[glsl-out] ImageMultipleSamplers error for multiple samplers due to name collision

[jakobhellermann]

Given the WGSL code

[[group(0), binding(1)]]
var texture_a: texture_2d<f32>;
[[group(0), binding(2)]]
var sampler_a: sampler;
[[group(0), binding(3)]]
var texture_b: texture_2d<f32>;
[[group(0), binding(4)]]
var sampler_b: sampler;

[[stage(fragment)]]
fn main() -> [[location(0)]] vec4<f32> {
    let a = textureSample(texture_a, sampler_a, vec2<f32>(0.0));
    let b = textureSample(texture_b, sampler_b, vec2<f32>(0.0));
    return vec4<f32>(1.0);
}

naga fails to convert it to GLSL due to Conflicting samplers for _group_0_binding_3.

The relevant code is here

naga/src/back/glsl/mod.rs

Lines 2441 to 2457 in 526a29e

	let global = self.module.global_variables[sampling.image].clone();
	let tex_name = self.reflection_names[&global.ty].clone();
	match mappings.entry(tex_name) {
	Entry::Vacant(v) => {
	v.insert(TextureMapping {
	texture: sampling.image,
	sampler: Some(sampling.sampler),
	});
	}
	Entry::Occupied(e) => {
	if e.get().sampler != Some(sampling.sampler) {
	log::error!("Conflicting samplers for {}", e.key());
	return Err(Error::ImageMultipleSamplers);
	}
	}
	}

Logging the global and tex_name values gives to

GlobalVariable { name: Some("texture_a"), class: Handle, binding: Some(ResourceBinding { group: 0, binding: 1 }), ty: [1], init: None, storage_access: (empty) }
_group_0_binding_3
GlobalVariable { name: Some("texture_b"), class: Handle, binding: Some(ResourceBinding { group: 0, binding: 3 }), ty: [1], init: None, storage_access: (empty) }
_group_0_binding_3

The tex_name is looked up using only the global's ty which is the same for both both textures.

[Gordon-F]

Hello @jakobhellermann! Thank you for reporting this. Would you like to send a PR with a fix?

[jakobhellermann]

I opened a PR: #1144