shithub: mc

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Fix generic union constructor inference in pattern matching.

--- a/parse/infer.c

+++ b/parse/infer.c

@@ -844,13 +844,27 @@

         n->expr.isconst = n->expr.isconst && n->expr.args[i]->expr.isconst;

         types[i] = type(st, n->expr.args[i]);

     }

+    *isconst = n->expr.isconst;

     settype(st, n, mktytuple(n->line, types, n->expr.nargs));

 }

+static void inferucon(Inferstate *st, Node *n, int *isconst)

+{

+    Ucon *uc;

+    Type *t;

+

+    uc = uconresolve(st, n);

+    t = tyfreshen(st, tf(st, uc->utype));

+    uc = tybase(t)->udecls[uc->id];

+    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));

+}

+

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

 {

     size_t i;

-    Ucon *uc;

     Node **args;

     Node *s;

     Type *t;

@@ -861,10 +875,7 @@

             inferpat(st, args[i], val, bind, nbind);

     switch (exprop(n)) {

         case Oucon:

-            uc = uconresolve(st, n);

-            if (uc->etype)

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

-            settype(st, n, delayed(st, uc->utype));

+            inferucon(st, n, &n->expr.isconst);

             break;

         case Ovar:

             s = getdcl(curstab(), args[0]);

@@ -913,7 +924,6 @@

 {

     Node **args;

     size_t i, nargs;

-    Ucon *uc;

     Node *s;

     Type *t;

@@ -1055,12 +1065,7 @@

             }

             break;

         case Oucon:

-            uc = uconresolve(st, n);

-            t = tyfreshen(st, tf(st, uc->utype));

-            uc = tybase(t)->udecls[uc->id];

-            if (uc->etype)

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

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

+            inferucon(st, n, &n->expr.isconst);

             break;

         case Otup:

             infertuple(st, n, &n->expr.isconst);