From 62c9c126ed3eedf981cc087938fd98f7afb17506 Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Thu, 20 Jul 2017 20:40:38 +0000
Subject: Check the type of the main function (should be Void)

---
 Sil/Check.icl | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

(limited to 'Sil/Check.icl')

diff --git a/Sil/Check.icl b/Sil/Check.icl
index 61f5ac7..9b24f50 100644
--- a/Sil/Check.icl
+++ b/Sil/Check.icl
@@ -8,6 +8,7 @@ import StdOverloaded
 import StdString
 import StdTuple
 
+import Data.Error
 from Data.Func import $, mapSt, seqSt
 import Data.List
 import Data.Maybe
@@ -21,13 +22,15 @@ instance toString CheckError
 where
 	toString NoMainFunction
 		= "Error: no main function."
+	toString (MainFunctionInvalidType t)
+		= "Error: function 'main' should have type Void but has type " <+ t <+ "."
 	toString (DuplicateFunctionName n)
 		= "Error: multiply defined: '" <+ n <+ "'."
 	toString (DuplicateLocalName f arg)
 		= "Error: multiply defined: '" <+ arg <+ "' in '" <+ f <+ "'."
-	toString (ReturnExpressionFromVoidError f)
+	toString (ReturnExpressionFromVoid f)
 		= "Type error: an expression was returned from void function '" <+ f <+ "'."
-	toString (NoReturnFromNonVoidError f)
+	toString (NoReturnFromNonVoid 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."
@@ -36,7 +39,10 @@ instance <<< CheckError where <<< f e = f <<< toString e <<< "\r\n"
 
 checkProgram :: *(Maybe *File) Program -> *([CheckError], *Maybe *File)
 checkProgram err prog
-	= checkErrors [checkFunctionNames, checkMainFunction] prog
+	= checkErrors
+	[ checkFunctionNames
+	, checkMainFunction
+	] prog
 	$ appFst flatten $ mapSt (flip checkFunction) prog.p_funs err
 where
 	checkMainFunction :: Program -> [CheckError]
@@ -51,14 +57,18 @@ where
 		| not (isEmpty fs) && isMember (hd fs) (tl fs)]
 
 checkFunction :: *(Maybe *File) Function -> *([CheckError], *Maybe *File)
-checkFunction err f = checkErrors [checkLocals, checkReturnAndVoid] f $ noErrors err
+checkFunction err f = checkErrors
+	[ checkLocals
+	, checkReturnAndVoid
+	, checkMainFunctionType
+	] f $ noErrors err
 where
 	checkReturnAndVoid :: Function -> [CheckError]
 	checkReturnAndVoid f = case f.f_type of
 		TVoid -> case [st \\ st=:(Return (Just _)) <- allStatements f] of
 			[] -> []
-			_  -> [ReturnExpressionFromVoidError f.f_name]
-		_     -> if (sureToReturn f.f_code) [] [NoReturnFromNonVoidError f.f_name]
+			_  -> [ReturnExpressionFromVoid f.f_name]
+		_     -> if (sureToReturn f.f_code) [] [NoReturnFromNonVoid f.f_name]
 	where
 		sureToReturn :: CodeBlock -> Bool
 		sureToReturn cb = case cb.cb_content of
@@ -70,6 +80,11 @@ where
 				If bs Nothing  -> all (sureToReturn o snd) bs
 				_              -> False
 
+	checkMainFunctionType :: Function -> [CheckError]
+	checkMainFunctionType f=:{f_name="main",f_type=TVoid,f_args=[]} = []
+	checkMainFunctionType f=:{f_name="main"} = [MainFunctionInvalidType $ fromOk $ fromJust $ type zero f]
+	checkMainFunctionType _ = []
+
 	checkLocals :: Function -> [CheckError]
 	checkLocals f =
 		checkDupName [a.arg_name \\ a <- f.f_args] f.f_code ++
-- 
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