Fix parsing GLSL SSBO arrays / bindless descriptors (#5932)

* Fix parsing GLSL SSBO arrays / bindless descriptors

* Clean up SSBO array parsing

* Fix mutable SSBO arrays not being detected as such

* Allow sized SSBO arrays

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>

2 files changed, 17 insertions, 2 deletions

diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index 1f2776ba0..7972e2d81 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -312,12 +312,17 @@ static bool isMutableGLSLBufferBlockVarExpr(Expr* expr)
     const auto derefExpr = as<DerefExpr>(expr);
     if (!derefExpr)
         return false;
-    const auto varExpr = as<VarExpr>(derefExpr->base);
+
+    // For SSBO arrays, derefExpr is expected to be IndexExpr instead of VarExpr
+    const auto indexExpr = as<IndexExpr>(derefExpr->base);
+
+    const auto varExpr =
+        indexExpr ? as<VarExpr>(indexExpr->baseExpression) : as<VarExpr>(derefExpr->base);
     // Check the declaration type
     if (!varExpr)
         return false;
 
-    const auto varExprType = varExpr->type->getCanonicalType();
+    const auto varExprType = (indexExpr ? indexExpr->type : varExpr->type)->getCanonicalType();
     const auto ssbt = as<GLSLShaderStorageBufferType>(varExprType);
     if (!ssbt)
         return false;
diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index 8a4ba55eb..1aa313fa8 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -3360,6 +3360,16 @@ static Decl* ParseBufferBlockDecl(
         reflectionNameModifier->nameAndLoc = bufferVarDecl->nameAndLoc;
         parser->ReadToken(TokenType::Semicolon);
     }
+    else if (
+        parser->options.allowGLSLInput && parser->LookAheadToken(TokenType::Identifier) &&
+        parser->LookAheadToken(TokenType::LBracket, 1))
+    {
+        // GLSL bindless buffers are denoted with [] after the name.
+        bufferVarDecl->nameAndLoc = ParseDeclName(parser);
+        bufferVarDecl->type.exp = parseBracketTypeSuffix(parser, bufferVarDecl->type.exp);
+        reflectionNameModifier->nameAndLoc = bufferVarDecl->nameAndLoc;
+        parser->ReadToken(TokenType::Semicolon);
+    }
     else
     {
         // Otherwise, we need to generate a name for the buffer variable.