Fix segfault on complex pointer formatting (#642)

fmtlib · Feb 2, 2018 · 8cf30aa · 8cf30aa
1 parent 0555cea
commit 8cf30aa
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Showing 2 changed files with 7 additions and 3 deletions.
diff --git a/fmt/format.h b/fmt/format.h
@@ -3000,13 +3000,13 @@ typename BasicWriter<Char>::CharPtr
       CharPtr p = grow_buffer(fill_size);
       std::uninitialized_fill(p, p + fill_size, fill);
     }
-    CharPtr result = prepare_int_buffer(
-        num_digits, subspec, prefix, prefix_size);
+    std::ptrdiff_t offset = get(prepare_int_buffer(
+        num_digits, subspec, prefix, prefix_size)) - &buffer_[0];
     if (align == ALIGN_LEFT) {
       CharPtr p = grow_buffer(fill_size);
       std::uninitialized_fill(p, p + fill_size, fill);
     }
-    return result;
+    return internal::make_ptr(&buffer_[0], buffer_.size()) + offset;
   }
   unsigned size = prefix_size + num_digits;
   if (width <= size) {

diff --git a/test/format-test.cc b/test/format-test.cc
@@ -1761,3 +1761,7 @@ void convert(int);
 TEST(FormatTest, ConvertCollision) {
   fmt::format("{}", 42);
 }
+
+TEST(FormatTest, Regression) {
+  fmt::format("...........{:<77777.7p}", "foo");
+}