fix all unreachable code warnings

11 files changed, 52 insertions, 43 deletions

diff --git a/source/core/common.h b/source/core/common.h
index dbb837821..3a4543085 100644
--- a/source/core/common.h
+++ b/source/core/common.h
@@ -43,6 +43,14 @@ namespace Slang
 #define SLANG_RETURN_NEVER /* empty */
 #endif
 
+#ifdef _MSC_VER
+#define UNREACHABLE_RETURN(x)
+#define UNREACHABLE(x)
+#else
+#define UNREACHABLE_RETURN(x) return x;
+#define UNREACHABLE(x) x;
+#endif
+
     SLANG_RETURN_NEVER void signalUnexpectedError(char const* message);
 }
 
diff --git a/source/slang/bytecode.cpp b/source/slang/bytecode.cpp
index f1b23849d..ed969b72d 100644
--- a/source/slang/bytecode.cpp
+++ b/source/slang/bytecode.cpp
@@ -271,9 +271,9 @@ BCConst getGlobalValue(
     }
 
     SLANG_UNEXPECTED("no ID for inst");
-    bcConst.flavor = (BCConstFlavor) -1;
-    bcConst.id = -9999;
-    return bcConst;
+    UNREACHABLE(bcConst.flavor = (BCConstFlavor) -1);
+    UNREACHABLE(bcConst.id = -9999);
+    UNREACHABLE_RETURN(bcConst);
 }
 
 Int getLocalID(
@@ -577,7 +577,7 @@ BytecodeGenerationPtr<BCType> emitBCTypeImpl(
 
 
     SLANG_UNEXPECTED("unimplemented");
-    return BytecodeGenerationPtr<BCType>();
+    UNREACHABLE_RETURN(BytecodeGenerationPtr<BCType>());
 }
 
 BytecodeGenerationPtr<BCType> emitBCType(
diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index 0c35c4bf4..dbbd8f283 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -3328,7 +3328,7 @@ namespace Slang
                 // to `interfaceDeclRef`.
                 //
                 SLANG_UNEXPECTED("reflexive type witness");
-                return nullptr;
+                UNREACHABLE_RETURN(nullptr);
             }
 
             auto breadcrumbs = inBreadcrumbs;
@@ -3343,7 +3343,7 @@ namespace Slang
                 // because `A : B` and `B : C` then `A : C`
                 //
                 SLANG_UNEXPECTED("transitive type witness");
-                return nullptr;
+                UNREACHABLE_RETURN(nullptr);
             }
 
             // Simple case: we have a single declaration
@@ -5947,7 +5947,7 @@ namespace Slang
         RefPtr<Expr> visitStaticMemberExpr(StaticMemberExpr* expr)
         {
             SLANG_UNEXPECTED("should not occur in unchecked AST");
-            return expr;
+            UNREACHABLE_RETURN(expr);
         }
 
         RefPtr<Expr> lookupResultFailure(
diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 2e8ab58d4..af4f0ad6a 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -4667,7 +4667,7 @@ emitDeclImpl(decl, nullptr);
             if(!isDigit(c))
             {
                 SLANG_UNEXPECTED("bad name mangling");
-                return 0;
+                UNREACHABLE_RETURN(0);
             }
             get();
 
@@ -4700,7 +4700,7 @@ emitDeclImpl(decl, nullptr);
                 if(count > (end_ - cursor_))
                 {
                     SLANG_UNEXPECTED("bad name mangling");
-                    return result;
+                    UNREACHABLE_RETURN(result);
                 }
 
                 result = UnownedStringSlice(cursor_, cursor_ + count);
diff --git a/source/slang/ir.cpp b/source/slang/ir.cpp
index 5cc73a36b..102fb947c 100644
--- a/source/slang/ir.cpp
+++ b/source/slang/ir.cpp
@@ -2540,7 +2540,7 @@ namespace Slang
 
         default:
             SLANG_UNEXPECTED("unimplemented");
-            return ScalarizedVal();
+            UNREACHABLE_RETURN(ScalarizedVal());
         }
 
     }
@@ -3064,7 +3064,7 @@ namespace Slang
 
         default:
             SLANG_UNEXPECTED("no value registered for IR value");
-            return nullptr;
+            UNREACHABLE_RETURN(nullptr);
         }
     }
 
@@ -3401,7 +3401,7 @@ namespace Slang
 
         default:
             SLANG_UNEXPECTED("unhandled case");
-            return "unknown";
+            UNREACHABLE_RETURN("unknown");
         }
     }
 
@@ -3503,7 +3503,7 @@ namespace Slang
         {
             // This shouldn't happen!
             SLANG_UNEXPECTED("no matching function registered");
-            return cloneSimpleFunc(context, originalFunc);
+            UNREACHABLE_RETURN(cloneSimpleFunc(context, originalFunc));
         }
 
