[ranges.syn] Don't constrain specializations of enable_borrowed_range (cplusplus#4519)

CaseyCarter · web-flow · commit 2fdafbee1526 · 2021-03-13T00:29:26.000+01:00
These constraints redundantly repeat the constraints from the template we're partially specializing for. This isn't incorrect, but it is unnecessary, adds opportunities for editorial errors, and is inconsistent with how other partial specializations of templates for constrained types are specified.
diff --git a/source/ranges.tex b/source/ranges.tex
@@ -127,7 +127,7 @@
     requires (K == subrange_kind::sized || !@\libconcept{sized_sentinel_for}@<S, I>)
   class subrange;
 
-  template<@\libconcept{input_or_output_iterator}@ I, @\libconcept{sentinel_for}@<I> S, subrange_kind K>
+  template<class I, class S, subrange_kind K>
     inline constexpr bool enable_borrowed_range<subrange<I, S, K>> = true;
 
   // \ref{range.dangling}, dangling iterator handling
@@ -168,7 +168,7 @@
     requires @\exposconcept{weakly-equality-comparable-with}@<W, Bound> && @\libconcept{semiregular}@<W>
   class iota_view;
 
-  template<@\libconcept{weakly_incrementable}@ W, @\libconcept{semiregular}@ Bound>
+  template<class W, class Bound>
     inline constexpr bool enable_borrowed_range<iota_view<W, Bound>> = true;
 
   namespace views { inline constexpr @\unspec@ iota = @\unspec@; }
