From b56b655f0bea1922999305d8e88bf16e874098a3 Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Thu, 20 Jul 2017 08:24:33 +0000
Subject: Add checks for locals with type Void

---
 Sil/Check.dcl       |  1 +
 Sil/Check.icl       | 16 ++++++++++++----
 Sil/Syntax.dcl      |  9 +++++++++
 Sil/Syntax.icl      | 20 ++++++++++++++++++++
 examples/errors.sil |  4 ++++
 5 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/Sil/Check.dcl b/Sil/Check.dcl
index 1d5929d..e71448f 100644
--- a/Sil/Check.dcl
+++ b/Sil/Check.dcl
@@ -12,6 +12,7 @@ from Sil.Syntax import :: Program, :: Name
 	| DuplicateLocalName Name Name
 	| ReturnExpressionFromVoidError Name
 	| NoReturnFromNonVoidError Name
+	| LocalVoid Name Name
 
 instance toString CheckError
 
diff --git a/Sil/Check.icl b/Sil/Check.icl
index fc80324..37ee282 100644
--- a/Sil/Check.icl
+++ b/Sil/Check.icl
@@ -28,6 +28,8 @@ where
 		= "Type error: an expression was returned from void function '" <+ f <+ "'."
 	toString (NoReturnFromNonVoidError f)
 		= "Type error: no return from non-void function '" <+ f <+ "'."
+	toString (LocalVoid f l)
+		= "Type error: local variable '" <+ l <+ "' in '" <+ f <+ "' cannot have type Void."
 
 instance <<< CheckError where <<< f e = f <<< toString e <<< "\r\n"
 
@@ -68,12 +70,14 @@ where
 				_              -> False
 
 	checkLocals :: Function -> [CheckError]
-	checkLocals f = check [a.arg_name \\ a <- f.f_args] f.f_code
+	checkLocals f =
+		checkDupName [a.arg_name \\ a <- f.f_args] f.f_code ++
+		concatMap checkVoid (allLocals f)
 	where
-		check :: [Name] CodeBlock -> [CheckError]
-		check defined cb =
+		checkDupName :: [Name] CodeBlock -> [CheckError]
+		checkDupName defined cb =
 			[DuplicateLocalName f.f_name l \\ l <- defined | isMember l locals] ++
-			concatMap (check (locals ++ defined)) (underlyingCBs cb)
+			concatMap (checkDupName (locals ++ defined)) (underlyingCBs cb)
 		where locals = [i.init_name \\ i <- cb.cb_init]
 
 		underlyingCBs :: CodeBlock -> [CodeBlock]
@@ -87,6 +91,10 @@ where
 			findCBs (While _ cb)      = [cb]
 			findCBs (MachineStm _)    = []
 
+		checkVoid :: (Type, Name) -> [CheckError]
+		checkVoid (TVoid, n) = [LocalVoid f.f_name n]
+		checkVoid _          = []
+
 checkErrors :: [(a -> [CheckError])] a *([CheckError], Maybe *File) -> *([CheckError], *Maybe *File)
 checkErrors cks x st = seqSt error (concatMap (flip ($) x) cks) st
 
diff --git a/Sil/Syntax.dcl b/Sil/Syntax.dcl
index 42097c5..1aa0c8b 100644
--- a/Sil/Syntax.dcl
+++ b/Sil/Syntax.dcl
@@ -84,6 +84,15 @@ instance allStatements Function
 instance allStatements CodeBlock
 instance allStatements Statement
 
+class allCodeBlocks a :: a -> [CodeBlock]
+instance allCodeBlocks Function
+instance allCodeBlocks CodeBlock
+instance allCodeBlocks Statement
+
+class allLocals a :: a -> [(Type, Name)]
+instance allLocals Function
+instance allLocals CodeBlock
+
 /**
  * Size of an expression on the stack
  */
diff --git a/Sil/Syntax.icl b/Sil/Syntax.icl
index f78ba83..8083eba 100644
--- a/Sil/Syntax.icl
+++ b/Sil/Syntax.icl
@@ -77,6 +77,26 @@ where
 	allStatements st=:(While _ cb)      = [st:allStatements cb]
 	allStatements st=:(MachineStm _)    = [st]
 
+instance allCodeBlocks Function where allCodeBlocks f = allCodeBlocks f.f_code
+
+instance allCodeBlocks CodeBlock
+where allCodeBlocks cb = [cb:concatMap allCodeBlocks cb.cb_content]
+
+instance allCodeBlocks Statement
+where
+	allCodeBlocks (If bs Nothing)  = concatMap (allCodeBlocks o snd) bs
+	allCodeBlocks (If bs (Just e)) = [e:concatMap (allCodeBlocks o snd) bs]
+	allCodeBlocks (While _ cb)     = [cb]
+	allCodeBlocks _                = []
+
+instance allLocals Function
+where
+	allLocals f = [(a.arg_type, a.arg_name) \\ a <- f.f_args] ++
+		allLocals f.f_code
+
+instance allLocals CodeBlock
+where allLocals cb = [(i.init_type, i.init_name) \\ i <- cb.cb_init]
+
 typeSize :: Type -> Int
 typeSize TVoid = 0
 typeSize TBool = 1
diff --git a/examples/errors.sil b/examples/errors.sil
index 4507097..8bad357 100644
--- a/examples/errors.sil
+++ b/examples/errors.sil
@@ -16,3 +16,7 @@ Void duplicateFunction() {
 Void duplicateLocals(Int a) {
 	Int a;
 }
+
+Void localVoid(Void x) {
+	Void y;
+}
-- 
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