From bee74b16eafa64ccc33bb386a1dc753cd6c41a82 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Thu, 26 Oct 2023 14:01:26 -0700
Subject: Add more diagnostics around use of custom derivatives. (#3291)

Co-authored-by: Yong He <yhe@nvidia.com>
---
 source/slang/slang-check-decl.cpp | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

(limited to 'source/slang/slang-check-decl.cpp')

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index f75f84e21..15831ba26 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -7203,10 +7203,17 @@ namespace Slang
     template<typename TDerivativeAttr>
     void checkDerivativeAttributeImpl(
         SemanticsVisitor* visitor,
+        Decl* funcDecl,
         TDerivativeAttr* attr,
         const List<Expr*>& imaginaryArguments,
         const List<ParameterDirection>& expectedParamDirections)
     {
+        if (isInterfaceRequirement(funcDecl))
+        {
+            visitor->getSink()->diagnose(attr, Diagnostics::cannotAssociateInterfaceRequirementWithDerivative);
+            return;
+        }
+
         SemanticsContext::ExprLocalScope scope;
         auto ctx = visitor->withExprLocalScope(&scope);
         auto subVisitor = SemanticsVisitor(ctx);
@@ -7264,6 +7271,20 @@ namespace Slang
                 // We'll detect both these incorrect cases here and issue an appropriate diagnostic.
                 // 
                 auto funcType = as<FuncType>(calleeDeclRef->type);
+                if (!funcType)
+                {
+                    // The best candidate does not have a function type.
+                    // If we reach here, it means the function is a generic and we can't deduce the
+                    // generic arguments from imaginary argument list.
+                    // In this case we issue a diagnostic to ask the user to explicitly provide the arguments.
+                    visitor->getSink()->diagnose(attr, Diagnostics::cannotResolveGenericArgumentForDerivativeFunction);
+                    return;
+                }
+                if (isInterfaceRequirement(calleeDeclRef->declRef.getDecl()))
+                {
+                    visitor->getSink()->diagnose(attr, Diagnostics::cannotUseInterfaceRequirementAsDerivative);
+                    return;
+                }
                 for (Index ii = 0; ii < imaginaryArguments.getCount(); ++ii)
                 {
                     // Check if the resolved invoke argument type is an error type.
@@ -7511,6 +7532,16 @@ namespace Slang
             visitor->getSink()->diagnose(derivativeOfAttr, Diagnostics::cannotResolveOriginalFunctionForDerivative);
             return;
         }
+        if (isInterfaceRequirement(calleeFunc))
+        {
+            visitor->getSink()->diagnose(derivativeOfAttr, Diagnostics::cannotAssociateInterfaceRequirementWithDerivative);
+            return;
+        }
+        if (isInterfaceRequirement(funcDecl))
+        {
+            visitor->getSink()->diagnose(derivativeOfAttr, Diagnostics::cannotUseInterfaceRequirementAsDerivative);
+            return;
+        }
 
         if (auto existingModifier = _findModifier<TDerivativeAttr>(calleeFunc))
         {
@@ -7546,7 +7577,7 @@ namespace Slang
             return;
 
         ArgsWithDirectionInfo imaginaryArguments = getImaginaryArgsToForwardDerivative(visitor, funcDecl, attr->loc);
-        checkDerivativeAttributeImpl(visitor, attr, imaginaryArguments.args, imaginaryArguments.directions);
+        checkDerivativeAttributeImpl(visitor, funcDecl, attr, imaginaryArguments.args, imaginaryArguments.directions);
     }
 
     static void checkDerivativeAttribute(SemanticsVisitor* visitor, FunctionDeclBase* funcDecl, BackwardDerivativeAttribute* attr)
@@ -7557,7 +7588,7 @@ namespace Slang
             return;
 
         ArgsWithDirectionInfo imaginaryArguments = getImaginaryArgsToBackwardDerivative(visitor, funcDecl, attr->loc);
-        checkDerivativeAttributeImpl(visitor, attr, imaginaryArguments.args, imaginaryArguments.directions);
+        checkDerivativeAttributeImpl(visitor, funcDecl, attr, imaginaryArguments.args, imaginaryArguments.directions);
     }
 
     static void checkDerivativeAttribute(SemanticsVisitor* visitor, FunctionDeclBase* funcDecl, PrimalSubstituteAttribute* attr)
@@ -7568,7 +7599,7 @@ namespace Slang
             return;
 
         ArgsWithDirectionInfo imaginaryArguments = getImaginaryArgsToFunc(visitor->getASTBuilder(), funcDecl, attr->loc);
-        checkDerivativeAttributeImpl(visitor, attr, imaginaryArguments.args, imaginaryArguments.directions);
+        checkDerivativeAttributeImpl(visitor, funcDecl, attr, imaginaryArguments.args, imaginaryArguments.directions);
     }
 
     template<typename TDerivativeAttr, typename TDerivativeOfAttr>
-- 
cgit v1.2.3