From f8a8add7d0e74d20304b3194e836752a9986ddc3 Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Mon, 8 Aug 2022 09:16:13 +0200
Subject: direct access of eunion fields

---
 bootstrap/all.h     |  3 ++-
 bootstrap/cgen.c    | 10 ++++++++--
 bootstrap/parse.c   | 22 ++++++++++++++++++----
 bootstrap/test2.cff |  6 +++---
 bootstrap/types.c   |  1 +
 5 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/bootstrap/all.h b/bootstrap/all.h
index 1629455..373aac9 100644
--- a/bootstrap/all.h
+++ b/bootstrap/all.h
@@ -312,6 +312,7 @@ enum exprtype {
    Eslice,
    Elen,
    Eeuini,
+   Eeutag,
 };
 
 struct blockstmt {
@@ -353,7 +354,7 @@ struct expr {
          struct expr *lhs, *rhs;
       } index;
       struct blockstmt block;
-      struct expr *child; // cast, len
+      struct expr *child; // cast, len, eutag
       struct {
          i64 i;
          const char *vname;
diff --git a/bootstrap/cgen.c b/bootstrap/cgen.c
index 433a5a0..f54eccc 100644
--- a/bootstrap/cgen.c
+++ b/bootstrap/cgen.c
@@ -249,7 +249,10 @@ genexpr(struct expr *ex) {
       pri("((%t)%n)", ty, ex);
       break;
    case Eget:
-      pri("%e%s%s", ex->get.lhs, ex->get.lhs->ty->t == TYptr ? "->" : ".", ex->get.fld);
+      pri("%e%s%s%s", ex->get.lhs, ex->get.lhs->ty->t == TYptr ? "->" : ".",
+          (ex->get.lhs->ty->t == TYeunion
+           || (ex->get.lhs->ty->t == TYptr && ex->get.lhs->ty->child->t == TYeunion) ? "u." : ""),
+           ex->get.fld);
       break;
    case Emcall:
       decl = container_of(ex->mcall.met, struct decl, fn);
@@ -273,6 +276,9 @@ genexpr(struct expr *ex) {
    case Elen:
       pri("%e.len", ex->child);
       break;
+   case Eeutag:
+      pri("%e%st", ex->child, ex->child->ty->t == TYptr ? "->" : ".");
+      break;
    case Eeuini:
       pri("((%t)", ty);
       geneuiniex(ex);
@@ -470,7 +476,7 @@ liftnestedex(struct expr *ex) {
    case Eblock:
       liftnested(blocktostmt(ex->block));
       break;
-   case Eas: case Elen:
+   case Eas: case Elen: case Eeutag:
       liftnestedex(ex->child);
       break;
    case Eini:
diff --git a/bootstrap/parse.c b/bootstrap/parse.c
index 93a3afb..3e14dc3 100644
--- a/bootstrap/parse.c
+++ b/bootstrap/parse.c
@@ -371,6 +371,8 @@ lex(struct parser *P) {
          tok.t = '##';
       } else if (!strcmp(s, "#len")) {
          tok.t = '#len';
+      } else if (!strcmp(s, "#tag")) {
+         tok.t = '#tag';
       } else if (!strcmp(s, "#?")) {
          tok.t = '#?';
       } else if (!strncmp(s, "#:", 2)) {
@@ -1284,27 +1286,39 @@ pexpostfix(struct parser *P) {
          if (ty->t == TYarr) {
             assert(ty->length >= 0);
             ex.t = Eintlit;
-            ex.ty = ty_usize;
+            ex.ty = ty->konst ? constify(ty_usize) : ty_usize;
             ex.span = tok.span;
             ex.i = ty->length;
          } else if (ty->t == TYslice) {
             ex.child = exprdup(ex);
             ex.t = Elen;
-            ex.ty = ty_usize;
+            ex.ty = ty->konst ? constify(ty_usize) : ty_usize;
             ex.span = tok.span;
          } else {
             fatal(P, ex.span, "invalid operand to `.#len' (%t)", ex.ty);
          }
+      } else if (lexmatch (P, &tok, '#tag')) {
+         const struct type *ty = ex.ty;
+         if (ty->t == TYptr)
+            ty = ty->child;
+         if (ty->t != TYeunion)
+            fatal(P, ex.span, "invalid operand to `.#tag' (%t)", ex.ty);
+         ex.child = exprdup(ex);
+         ex.t = Eeutag;
+         ex.ty = ty->konst ? constify(ty->agg.enumty) : ty->agg.enumty;
+         ex.span = tok.span;
       } else {
          const char *fnam = (tok = lexexpect(P, TKident)).str;
          const struct type *ty = ex.ty;
          if (ty->t == TYptr)
             ty = ty->child;
-         if (ty->t == TYstruct || ty->t == TYunion) {
+         if (ty->t == TYstruct || ty->t == TYunion || ty->t == TYeunion) {
             int idx = structfldnam2idx(ty, fnam);
             struct aggfield *fld = &ty->agg.flds.d[idx];
             if (idx < 0)
                fatal(P, tok.span, "%t has no such field `%s'", ty, fnam);
+            if (!fld->ty)
+               fatal(P, tok.span, "%t variant `%s' is empty", ty, fnam);
             
             ex.get.lhs = exprdup(ex);
             ex.t = Eget;
@@ -1748,7 +1762,7 @@ parsevardecl(decl_yielder_t yield, void *yarg, struct parser *P, bool let, bool
 
       if (lexmatch(P, NULL, '=')) {
          ini = exprdup(parseexpr(P));
-         ty = ini->ty;
+         ty = unconstify(ini->ty);
       } else {
          ty = parsetype(P);
          if (lexmatch(P, NULL, '=')) {
diff --git a/bootstrap/test2.cff b/bootstrap/test2.cff
index fdb30cb..ec5fcb0 100644
--- a/bootstrap/test2.cff
+++ b/bootstrap/test2.cff
@@ -36,15 +36,15 @@ extern fn main() void {
    let x int #?;
    x = X + 1 + Y;
 
-   let v= Value:None;
-   v = :Int 3;
+   let const v= Value:None;
    switch (v) {
    case None;
    case Int i;
       i;
    case Flo *f;
-      *f += 1.0f;
    }
+   let t = v.#tag;
+   let i = v.Int;
 
    #:outer for let i = 0; i++ < 10; {
       printf("%d\n", i);
diff --git a/bootstrap/types.c b/bootstrap/types.c
index 38d75d0..78a3df0 100644
--- a/bootstrap/types.c
+++ b/bootstrap/types.c
@@ -313,6 +313,7 @@ arraydecay(const struct type *ty) {
 
 int
 numtype2rank(const struct type *a) {
+   a = unconstify(a);
    if (a->t == TYint) {
       if (a->size < g_targ.intsize || a == ty_int)
          return 0;
-- 
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