[Bug c/117724] [15 regression] ICE when building libgit2 (error: ‘TYPE_CANONICAL’ is not compatible)

[uecker at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117724

--- Comment #5 from uecker at gcc dot gnu.org ---
Preliminary patch (but does not cover all similar cases):

diff --git a/gcc/tree.cc b/gcc/tree.cc
index 1da06c7d4e9..453b56cc37c 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -13977,6 +13977,9 @@ gimple_canonical_types_compatible_p (const_tree t1,
const_tree t2,
              tree max1 = TYPE_MAX_VALUE (i1);
              tree max2 = TYPE_MAX_VALUE (i2);

+             if (!max1 || !max2)
+               return true;
+
              /* The minimum/maximum values have to be the same.  */
              if ((min1 == min2
                   || (min1 && min2