From d3da4d01b2324b1dfec9a4fefe0ae2760a95db37 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Sun, 14 Aug 2022 14:05:02 +0100
Subject: [PATCH] Improve folding of for-generate expressions. Issue #514

---
 src/elab.c             | 17 +++++++++++++++--
 test/elab/issue514.vhd | 42 ++++++++++++++++++++++++++++++++++++++++++
 test/test_elab.c       | 20 ++++++++++++++++++++
 3 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 test/elab/issue514.vhd

diff --git a/src/elab.c b/src/elab.c
index 5e567dcb..9037c75a 100644
--- a/src/elab.c
+++ b/src/elab.c
@@ -1395,8 +1395,21 @@ static void elab_generate_range(tree_t r, int64_t *low, int64_t *high,
       error_at(tree_loc(r), "generate range is not static");
       *low = *high = 0;
    }
-   else
-      range_bounds(r, low, high);
+   else if (!folded_bounds(r, low, high)) {
+      tree_t left  = eval_must_fold(ctx->eval, tree_left(r));
+      tree_t right = eval_must_fold(ctx->eval, tree_right(r));
+
+      int64_t ileft, iright;
+      if (folded_int(left, &ileft) && folded_int(right, &iright)) {
+         const bool asc = (tree_subkind(r) == RANGE_TO);
+         *low = asc ? ileft : iright;
+         *high = asc ? iright : ileft;
+      }
+      else {
+         error_at(tree_loc(r), "generate range is not static");
+         *low = *high = 0;
+      }
+   }
 }
 
 static void elab_for_generate(tree_t t, elab_ctx_t *ctx)
diff --git a/test/elab/issue514.vhd b/test/elab/issue514.vhd
new file mode 100644
index 00000000..3c95655e
--- /dev/null
+++ b/test/elab/issue514.vhd
@@ -0,0 +1,42 @@
+package pack is
+    type params is record
+        x, y : integer;
+    end record;
+end package;
+
+-------------------------------------------------------------------------------
+
+use work.pack.all;
+
+entity sub is
+    generic ( p : params );
+end entity;
+
+architecture test of sub is
+    constant px : integer := p.x;
+    constant py : integer := p.y;
+begin
+
+    g: for i in px to py generate
+    end generate;
+
+end architecture;
+
+-------------------------------------------------------------------------------
+
+use work.pack.all;
+
+entity issue514 is
+end entity;
+
+architecture test of issue514 is
+    function get_params return params is
+    begin
+        return (x => 4, y => 6);
+    end function;
+begin
+
+    u: entity work.sub
+        generic map (p => get_params);
+
+end architecture;
diff --git a/test/test_elab.c b/test/test_elab.c
index 9e2fa133..9e7227d4 100644
--- a/test/test_elab.c
+++ b/test/test_elab.c
@@ -1177,6 +1177,25 @@ START_TEST(test_comp4)
 }
 END_TEST
 
+START_TEST(test_issue514)
+{
+   input_from_file(TESTDIR "/elab/issue514.vhd");
+
+   tree_t e = run_elab();
+   fail_if(e == NULL);
+
+   tree_t b0 = tree_stmt(e, 0);
+   fail_unless(tree_ident(b0) == ident_new("ISSUE514"));
+   fail_unless(tree_stmts(b0) == 1);
+
+   tree_t u = tree_stmt(b0, 0);
+   fail_unless(tree_ident(u) == ident_new("U"));
+   fail_unless(tree_stmts(u) == 3);
+
+   fail_if_errors();
+}
+END_TEST
+
 Suite *get_elab_tests(void)
 {
    Suite *s = suite_create("elab");
@@ -1244,6 +1263,7 @@ Suite *get_elab_tests(void)
    tcase_add_test(tc, test_neorv1);
    tcase_add_test(tc, test_toplevel4);
    tcase_add_test(tc, test_comp4);
+   tcase_add_test(tc, test_issue514);
    suite_add_tcase(s, tc);
 
    return s;
-- 
2.39.2