shithub: mc

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Improve errors even more.

    Fix cases where we allow unions that are incompatible
    passing through to the backend.

--- a/parse/infer.c

+++ b/parse/infer.c

@@ -357,10 +357,12 @@

     return NULL;

 }

-static Type *delayed(Inferstate *st, Type *fallback)

+static Type *delayeducon(Inferstate *st, Type *fallback)

 {

     Type *t;

+    if (fallback->type != Tyunion)

+        return fallback;

     t = mktylike(fallback->line, fallback->type);

     htput(st->delayed, t, fallback);

     return t;

@@ -627,18 +629,6 @@

         r = b;

     }

-    /* if we have delayed types for a tyvar, transfer it over. */

-    if (a->type == Tyvar && b->type == Tyvar) {

-        if (hthas(st->delayed, a) && !hthas(st->delayed, b))

-            htput(st->delayed, b, htget(st->delayed, a));

-        else if (hthas(st->delayed, b) && !hthas(st->delayed, a))

-            htput(st->delayed, a, htget(st->delayed, b));

-    } else if (hthas(st->delayed, a)) {

-        t = htget(st->delayed, a);

-        if (tybase(t)->type != tybase(b)->type)

-            typeerror(st, t, b, ctx, NULL);

-    }

-

     /* Disallow recursive types */

    if (a->type == Tyvar && b->type != Tyvar)  {

         if (occurs(a, b))

@@ -670,6 +660,16 @@

     mergecstrs(st, ctx, a, b);

     membunify(st, ctx, a, b);

+    /* if we have delayed types for a tyvar, transfer it over. */

+    if (a->type == Tyvar && b->type == Tyvar) {

+        if (hthas(st->delayed, a) && !hthas(st->delayed, b))

+            htput(st->delayed, b, htget(st->delayed, a));

+        else if (hthas(st->delayed, b) && !hthas(st->delayed, a))

+            htput(st->delayed, a, htget(st->delayed, b));

+    } else if (hthas(st->delayed, a)) {

+        unify(st, ctx, htget(st->delayed, a), tybase(b));

+    }

+

     return r;

 }

@@ -918,7 +918,7 @@

     if (uc->etype)

         unify(st, n, uc->etype, type(st, n->expr.args[1]));

     *isconst = n->expr.args[0]->expr.isconst;

-    settype(st, n, delayed(st, t));

+    settype(st, n, delayeducon(st, t));

 }

 static void inferpat(Inferstate *st, Node *n, Node *val, Node ***bind, size_t *nbind)