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Error on unmatchable types.

--- a/mi/match.c

+++ b/mi/match.c

@@ -199,8 +199,8 @@

 	case Tyvar: case Typaram: case Tyunres: case Tyname:

 	case Tybad: case Tyvalist: case Tygeneric: case Ntypes:

 	case Tyfunc: case Tycode:

-			die("Invalid constructor type %s in match", tystr(t));

-			break;

+		die("Invalid constructor type %s in match", tystr(t));

+		break;

 	}

 	return 0;

 }

@@ -252,6 +252,11 @@

 	return istyprimitive(ty) || ty->type == Tyvoid || ty->type == Tyfunc;

 }

+static int ismatchable(Type *ty)

+{

+	return ty->type != Tyfunc && ty->type != Tycode && ty->type != Tyvalist;

+}

+

 static int addwildrec(Srcloc loc, Type *ty, Dtree *start, Dtree *accept, Dtree ***end, size_t *nend)

 {

 	Dtree *next, **last, **tail;

@@ -349,10 +354,9 @@

 		break;

 	case Typtr:

 		ret = addwildrec(loc, ty->sub[0], start, accept, &last, &nlast);

-	default:

-		ret = 1;

-		lappend(&last, &nlast, accept);

 		break;

+	default:

+		die("unreachable");

 	}

 	lcat(end, nend, last, nlast);

 	lfree(&last, &nlast);

@@ -615,10 +619,13 @@

 	switch (exprop(pat)) {

 	case Ovar:

 		dcl = decls[pat->expr.did];

-		if (dcl->decl.isconst)

+		if (dcl->decl.isconst) {

+			if (!ismatchable(decltype(dcl)))

+				fatal(dcl, "matching unmatchable type %s", tystr(decltype(dcl)));

 			ret = addpat(dcl->decl.init, val, start, accept, cap, ncap, end, nend);

-		else

+		} else {

 			ret = addwild(pat, val, start, accept, cap, ncap, end, nend);

+		}

 		break;

 	case Oucon:

 		ret = addunion(pat, val, start, accept, cap, ncap, end, nend);

--- a/parse/types.def

+++ b/parse/types.def

@@ -45,4 +45,4 @@

 Ty(Tyunres, NULL, 1) /* unresolved */

 Ty(Tyname, NULL, 1)

 Ty(Tygeneric, NULL, 1)

-Ty(Tycode, NULL, 0)

+Ty(Tycode, NULL, 0)	/* code ptr without env: backend-only */