shithub: mc

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Keep a list of impls for a given type.

	We want to know so we can unify in a post check.

--- a/parse/gram.y

+++ b/parse/gram.y

@@ -382,7 +382,8 @@

 	;

 traitdef: Ttrait Tident generictype optauxtypes { /* trait prototype */

-		$$ = mktrait($1->loc, mkname($2->loc, $2->id), $3,

+		$$ = mktrait($1->loc,

+			mkname($2->loc, $2->id), $3,

 			$4.types, $4.ntypes,

 			NULL, 0,

 			NULL, 0,

@@ -390,7 +391,8 @@

 	}

 	| Ttrait Tident generictype optauxtypes Tasn traitbody Tendblk /* trait definition */ {

 		size_t i;

-		$$ = mktrait($1->loc, mkname($2->loc, $2->id), $3,

+		$$ = mktrait($1->loc,

+			mkname($2->loc, $2->id), $3,

 			$4.types, $4.ntypes,

 			NULL, 0,

 			$6.nl, $6.nn,

@@ -397,6 +399,7 @@

 			0);

 		for (i = 0; i < $6.nn; i++) {

 			$6.nl[i]->decl.trait = $$;

+			$6.nl[i]->decl.impls = mkht(tyhash, tyeq); 

 			$6.nl[i]->decl.isgeneric = 1;

 		}

 	}

--- a/parse/infer.c

+++ b/parse/infer.c

@@ -466,20 +466,28 @@

 	return t;

 }

-static Type *tysubst(Inferstate *st, Type *t, Type *orig)

+static Type *tysubstmap(Inferstate *st, Htab *subst, Type *t, Type *orig)

 {

-	Htab *subst;

 	size_t i;

-	subst = mkht(tyhash, tyeq);

 	for (i = 0; i < t->ngparam; i++) {

 		htput(subst, t->gparam[i], tf(st, orig->arg[i]));

 	}

 	t = tyfreshen(st, subst, t);

+	return t;

+}

+

+static Type *tysubst(Inferstate *st, Type *t, Type *orig)

+{

+	Htab *subst;

+

+	subst = mkht(tyhash, tyeq);

+	t = tysubstmap(st, subst, t, orig);

 	htfree(subst);

 	return t;

 }

+

 /* fixd the most accurate type mapping we have (ie,

  * the end of the unification chain */

 static Type *tf(Inferstate *st, Type *orig)

@@ -1058,16 +1066,27 @@

 static Type *initvar(Inferstate *st, Node *n, Node *s)

 {

-	Type *t;

+	Type *t, *param;

+	Htab *subst;

 	if (s->decl.ishidden)

 		fatal(n, "attempting to refer to hidden decl %s", ctxstr(st, n));

-	if (s->decl.isgeneric)

-		t = tysubst(st, tf(st, s->decl.type), s->decl.type);

-	else

+

+	param = NULL;

+	if (s->decl.isgeneric) {

+		subst = mkht(tyhash, tyeq);

+		t = tysubstmap(st, subst, tf(st, s->decl.type), s->decl.type);

+		if (s->decl.trait) {

+			param = htget(subst, s->decl.trait->param);

+			delayedcheck(st, n, curstab());

+		}

+		htfree(subst);

+	} else {

 		t = s->decl.type;

+	}

 	n->expr.did = s->decl.did;

 	n->expr.isconst = s->decl.isconst;

+	n->expr.param = param;

 	if (s->decl.isgeneric && !st->ingeneric) {

 		t = tyfreshen(st, NULL, t);

 		addspecialization(st, n, curstab());

@@ -1625,6 +1644,7 @@

 			fatal(n, "trait %s already specialized with %s on %s:%d",

 				namestr(t->name), tystr(n->impl.type),

 				fname(sym->loc), lnum(sym->loc));

+		htput(proto->decl.impls, n->impl.type, ty);

 		dcl->decl.name = name;

 		putdcl(file->file.globls, dcl);

 		if (debugopt['S'])

@@ -1971,7 +1991,11 @@

 	Type *ty;

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

-	ty = tyfreshen(st, NULL, type(st, dcl));

+	if (n->expr.param) {

+		ty = htget(dcl->decl.impls, tf(st, n->expr.param));

+	} else {

+		ty = tyfreshen(st, NULL, type(st, dcl));

+	}

 	unify(st, n, type(st, n), ty);

 }

--- a/parse/parse.h

+++ b/parse/parse.h

@@ -236,10 +236,11 @@

 		struct {

 			Op op;

 			Type *type;

+			Type *param;	/* for specialized traits, the primary param */

 			int isconst;

-			size_t did; /* for Ovar, we want a mapping to the decl id */

+			size_t did;	/* for Ovar, we want a mapping to the decl id */

 			size_t nargs;

-			Node *idx; /* used when this is in an indexed initializer */

+			Node *idx;	/* used when this is in an indexed initializer */

 			Node **args;

 		} expr;

@@ -317,6 +318,7 @@

 			 impl.

 			*/

 			Trait *trait;

+			Htab *impls;

 			char vis;

 			/* flags */