Fix several bugs with `specializeWithArgTypes()` (#5365)

* Fix several bugs with `specializeWithArgTypes()`

* Make all types L-values for the purposes of reflection API resolution

1 files changed, 9 insertions, 4 deletions

diff --git a/source/slang/slang-reflection-api.cpp b/source/slang/slang-reflection-api.cpp
index 45bbd400c..ae351aee9 100644
--- a/source/slang/slang-reflection-api.cpp
+++ b/source/slang/slang-reflection-api.cpp
@@ -808,9 +808,9 @@ SlangReflectionFunction* tryConvertExprToFunctionReflection(ASTBuilder* astBuild
         auto declRef = declRefExpr->declRef;
         if (auto genericDeclRef = declRef.as<GenericDecl>())
         {
-            auto innerDeclRef = substituteDeclRef(
-                SubstitutionSet(genericDeclRef), astBuilder, genericDeclRef.getDecl()->inner);
-            declRef = createDefaultSubstitutionsIfNeeded(astBuilder, nullptr, innerDeclRef);
+            auto innerDeclRef = createDefaultSubstitutionsIfNeeded(astBuilder, nullptr, genericDeclRef.getDecl()->inner);
+            declRef = substituteDeclRef(
+                SubstitutionSet(genericDeclRef), astBuilder, innerDeclRef);
         }
 
         if (auto funcDeclRef = declRef.as<FunctionDeclBase>())
@@ -3194,7 +3194,12 @@ SLANG_API SlangReflectionFunction* spReflectionFunction_specializeWithArgTypes(
     try 
     {
         DiagnosticSink sink(linkage->getSourceManager(), Lexer::sourceLocationLexer);
-        return convert(linkage->specializeWithArgTypes(funcExpr, argTypeList, &sink).as<FunctionDeclBase>());
+        auto resultFunc = linkage->specializeWithArgTypes(funcExpr, argTypeList, &sink).as<FunctionDeclBase>();
+
+        if (sink.getErrorCount() != 0)
+            return nullptr; // Failed coercion.
+
+        return convert(resultFunc);
     }
     catch (...)
     {