Allow for automatic importing of Slang code

The basic idea of this change is that user code can just write:

    #include "foo.h"

and then if `foo.h` gets found in a list of registered directories for "auto-import," then it actually gets interpreted as if the user had writte, more or less:

    __import foo;

That is, the code in `foo.h` will be treated as Slang, and will be fully parsed and checked (no matter what the source language had been), and the scoping rules will be those of `__import` instead of `#include`.

This is a really big hammer, and I could imagine it smashing fingers if used poorly.
I'm not sure this feature will pan out, but we need to try things to know.

One big piece of that that I'll likely keep in either case is an overhaul of command-line options parsing for `slangc`. In particular, this logic has been moved into the core `slang` library (so that users can just pass options in via the API), and it is all done on UTF-8 strings rather than wide strings (which was always going to be Windows-specific).

2 files changed, 168 insertions, 0 deletions

diff --git a/tests/render/auto-import.hlsl b/tests/render/auto-import.hlsl
new file mode 100644
index 000000000..588ebc612
--- /dev/null
+++ b/tests/render/auto-import.hlsl
@@ -0,0 +1,147 @@
+//TEST(smoke,render):COMPARE_HLSL_GLSL_RENDER: -xslang -auto-import-dir -xslang tests/render/
+
+// This is a basic test case for cross-compilation behavior.
+//
+// We will define distinct HLSL and GLSL entry points,
+// but the two will share a dependency on a file of
+// pure Spire code that provides the actual shading logic.
+
+
+// Pull in Spire code depdendency using extended syntax:
+#include "auto-import.slang.h"
+
+#if defined(__HLSL__)
+
+cbuffer Uniforms
+{
+	float4x4 modelViewProjection;
+};
+
+struct AssembledVertex
+{
+	float3	position;
+	float3	color;
+};
+
+struct CoarseVertex
+{
+	float3	color;
+};
+
+struct Fragment
+{
+	float4 color;
+};
+
+// Vertex  Shader
+
+struct VertexStageInput
+{
+	AssembledVertex assembledVertex	: A;
+};
+
+struct VertexStageOutput
+{
+	CoarseVertex	coarseVertex	: CoarseVertex;
+	float4			sv_position		: SV_Position;
+};
+
+VertexStageOutput vertexMain(VertexStageInput input)
+{
+	VertexStageOutput output;
+
+	float3 position = input.assembledVertex.position;
+	float3 color	= input.assembledVertex.color;
+
+	output.coarseVertex.color = color;
+	output.sv_position = mul(modelViewProjection, float4(position, 1.0));
+
+	return output;
+	
+}
+
+// Fragment Shader
+
+struct FragmentStageInput
+{
+	CoarseVertex	coarseVertex	: CoarseVertex;
+};
+
+struct FragmentStageOutput
+{
+	Fragment fragment	: SV_Target;
+};
+
+FragmentStageOutput fragmentMain(FragmentStageInput input)
+{
+	FragmentStageOutput output;
+
+	float3 color = input.coarseVertex.color;
+
+	color = transformColor(color);
+
+	output.fragment.color = float4(color, 1.0);
+
+	return output;
+}
+
+#elif defined(__GLSL__)
+
+#version 420
+
+uniform Uniforms
+{
+	mat4x4 modelViewProjection;
+};
+
+#define ASSEMBLED_VERTEX(QUAL)		\
+	/* */
+
+#define V2F(QUAL)			\
+	QUAL vec3 coarse_color;	\
+	/* */
+
+// Vertex  Shader
+
+#ifdef __GLSL_VERTEX__
+
+layout(location = 0)
+in vec3 assembled_position;
+
+layout(location = 1)
+in vec3 assembled_color;
+
+V2F(out)
+
+void main()
+{
+	vec3 position = assembled_position;
+	vec3 color	= assembled_color;
+
+	coarse_color = color;
+//	gl_Position = modelViewProjection * vec4(position, 1.0);
+	gl_Position = vec4(position, 1.0) * modelViewProjection;
+}
+
+#endif
+
+#ifdef __GLSL_FRAGMENT__
+
+V2F(in)
+
+layout(location = 0)
+out vec4 fragment_color;
+
+void main()
+{
+	vec3 color = coarse_color;
+
+	color = transformColor(color);
+
+	fragment_color = vec4(color, 1.0);
+}
+
+
+#endif
+
+#endif
diff --git a/tests/render/auto-import.slang.h b/tests/render/auto-import.slang.h
new file mode 100644
index 000000000..d53005688
--- /dev/null
+++ b/tests/render/auto-import.slang.h
@@ -0,0 +1,21 @@
+//TEST_IGNORE_FILE:
+
+// This file implements the "library" code
+// that both the HLSL and GLSL shaders share.
+//
+// This code is written in Slang (more or less
+// just HLSL), and will be translated as needed
+// for each of the targets.
+
+float3 transformColor(float3 color)
+{
+	float3 result;
+
+	result.x = sin(20.0 * (color.x + color.y));
+	result.y = saturate(cos(color.z * 30.0));
+	result.z = sin(color.x * color.y * color.z * 100.0);
+
+	result = 0.5 * (result + 1);
+
+	return result;
+}
\ No newline at end of file