Pick correct GLSL version when `gl_Layer` used

`gl_Layer` as a fragment input requires at least version 4.30 of GLSL, so we try to track that information when we see the name used.

Note that this does *not* override a user-specified `#version` line.

This required re-ordering when lowering happens relative to emitting the `#version` directive, since this code works by actually modifying the chosen profile for the entry point.
Yes, that is kind of gross and we should do something cleaner in the long term.

2 files changed, 36 insertions, 0 deletions

diff --git a/tests/cross-compile/gl-layer-pick-version.slang b/tests/cross-compile/gl-layer-pick-version.slang
new file mode 100644
index 000000000..c68d68427
--- /dev/null
+++ b/tests/cross-compile/gl-layer-pick-version.slang
@@ -0,0 +1,11 @@
+//TEST:CROSS_COMPILE: -profile ps_5_0 -entry main -target spirv-assembly
+
+struct VS_OUT
+{
+	nointerpolation uint layerID : SV_RenderTargetArrayIndex;	
+};
+
+float4 main(VS_OUT vsOut) : SV_Target
+{
+	return float4(float(vsOut.layerID));
+}
diff --git a/tests/cross-compile/gl-layer-pick-version.slang.glsl b/tests/cross-compile/gl-layer-pick-version.slang.glsl
new file mode 100644
index 000000000..55d419405
--- /dev/null
+++ b/tests/cross-compile/gl-layer-pick-version.slang.glsl
@@ -0,0 +1,25 @@
+//TEST_IGNORE_FILE:
+#version 430
+
+struct VS_OUT
+{
+	uint layerID;
+};
+
+vec4 main_(VS_OUT vsOut) : SV_Target
+{
+	return vec4(float(vsOut.layerID));
+}
+
+out vec4 SLANG_out_main_result;
+
+void main()
+{
+	VS_OUT vsOut;
+	vsOut.layerID = gl_Layer;
+
+	vec4 main_result;
+	main_result = main_(vsOut);
+
+	SLANG_out_main_result = main_result;
+}
\ No newline at end of file