LWG3880 Clarify operator+= complexity for {chunk,stride}_view::iterator

Author: burblebee

source/ranges.tex

@@ -12504,7 +12504,8 @@
 Equivalent to:
 \begin{codeblock}
 if (x > 0) {
-  @\exposid{missing_}@ = ranges::advance(@\exposid{current_}@, @\exposid{n_}@ * x, @\exposid{end_}@);
+  ranges::advance(@\exposid{current_}@, @\exposid{n_}@ * (x - 1));
+  @\exposid{missing_}@ = ranges::advance(@\exposid{current_}@, @\exposid{n_}@, @\exposid{end_}@);
 } else if (x < 0) {
   ranges::advance(@\exposid{current_}@, @\exposid{n_}@ * x + @\exposid{missing_}@);
   @\exposid{missing_}@ = 0;
@@ -14067,7 +14068,8 @@
 Equivalent to:
 \begin{codeblock}
 if (n > 0) {
-  @\exposid{missing_}@ = ranges::advance(@\exposid{current_}@, @\exposid{stride_}@ * n, @\exposid{end_}@);
+  ranges::advance(@\exposid{current_}@, @\exposid{stride_}@ * (n - 1));
+  @\exposid{missing_}@ = ranges::advance(@\exposid{current_}@, @\exposid{stride_}@, @\exposid{end_}@);
 } else if (n < 0) {
   ranges::advance(@\exposid{current_}@, @\exposid{stride_}@ * n + @\exposid{missing_}@);
   @\exposid{missing_}@ = 0;