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, 14 insertions, 2 deletions

diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index 3d9f1c199..e6913c6c0 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -8061,7 +8061,7 @@ namespace Slang
         GLSLLayoutLocalSizeAttribute* numThreadsAttrib = nullptr;
         GLSLLayoutDerivativeGroupQuadAttribute* derivativeGroupQuadAttrib = nullptr;
         GLSLLayoutDerivativeGroupLinearAttribute* derivativeGroupLinearAttrib = nullptr; 
-
+        GLSLInputAttachmentIndexLayoutAttribute* inputAttachmentIndexLayoutAttribute = nullptr;
         ImageFormat format;
 
         listBuilder.add(parser->astBuilder->create<GLSLLayoutModifierGroupBegin>());
@@ -8115,6 +8115,17 @@ namespace Slang
             {
                 derivativeGroupLinearAttrib = parser->astBuilder->create<GLSLLayoutDerivativeGroupLinearAttribute>();
             }
+            else if (nameText == "input_attachment_index")
+            {
+                inputAttachmentIndexLayoutAttribute = parser->astBuilder->create<GLSLInputAttachmentIndexLayoutAttribute>();
+                if (AdvanceIf(parser, TokenType::OpAssign))
+                {
+                    auto token = parser->ReadToken(TokenType::IntegerLiteral);
+                    auto intVal = getIntegerLiteralValue(token);
+                    inputAttachmentIndexLayoutAttribute->location = intVal;
+                }
+
+            }
             else if (nameText == "binding" ||
                 nameText == "set")
             {
@@ -8165,7 +8176,6 @@ namespace Slang
                 CASE(scalar, GLSLScalarModifier)
                 CASE(offset, GLSLOffsetLayoutAttribute)
                 CASE(location, GLSLLocationLayoutModifier) 
-                CASE(input_attachment_index, GLSLInputAttachmentIndexLayoutModifier)
                 {
                     modifier = parser->astBuilder->create<GLSLUnparsedLayoutModifier>();
                 }
@@ -8227,6 +8237,8 @@ namespace Slang
             listBuilder.add(derivativeGroupQuadAttrib);
         if(derivativeGroupLinearAttrib)
             listBuilder.add(derivativeGroupLinearAttrib);
+        if(inputAttachmentIndexLayoutAttribute)
+            listBuilder.add(inputAttachmentIndexLayoutAttribute);
 
         listBuilder.add(parser->astBuilder->create<GLSLLayoutModifierGroupEnd>());