[gcc/devel/rust/master] Fix size used in unsized adjustments

[gcc/devel/rust/master] Fix size used in unsized adjustments

[Thomas Schwinge]

https://gcc.gnu.org/g:f5bceb679420b999aa63c1b34dd0e0075cf9c5fd

commit f5bceb679420b999aa63c1b34dd0e0075cf9c5fd
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Wed May 4 13:48:03 2022 +0100

    Fix size used in unsized adjustments
    
    When we coerce from an array to a slice we take the full capacity of the
    array as the size to the FatPtr slice object but this was off by one. This
    The TYPE_MAX_VALUE is not the correct method of accessing this but instead
    it needs to take into account other values to get the correct HOST_WIDE_INT

Diff:
---
 gcc/rust/backend/rust-compile-expr.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 41f8c0a5ce4..1cf4e3d5499 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -1348,7 +1348,13 @@ HIRCompileBase::resolve_unsized_adjustment (Resolver::Adjustment &adjustment,
 
   // fetch the size from the domain
   tree domain = TYPE_DOMAIN (expr_type);
-  tree size = TYPE_MAX_VALUE (domain);
+  unsigned HOST_WIDE_INT array_size
+    = wi::ext (wi::to_offset (TYPE_MAX_VALUE (domain))
+		 - wi::to_offset (TYPE_MIN_VALUE (domain)) + 1,
+	       TYPE_PRECISION (TREE_TYPE (domain)),
+	       TYPE_SIGN (TREE_TYPE (domain)))
+	.to_uhwi ();
+  tree size = build_int_cst (size_type_node, array_size);
 
   return ctx->get_backend ()->constructor_expression (fat_pointer, false,
 						      {data, size}, -1, locus);