LWG3820 cartesian_product_view::iterator::prev is not quite right

burblebee · tkoeppe · commit 796bbfc2aadc · 2023-03-07T01:12:55.000Z
diff --git a/source/ranges.tex b/source/ranges.tex
@@ -14602,9 +14602,9 @@
 Equivalent to:
 \begin{codeblock}
 auto& it = std::get<N>(@\exposid{current_}@);
-if (it == ranges::begin(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@))) {
-  it = @\exposid{cartesian-common-arg-end}@(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@));
-  if constexpr (N > 0) {
+if constexpr (N > 0) {
+  if (it == ranges::begin(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@))) {
+    it = @\exposid{cartesian-common-arg-end}@(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@));
     @\exposid{prev}@<N - 1>();
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -14602,9 +14602,9 @@`
`14602`	`14602`	`Equivalent to:`
`14603`	`14603`	`\begin{codeblock}`
`14604`	`14604`	`auto& it = std::get<N>(@\exposid{current_}@);`
`14605`		`-if (it == ranges::begin(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@))) {`
`14606`		`- it = @\exposid{cartesian-common-arg-end}@(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@));`
`14607`		`- if constexpr (N > 0) {`
	`14605`	`+if constexpr (N > 0) {`
	`14606`	`+ if (it == ranges::begin(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@))) {`
	`14607`	`+ it = @\exposid{cartesian-common-arg-end}@(std::get<N>(@\exposid{parent_}@->@\exposid{bases_}@));`
`14608`	`14608`	`@\exposid{prev}@<N - 1>();`
`14609`	`14609`	`}`
`14610`	`14610`	`}`