         // We will try to track the "best" definition we can find.
@@ -3733,7 +3733,7 @@ namespace Slang
         else
         {
             SLANG_UNEXPECTED("unimplemented");
-            return nullptr;
+            UNREACHABLE_RETURN(nullptr);
         }
     }
 
diff --git a/source/slang/lower-to-ir.cpp b/source/slang/lower-to-ir.cpp
index 93b84ad31..17ebacf98 100644
--- a/source/slang/lower-to-ir.cpp
+++ b/source/slang/lower-to-ir.cpp
@@ -401,7 +401,7 @@ IRValue* getOneValOfType(
     // TODO: should make sure to handle vector and matrix types here
 
     SLANG_UNEXPECTED("inc/dec type");
-    return nullptr;
+    UNREACHABLE_RETURN(nullptr);
 }
 
 LoweredValInfo emitPreOp(
@@ -665,8 +665,10 @@ top:
         {
             auto boundSubscriptInfo = lowered.getBoundSubscriptInfo();
 
-            for (auto getter : getMembersOfType<GetterDecl>(boundSubscriptInfo->declRef))
+            auto getters = getMembersOfType<GetterDecl>(boundSubscriptInfo->declRef);
+            if (getters.Count())
             {
+                auto& getter = *getters.begin();
                 lowered = emitCallToDeclRef(
                     context,
                     boundSubscriptInfo->type,
@@ -677,7 +679,7 @@ top:
             }
 
             SLANG_UNEXPECTED("subscript had no getter");
-            return nullptr;
+            UNREACHABLE_RETURN(nullptr);
         }
         break;
 
@@ -694,7 +696,7 @@ top:
 
     default:
         SLANG_UNEXPECTED("unhandled value flavor");
-        return nullptr;
+        UNREACHABLE_RETURN(nullptr);
     }
 }
 
@@ -733,7 +735,7 @@ RefPtr<Type> getSimpleType(LoweredTypeInfo lowered)
 
     default:
         SLANG_UNEXPECTED("unhandled value flavor");
-        return nullptr;
+        UNREACHABLE_RETURN(nullptr);
     }
 }
 
@@ -1088,7 +1090,7 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
         else
         {
             SLANG_UNIMPLEMENTED_X("codegen for deref expression");
-            return LoweredValInfo();
+            UNREACHABLE_RETURN(LoweredValInfo());
         }
     }
 
@@ -1257,7 +1259,7 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
         else
         {
             SLANG_UNEXPECTED("shouldn't relaly happen");
-            addDirectCallArgs(expr, ioArgs);
+            UNREACHABLE(addDirectCallArgs(expr, ioArgs));
         }
     }
 
@@ -1453,7 +1455,7 @@ struct ExprLoweringVisitorBase : ExprVisitor<Derived, LoweredValInfo>
 
         default:
             SLANG_UNIMPLEMENTED_X("subscript expr");
-            return LoweredValInfo();
+            UNREACHABLE_RETURN(LoweredValInfo());
         }
 
     }
@@ -2016,7 +2018,8 @@ top:
             auto type = subscriptInfo->type;
 
             // Search for an appropriate "setter" declaration
-            for (auto setterDeclRef : getMembersOfType<SetterDecl>(subscriptInfo->declRef))
+            auto setters = getMembersOfType<SetterDecl>(subscriptInfo->declRef);
+            if (setters.Count())
             {
                 auto allArgs = subscriptInfo->args;
                 
@@ -2025,7 +2028,7 @@ top:
                 emitCallToDeclRef(
                     context,
                     context->getSession()->getVoidType(),
-                    setterDeclRef,
+                    *setters.begin(),
                     nullptr,
                     allArgs);
                 return;
@@ -2860,7 +2863,7 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
                     // and then emit a dataflow error if this block
                     // can't be eliminated.
                     SLANG_UNEXPECTED("Needed a return here");
-                    subContext->irBuilder->emitReturn();
+                    UNREACHABLE(subContext->irBuilder->emitReturn());
                 }
             }
         }
diff --git a/source/slang/lower.cpp b/source/slang/lower.cpp
index 0f16a8ad7..429ebbc97 100644
--- a/source/slang/lower.cpp
+++ b/source/slang/lower.cpp
@@ -424,7 +424,7 @@ static SourceLoc getPosition(LoweredExpr const& expr)
     case LoweredExpr::Flavor::VaryingTuple: return expr.getVaryingTupleExpr()->loc;
     default:
         SLANG_UNREACHABLE("all cases handled");
-        return SourceLoc();
+        UNREACHABLE_RETURN(SourceLoc());
     }
 }
 
@@ -902,7 +902,7 @@ struct LoweringVisitor
 
         default:
             SLANG_UNREACHABLE("all cases handled");
-            return LoweredExpr();
+            UNREACHABLE_RETURN(LoweredExpr());
         }
     }
 
diff --git a/source/slang/parameter-binding.cpp b/source/slang/parameter-binding.cpp
index fed838e6b..18294bb3e 100644
--- a/source/slang/parameter-binding.cpp
+++ b/source/slang/parameter-binding.cpp
@@ -567,7 +567,7 @@ getTypeLayoutForGlobalShaderParameter(
 
     default:
         SLANG_UNEXPECTED("unhandled source language");
-        return nullptr;
+        UNREACHABLE_RETURN(nullptr);
     }
 }
 
