Test for non-causal detection.

test/feedback-noncausal.slang

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+#version 450
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+   mat4 MVP;
+   vec4 SourceSize;
+   vec4 PassOutputSize0;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 1) uniform sampler2D Source;
+
+// This should intentionally fail to validate in the frontend.
+layout(set = 0, binding = 2) uniform sampler2D PassOutput0;
+
+void main()
+{
+   vec2 tex = floor(global.PassOutputSize0.xy * vTexCoord);
+   tex = (tex + 0.5) * global.PassOutputSize0.zw;
+
+   vec3 current = texture(Source, tex).rgb;
+   vec3 prev = texture(PassOutput0, tex).rgb;
+   FragColor = vec4(mix(current, prev, 0.8), 1.0);
+}

test/feedback-noncausal.slangp

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+shaders = 1
+shader0 = feedback-noncausal.slang
+scale_type0 = source
+scale0 = 1.0
+filter_linear0 = false