Feature/as refactor review (#821)

* Replace dynamicCast with as where does not change behavior (ie not Type derived).
Use free function where scoping is clear.

* Replace uses of dynamicCast with as when there is no difference in behavior.

* Remove the IsXXXX methods from Type.

* Don't have separate smart pointer to store canonicalType on Type.

* Simplify Slang.FilteredMemberRefList.Adjust, such does the cast directly.

* Use free as where appropriate.

* Use free function version of casts where appropriate.

* Fix text in casting.md

* Fix typos in decl-refs.md

* Remove the uses of free function as on RefDecl.
Add 'canAs' to RefDecl as a way to test if a cast is possible.
Moved 'as' into RefDeclBase.

* Use 'is' to test for as cast on smart pointers.
Fix small scope issue.

* * Cache stringType and enumTypeType on the Session
* Make DeclRefType::Create return a RefPtr
* Make casting of result use the *method* .as  (cos using free function would mean objects being wrongly destroyed)
* Make results from createInstance ref'd to avoid possible leaks.

* Fix typo in template parameter for is on RefPtr.

1 files changed, 4 insertions, 4 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 224fa3a28..3be6c59cd 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -4238,11 +4238,11 @@ struct EmitVisitor
         if(auto layoutDecoration = inst->findDecoration<IRLayoutDecoration>())
         {
             auto layout = layoutDecoration->getLayout();
-            if(auto varLayout = dynamicCast<VarLayout>(layout))
+            if(auto varLayout = as<VarLayout>(layout))
             {
                 emitIRSemantics(ctx, varLayout);
             }
-            else if (auto entryPointLayout = dynamicCast<EntryPointLayout>(layout))
+            else if (auto entryPointLayout = as<EntryPointLayout>(layout))
             {
                 if(auto resultLayout = entryPointLayout->resultLayout)
                 {
@@ -5159,7 +5159,7 @@ struct EmitVisitor
     {
         if( auto layoutDecoration = func->findDecoration<IRLayoutDecoration>() )
         {
-            return dynamicCast<EntryPointLayout>(layoutDecoration->getLayout());
+            return as<EntryPointLayout>(layoutDecoration->getLayout());
         }
         return nullptr;
     }
@@ -5168,7 +5168,7 @@ struct EmitVisitor
     {
         if (auto layoutDecoration = func->findDecoration<IRLayoutDecoration>())
         {
-            if (auto entryPointLayout = dynamicCast<EntryPointLayout>(layoutDecoration->getLayout()))
+            if (auto entryPointLayout = as<EntryPointLayout>(layoutDecoration->getLayout()))
             {
                 return entryPointLayout;
             }