From f4c4f63c0cfad93b1eacf9300eb8e06d2c78ccc9 Mon Sep 17 00:00:00 2001
From: Tim Foley <tfoley@nvidia.com>
Date: Tue, 7 Nov 2017 10:02:10 -0800
Subject: Fix for emitting subscript calls in HLSL/GLSL

The old approach was relying on an `__intrinsic_op` modifier to tell us we need to do something special with an `InvokeExpr`, but a previous change removed a bunch of those modifiers.

Instead, we will now check for calls to subscript declarations as part of the normal flow of emitting *any* call, similar to what is done for constructor calls already.

Eventually we should be able to eliminate the special case in the `__intrinsic_op` path, but I'm holding off on that because the AST emit logic can probably be cleaned up a *lot* once it doesn't have to be used for cross-compilation as well.
---
 source/slang/emit.cpp | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'source/slang/emit.cpp')

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 615fb47a0..c67bb7b29 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -1614,6 +1614,32 @@ struct EmitVisitor
         }
     }
 
+    void emitSimpleSubscriptCallExpr(
+        RefPtr<InvokeExpr>  callExpr,
+        EOpInfo             /*outerPrec*/)
+    {
+        auto funcExpr = callExpr->FunctionExpr;
+
+        // We expect any subscript operation to be invoked as a member,
+        // so the function expression had better be in the correct form.
+        auto memberExpr = funcExpr.As<MemberExpr>();
+        if(!memberExpr)
+        {
+            SLANG_UNEXPECTED("subscript needs base expression");
+        }
+
+        Emit("(");
+        EmitExpr(memberExpr->BaseExpression);
+        Emit(")[");
+        UInt argCount = callExpr->Arguments.Count();
+        for (UInt aa = 0; aa < argCount; ++aa)
+        {
+            if (aa != 0) Emit(", ");
+            EmitExpr(callExpr->Arguments[aa]);
+        }
+        Emit("]");
+    }
+
     // Emit a call expression that doesn't involve any special cases,
     // just an expression of the form `f(a0, a1, ...)`
     void emitSimpleCallExpr(
@@ -1632,6 +1658,18 @@ struct EmitVisitor
                 emitSimpleConstructorCallExpr(callExpr, outerPrec);
                 return;
             }
+
+            if(auto acessorDeclRef = declRef.As<AccessorDecl>())
+            {
+                declRef = acessorDeclRef.GetParent();
+            }
+
+            if(auto subscriptDeclRef = declRef.As<SubscriptDecl>())
+            {
+                emitSimpleSubscriptCallExpr(callExpr, outerPrec);
+                return;
+            }
+
         }
 
         // Once we've ruled out constructor calls, we can move on
-- 
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