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Unify the types for traits correctly.

--- a/parse/gram.y

+++ b/parse/gram.y

@@ -335,10 +335,10 @@

         ;

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

-                $$ = mktrait($1->line, mkname($2->line, $2->str), NULL, 0, NULL, 0, 1);

+                $$ = mktrait($1->line, mkname($2->line, $2->str), $3, NULL, 0, NULL, 0, 1);

             }

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

-                $$ = mktrait($1->line, mkname($2->line, $2->str), NULL, 0, $5.nl, $5.nn, 0);

+                $$ = mktrait($1->line, mkname($2->line, $2->str), $3, NULL, 0, $5.nl, $5.nn, 0);

             }

         ;

--- a/parse/infer.c

+++ b/parse/infer.c

@@ -529,7 +529,7 @@

 }

 /* does b satisfy all the constraints of a? */

-static int traitcheck(Type *a, Type *b)

+static int checktraits(Type *a, Type *b)

 {

     /* a has no traits to satisfy */

     if (!a->traits)

@@ -558,7 +558,7 @@

         else if (b->traits)

             a->traits = bsdup(b->traits);

     } else {

-        if (!traitcheck(a, b)) {

+        if (!checktraits(a, b)) {

             sep = "";

             n = 0;

             for (i = 0; bsiter(a->traits, &i); i++) {

@@ -1298,8 +1298,10 @@

 static void specializeimpl(Inferstate *st, Node *n)

 {

-    Trait *t;

     Node *dcl, *proto;

+    Htab *ht;

+    Trait *t;

+    Type *ty;

     size_t i, j;

     t = gettrait(curstab(), n->impl.traitname);

@@ -1323,8 +1325,14 @@

                   namestr(dcl), namestr(t->name), ctxstr(st, n));

         /* infer and unify types */

+        checktraits(t->param, n->impl.type);

+        ht = mkht(tyhash, tyeq);

+        htput(ht, t->param, n->impl.type);

+        ty = tyspecialize(type(st, proto), ht);

+        htfree(ht);

+

         inferdecl(st, dcl);

-        unify(st, n, type(st, dcl), type(st, proto));

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

     }

 }

@@ -1503,9 +1511,9 @@

             fatal(ctx->line, "Type %s not compatible with %s near %s\n", tystr(t), tystr(delayed), ctxstr(st, ctx));

     }

     if (t->type == Tyvar) {

-        if (hastrait(t, traittab[Tcint]) && traitcheck(t, tyint))

+        if (hastrait(t, traittab[Tcint]) && checktraits(t, tyint))

             return tyint;

-        if (hastrait(t, traittab[Tcfloat]) && traitcheck(t, tyflt))

+        if (hastrait(t, traittab[Tcfloat]) && checktraits(t, tyflt))

             return tyflt;

     } else if (!t->fixed) {

         t->fixed = 1;

--- a/parse/parse.h

+++ b/parse/parse.h

@@ -148,8 +148,9 @@

 struct Trait {

     int cid;            /* unique id */

-    int isproto;        /* is it a prototype for exporting */

+    int isproto;        /* is it a prototype (for exporting purposes) */

     Node *name;         /* the name of the trait */

+    Type *param;        /* the type parameter */

     Node **memb;        /* type must have these members */

     size_t nmemb;

     Node **funcs;       /* and declare these funcs */

@@ -409,7 +410,7 @@

 Type *mktyfunc(int line, Node **args, size_t nargs, Type *ret);

 Type *mktystruct(int line, Node **decls, size_t ndecls);

 Type *mktyunion(int line, Ucon **decls, size_t ndecls);

-Trait *mktrait(int line, Node *name, Node **memb, size_t nmemb, Node **funcs, size_t nfuncs, int isproto);

+Trait *mktrait(int line, Node *name, Type *param, Node **memb, size_t nmemb, Node **funcs, size_t nfuncs, int isproto);

 Type *mktylike(int line, Ty ty); /* constrains tyvar t like it was builtin ty */

 int   istysigned(Type *t);

 int   istyfloat(Type *t);

--- a/parse/type.c

+++ b/parse/type.c

@@ -111,12 +111,13 @@

 }

 /* steals memb, funcs */

-Trait *mktrait(int line, Node *name, Node **memb, size_t nmemb, Node **funcs, size_t nfuncs, int isproto)

+Trait *mktrait(int line, Node *name, Type *param, Node **memb, size_t nmemb, Node **funcs, size_t nfuncs, int isproto)

 {

     Trait *t;

     t = zalloc(sizeof(Trait));

     t->name = name;

+    t->param = param;

     t->memb = memb;

     t->nmemb = nmemb;

     t->funcs = funcs;

@@ -642,8 +643,10 @@

     int i;

     Type *ty;

+/* this must be done after all the types are created, otherwise we will

+ * clobber the memoized bunch of types with the type params. */

 #define Tc(c, n) \

-    mktrait(-1, mkname(-1, n), NULL, 0, NULL, 0, 0);

+    mktrait(-1, mkname(-1, n), NULL, NULL, 0, NULL, 0, 0);

 #include "trait.def"

 #undef Tc