[gcc r14-7655] gccrs: libproc_macro: Fix capacity update in tokenstream

[Arthur Cohen]

https://gcc.gnu.org/g:22ba7ea9eecbd1a19757d694b84e5a80b811b003

commit r14-7655-g22ba7ea9eecbd1a19757d694b84e5a80b811b003
Author: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>
Date:   Thu May 18 16:18:58 2023 +0200

    gccrs: libproc_macro: Fix capacity update in tokenstream
    
    The capacity was not updated on tokenstream grow. This commit also add a
    new mechanism to prevent a tokenstream to grow with a zero delta capacity.
    
    libgrust/ChangeLog:
    
            * libproc_macro/tokenstream.cc (TokenStream::grow): Add
            minimum growing capacity.
            (TokenStream::push): Change condition.
    
    Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

Diff:
---
 libgrust/libproc_macro/tokenstream.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libgrust/libproc_macro/tokenstream.cc b/libgrust/libproc_macro/tokenstream.cc
index 12d45431601..25e42dc3dc9 100644
--- a/libgrust/libproc_macro/tokenstream.cc
+++ b/libgrust/libproc_macro/tokenstream.cc
@@ -48,8 +48,9 @@ TokenStream::make_tokenstream (std::uint64_t capacity)
 void
 TokenStream::grow (std::uint64_t delta)
 {
-  auto new_capacity = capacity + delta;
+  auto new_capacity = capacity + (delta != 0 ? delta : 1);
   auto *new_data = new TokenTree[new_capacity];
+  capacity = new_capacity;
   std::memcpy (new_data, data, size);
   delete[] data;
   data = new_data;
@@ -58,7 +59,7 @@ TokenStream::grow (std::uint64_t delta)
 void
 TokenStream::push (TokenTree tree)
 {
-  if (size == capacity)
+  if (size >= capacity)
     grow (capacity);
   data[size] = tree;
   size++;