannot find such behavior specified
> in the OpenGL ES 3.0 specification for GetAttachedShaders nor
> GetProgramBinary. I stopped checking after those two, because I felt I
> saw a pattern ;)
>
> The man pages you linked to are for desktop-OpenGL, which *does*
> specify such an error; OpenGL 4.5 spec says "An INVALID_VALUE error is
> generated if maxCount is negative" about GetAttachedShaders (and a
> similar for GetProgramBinary()).
>
> However, the GLES 3 man pages also list such an error:
> https://www.khronos.org/opengles/sdk/docs/man3/html/glGetAttachedShaders.xhtml
>
> Generally speaking, the manual pages are not considered to dictate
> behavior, only to be a programmer convenience. And they have
> historically been full of errors. However, since desktop GL *does*
> specify these errors *and* the man-pages document them, this does look
> like a spec-error for GLES 3 to me. But I think we should get a
> clarification from Khronos before assuming so, otherwise we won't be
> in conformance. Ian, any thoughts?

By the way, this error is also properly defined for OpenGL ES 3.1, so
I'm feeling even more confident that it's a spec-bug in OpenGL ES 3.0.