@@ -1314,7 +1314,7 @@ static RefPtr<TypeLayout> processEntryPointParameter(
     }
 
     SLANG_UNEXPECTED("unhandled type kind");
-    return nullptr;
+    UNREACHABLE_RETURN(nullptr);
 }
 
 static void collectEntryPointParameters(
diff --git a/source/slang/syntax.cpp b/source/slang/syntax.cpp
index 6cf3fd7c9..149e0b811 100644
--- a/source/slang/syntax.cpp
+++ b/source/slang/syntax.cpp
@@ -761,7 +761,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
     bool NamedExpressionType::EqualsImpl(Type * /*type*/)
     {
         SLANG_UNEXPECTED("unreachable");
-        return false;
+        UNREACHABLE_RETURN(false);
     }
 
     Type* NamedExpressionType::CreateCanonicalType()
@@ -772,7 +772,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
     int NamedExpressionType::GetHashCode()
     {
         SLANG_UNEXPECTED("unreachable");
-        return 0;
+        UNREACHABLE_RETURN(0);
     }
 
     // FuncType
@@ -910,7 +910,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
     int TypeType::GetHashCode()
     {
         SLANG_UNEXPECTED("unreachable");
-        return 0;
+        UNREACHABLE_RETURN(0);
     }
 
     // GenericDeclRefType
@@ -1130,7 +1130,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
         SLANG_UNIMPLEMENTED_X("generic substitution into expressions");
 
-        return expr;
+        UNREACHABLE_RETURN(expr);
     }
 
 
@@ -1308,7 +1308,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
         else
         {
             SLANG_UNEXPECTED("unhandled syntax class name");
-            return nullptr;
+            UNREACHABLE_RETURN(nullptr);
         }
     }
 
diff --git a/source/slang/type-layout.cpp b/source/slang/type-layout.cpp
index 0825da6b4..bfdc6c366 100644
--- a/source/slang/type-layout.cpp
+++ b/source/slang/type-layout.cpp
@@ -51,7 +51,7 @@ struct DefaultLayoutRulesImpl : SimpleLayoutRulesImpl
 
         default:
             SLANG_UNEXPECTED("uhandled scalar type");
-            return SimpleLayoutInfo( LayoutResourceKind::Uniform, 0, 1 );
+            UNREACHABLE_RETURN(SimpleLayoutInfo( LayoutResourceKind::Uniform, 0, 1 ));
         }
     }
 
@@ -76,7 +76,7 @@ struct DefaultLayoutRulesImpl : SimpleLayoutRulesImpl
 
         default:
             SLANG_UNEXPECTED("unhandled scalar type");
-            return SimpleLayoutInfo();
+            UNREACHABLE_RETURN(SimpleLayoutInfo());
         }
     }
 
@@ -364,8 +364,6 @@ struct GLSLPushConstantBufferObjectLayoutRulesImpl : GLSLObjectLayoutRulesImpl
         // Special-case the layout for a constant-buffer, because we don't
         // want it to allocate a descriptor-table slot
         return SimpleLayoutInfo(LayoutResourceKind::PushConstantBuffer, 1);
-
-        return GLSLObjectLayoutRulesImpl::GetObjectLayout(kind);
     }
 };
 GLSLPushConstantBufferObjectLayoutRulesImpl kGLSLPushConstantBufferObjectLayoutRulesImpl_;
@@ -401,7 +399,7 @@ struct HLSLObjectLayoutRulesImpl : ObjectLayoutRulesImpl
             // TODO: how to handle these?
         default:
             SLANG_UNEXPECTED("unhandled shader parameter kind");
-            return SimpleLayoutInfo();
+            UNREACHABLE_RETURN(SimpleLayoutInfo());
         }
     }
 };
@@ -717,7 +715,7 @@ static SimpleLayoutInfo getParameterBlockLayoutInfo(
     else
     {
         SLANG_UNEXPECTED("unhandled parameter block type");
-        return SimpleLayoutInfo();
+        UNREACHABLE_RETURN(SimpleLayoutInfo());
     }
 }
 
diff --git a/source/slang/vm.cpp b/source/slang/vm.cpp
index f129d15e0..4b912fb7c 100644
--- a/source/slang/vm.cpp
+++ b/source/slang/vm.cpp
@@ -514,7 +514,7 @@ void computeTypeSizeAlign(
 
     default:
         SLANG_UNIMPLEMENTED_X("type sizing");
-        impl->size = 0;
+        UNREACHABLE(impl->size = 0);
         break;
     }
 
@@ -598,8 +598,8 @@ VMType loadVMType(
             return getType(vmModule->vm, impl);
         }
 
-        SLANG_UNEXPECTED("unimplemented");
-        return VMType();
+        UNREACHABLE(SLANG_UNEXPECTED("unimplemented"));
+        UNREACHABLE_RETURN(VMType());
         break;
     }
 }