Implement HLSL resource bindings and default type `float4` to `SubpassInput<T>` (#4462)

* Add case to `emitVectorReshape` for `vector<>` type, `scalar` value

1. Add new case
2. Add test

* fix warning

* fix warning

* Implement HLSL resource bindings and default type `float4` to `SubpassInput<T>`

fixes: #4440

1. Removed GLSLInputAttachmentIndexLayout modifier and the somewhat 'hacky' binding model 'Input Attachment' previously relied upon. This was changed to work with the slang-type-layout rules system. This change allows Slang automatic bindings, HLSL bindings, GLSL bindings, and translation of GLSL to and from HLSL bindings to work.
2. Added default argument `float4` to SubpassInput<T>.
3. Merged glsl.meta and hlsl.meta SubpassInput logic.

* fix InputAttachment attribute checks

fix InputAttachment attribute checks for HLSL and GLSL syntax

* remove unused var

* validate attribute correctly

Attributes do not have type information. We must check the type expression to validate attribute usage.

* remove hacky validation

type based validation before types are fully resolved is quite hacky and unstable to changes and wrapped types

* fix warning

* remove redundant `!= nullptr`

* remove extra `!= nullptr`

* fix some warnings/errors

* subpass capability to limit to dxc & remove default values in some functions

* revert logic to previous logic

revert logic to return if we have a binding regardless of if a VarDecl is given the binding

1 files changed, 13 insertions, 2 deletions

diff --git a/source/slang/slang-check-modifier.cpp b/source/slang/slang-check-modifier.cpp
index aa30f66ca..7721fedbf 100644
--- a/source/slang/slang-check-modifier.cpp
+++ b/source/slang/slang-check-modifier.cpp
@@ -474,6 +474,17 @@ namespace Slang
             }
             overloadRankAttr->rank = int32_t(rank->getValue());
         }
+        else if (auto inputAttachmentIndexLayoutAttribute = as<GLSLInputAttachmentIndexLayoutAttribute>(attr))
+        {
+            if (attr->args.getCount() != 1)
+                return false;
+    
+            auto location = checkConstantIntVal(attr->args[0]);
+            if(!location)
+                return false;
+
+            inputAttachmentIndexLayoutAttribute->location = location->getValue();
+        }
         else if (auto bindingAttr = as<GLSLBindingAttribute>(attr))
         {
             // This must be vk::binding or gl::binding (as specified in core.meta.slang under vk_binding/gl_binding)
@@ -1105,7 +1116,7 @@ namespace Slang
         case ASTNodeType::GLSLParsedLayoutModifier:
         case ASTNodeType::GLSLConstantIDLayoutModifier:
         case ASTNodeType::GLSLLocationLayoutModifier:
-        case ASTNodeType::GLSLInputAttachmentIndexLayoutModifier:
+        case ASTNodeType::GLSLInputAttachmentIndexLayoutAttribute:
         case ASTNodeType::GLSLOffsetLayoutAttribute:
         case ASTNodeType::GLSLUnparsedLayoutModifier:
         case ASTNodeType::GLSLLayoutModifierGroupMarker:
@@ -1185,7 +1196,7 @@ namespace Slang
         case ASTNodeType::GLSLParsedLayoutModifier:
         case ASTNodeType::GLSLConstantIDLayoutModifier:
         case ASTNodeType::GLSLLocationLayoutModifier:
-        case ASTNodeType::GLSLInputAttachmentIndexLayoutModifier:
+        case ASTNodeType::GLSLInputAttachmentIndexLayoutAttribute:
         case ASTNodeType::GLSLOffsetLayoutAttribute:
         case ASTNodeType::GLSLUnparsedLayoutModifier:
         case ASTNodeType::GLSLLayoutModifierGroupMarker: