Work around clang not inferring default args of template template args

Clang 16 fails to compile calls like "gather<Vector>()".

	c++  -O3 -pedantic -std=c++2a -g -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare -Wno-address -frelaxed-template-template-args -Wno-ambiguous-reversed-operator -MD -MP -MF .command_manager.opt.d -c -o .command_manager.opt.o command_manager.cc
	command_manager.cc:825:104: error: no matching function for call to 'gather'
	        auto params = tokens | skip(1) | transform(&Token::content) | filter(std::not_fn(is_switch)) | gather<Vector>();
	                                                                                                       ^~~~~~~~~~~~~~
	./ranges.hh:633:6: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'Container'
	auto gather()
	     ^
	./ranges.hh:642:6: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'Container'
	auto gather()
	     ^
	1 error generated.

because Vector has a defaulted template argument but gather's formal
parameter.

Upstream bug report: llvm/llvm-project#42224
(not sure why it worked for us with Clang 15).

Work around this by adding gather() overloads whose template template
parameter clang can match against Vector. Add another one for HashSet.

GCC rejects calls to these overloads as ambiguous, so use conditional
compilation.

Fixes mawww#4872

src/ranges.hh

@@ -8,6 +8,11 @@
 #include <tuple>
 
 #include "constexpr_utils.hh"
+#ifdef __clang__
+#include "memory.hh"
+#include "meta.hh"
+#include "vector.hh"
+#endif
 
 namespace Kakoune
 {
@@ -638,6 +643,35 @@ auto gather()
     }};
 }
 
+#ifdef __clang__
+
+template <template <typename T,
+                    MemoryDomain domain = memory_domain(Meta::Type<T>{})>
+          class Container>
+auto gather()
+{
+    return ViewFactory{[](auto&& range) {
+        using std::begin; using std::end;
+        using ValueType = std::remove_cv_t<std::remove_reference_t<decltype(*begin(range))>>;
+        return Container<ValueType>(begin(range), end(range));
+    }};
+}
+
+template <template <typename T,
+                    MemoryDomain domain = MemoryDomain::Undefined,
+                    template<typename, MemoryDomain> class C = Vector>
+          class Container>
+auto gather()
+{
+    return ViewFactory{[](auto&& range) {
+        using std::begin; using std::end;
+        using ValueType = std::remove_cv_t<std::remove_reference_t<decltype(*begin(range))>>;
+        return Container<ValueType>(begin(range), end(range));
+    }};
+}
+
+#else
+
 template<template <typename Element> class Container>
 auto gather()
 {
@@ -648,6 +682,8 @@ auto gather()
     }};
 }
 
+#endif
+
 template<typename ExceptionType, bool exact_size, size_t... Indexes>
 auto elements()
 {