c++: Fix bootstrap on 32-bit hosts [PR91828]

Using the releasing_vec op[] with an int index was breaking on 32-bit hosts
because of ambiguity with the built-in operator and the conversion
function.  Since the built-in operator has a ptrdiff_t, this was fine on
64-bit targets where ptrdiff_t is larger than int, but broke on 32-bit
targets where it's the same as int, making the conversion for that argument
better than the member function.  Fixed by changing the member function to
also use ptrdiff_t for the index.

gcc/cp/ChangeLog:

	* cp-tree.h (releasing_vec::operator[]): Change parameter type to
	ptrdiff_t.

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 081ede24e969c6e4ef4328e3188d3e04533b6118..f28291e46d705e937b91e77063d8294e95331e12 100644 (file)
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -975,8 +975,10 @@ public:
   operator vec_t *() const { return v; }
   vec_t ** operator& () { return &v; }
 
-  /* Breaks pointer/value consistency for convenience.  */
-  tree& operator[] (unsigned i) const { return (*v)[i]; }
+  /* Breaks pointer/value consistency for convenience.  This takes ptrdiff_t
+     rather than unsigned to avoid ambiguity with the built-in operator[]
+     (bootstrap/91828).  */
+  tree& operator[] (ptrdiff_t i) const { return (*v)[i]; }
 
   ~releasing_vec() { release_tree_vector (v); }
 private: