minimum Clang version

[wojdyr]

The documentation in docs/index.rst says "Clang 7+", but I couldn't compile it with Clang < 9.

Clang 7:

nanobind/ext/robin_map/include/tsl/robin_hash.h:258:13: error: no member named
      'launder' in namespace 'std'; did you mean 'rand_r'?
    return *std::launder(

Clang 8:

nanobind/include/nanobind/nb_tuple.h:35:5: error: exception specification of
      explicitly defaulted move constructor does not match the calculated one
    tuple(tuple &&) noexcept = default;

For Clang 8, it's enough to remove noexcept in two places to make it compile.
Alternatively, the compiler requirement could be changed to "Clang 9+".

[wjakob]

For Clang 8, which are the two places where noexcept should be removed? (you listed one)

[wojdyr]

diff --git a/include/nanobind/nb_tuple.h b/include/nanobind/nb_tuple.h
index a04b466..ab2c292 100644
--- a/include/nanobind/nb_tuple.h
+++ b/include/nanobind/nb_tuple.h
@@ -32,8 +32,8 @@ template <typename T, typename... Ts> struct tuple<T, Ts...> : tuple<Ts...> {
 
     tuple() = default;
     tuple(const tuple &) = default;
-    tuple(tuple &&) noexcept = default;
-    tuple& operator=(tuple &&) noexcept = default;
+    tuple(tuple &&) = default;
+    tuple& operator=(tuple &&) = default;
     tuple& operator=(const tuple &) = default;
 
     template <typename A, typename... As>

[wjakob]

Could the std::launder issue also be related to the use of an older libstdc++ (which is from GCC) with Clang?

[wojdyr]

Probably not, I tested Clang 7, 8 and 9 on the same system.
In abseil/abseil-cpp#1448 std::launder is reported to not work for clang < 8.

[wjakob]

I fixed compilation for Clang 8, but Clang 7 will be tricky if std::launder is broken as this code is part of a dependency. I instead bumped the Clang requirements.