Initial `dyn` keyword support & `-lang 2026` compiler option (#7172)

fixes: [#7143](https://github.com/shader-slang/slang/issues/7143)
fixes: [#7146](https://github.com/shader-slang/slang/issues/7146)

Goal of PR: 
 * This PR is part of the larger #7115 refactor to how dynamic dispatch works.
 * The first step is to add the `-std <std-revision>` flag.
 * The second step is to provide basic `dyn` keyword support in AST. This does not include `varDecl` support since most of these interactions require `some` keyword support.

Future PR(s) goal:
 * Support `some` keyword in AST. With this we will also implement all varDecl interactions between `dyn` and `some`.
 * Add IR support for `some` and `dyn`.

Breakdown of PR:
 * most of the logic is in `validateDyn.*`. This was done so that in the future when we implement more features we will have an easy time removing/adding restrictions to `dyn` interfaces.

Breaking changes:
* As per spec (https://github.com/shader-slang/spec/pull/14/files), any type conforming to a `dyn` interface errors if member list contains one of the following: opaque type, non copyable type, or unsized type.
* Due to the breaking change, the test `tests\compute\dynamic-dispatch-bindless-texture.slang` is incorrect. This has been fixed.

1 files changed, 14 insertions, 0 deletions

diff --git a/include/slang.h b/include/slang.h
index d65362762..4164ce9e9 100644
--- a/include/slang.h
+++ b/include/slang.h
@@ -627,6 +627,17 @@ typedef uint32_t SlangSizeT;
         SLANG_TARGET_COUNT_OF,
     };
 
+    typedef int SlangStdRevisionIntegral;
+    enum SlangStdRevision : SlangStdRevisionIntegral
+    {
+        SLANG_STD_REVISION_UNKNOWN,
+        SLANG_STD_REVISION_2025,
+        SLANG_STD_REVISION_2026,
+        SLANG_STD_REVISION_COUNT_OF,
+
+        SLANG_STD_REVISION_DEFAULT = SLANG_STD_REVISION_2025,
+    };
+
     /* A "container format" describes the way that the outputs
     for multiple files, entry points, targets, etc. should be
     combined into a single artifact for output. */
@@ -1021,6 +1032,9 @@ typedef uint32_t SlangSizeT;
 
         SkipDownstreamLinking, // bool, experimental
         DumpModule,
+
+        EnableExperimentalDynamicDispatch, // bool, experimental
+        StdRevision,                       // intValue0: SlangStdRevision
         CountOf,
     };