From a8b3e29cac31317aea4c5b1fe874d527ce08ae26 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 14 Aug 2019 23:16:38 -0700
Subject: [PATCH] ircd: Apply noexcept on various constexpr callstacks.

---
 include/ircd/json/tuple/get.h     |  8 ++++++++
 include/ircd/json/tuple/indexof.h |  8 ++++++++
 include/ircd/json/tuple/key.h     |  4 ++++
 include/ircd/json/tuple/tuple.h   | 14 ++++++++++----
 include/ircd/json/util.h          |  6 ++++--
 include/ircd/string_view.h        | 22 ++++++++++++----------
 include/ircd/util/hash.h          |  9 ++++++---
 7 files changed, 52 insertions(+), 19 deletions(-)

diff --git a/include/ircd/json/tuple/get.h b/include/ircd/json/tuple/get.h
index 0532e9e9c..a92b9b3cf 100644
--- a/include/ircd/json/tuple/get.h
+++ b/include/ircd/json/tuple/get.h
@@ -18,6 +18,7 @@ template<size_t hash,
          class tuple>
 enable_if_tuple<tuple, const tuple_value_type<tuple, indexof<tuple, hash>()> &>
 get(const tuple &t)
+noexcept
 {
 	constexpr size_t idx
 	{
@@ -37,6 +38,7 @@ template<size_t hash,
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, hash>()>>
 get(const tuple &t,
     const tuple_value_type<tuple, indexof<tuple, hash>()> &def)
+noexcept
 {
 	constexpr size_t idx
 	{
@@ -55,6 +57,7 @@ template<size_t hash,
          class tuple>
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, hash>()> &>
 get(tuple &t)
+noexcept
 {
 	constexpr size_t idx
 	{
@@ -74,6 +77,7 @@ template<size_t hash,
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, hash>()> &>
 get(tuple &t,
     tuple_value_type<tuple, indexof<tuple, hash>()> &def)
+noexcept
 {
 	auto &ret
 	{
@@ -87,6 +91,7 @@ template<const char *const &name,
          class tuple>
 enable_if_tuple<tuple, const tuple_value_type<tuple, indexof<tuple, name>()> &>
 get(const tuple &t)
+noexcept
 {
 	return get<name_hash(name), tuple>(t);
 }
@@ -96,6 +101,7 @@ template<const char *const &name,
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, name>()>>
 get(const tuple &t,
     const tuple_value_type<tuple, indexof<tuple, name>()> &def)
+noexcept
 {
 	return get<name_hash(name), tuple>(t, def);
 }
@@ -104,6 +110,7 @@ template<const char *const &name,
          class tuple>
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, name>()>>
 get(tuple &t)
+noexcept
 {
 	return get<name_hash(name), tuple>(t);
 }
@@ -113,6 +120,7 @@ template<const char *const &name,
 enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, name>()>>
 get(tuple &t,
     tuple_value_type<tuple, indexof<tuple, hash>()> &def)
+noexcept
 {
 	return get<name_hash(name), tuple>(t, def);
 }
diff --git a/include/ircd/json/tuple/indexof.h b/include/ircd/json/tuple/indexof.h
index 7c04f4db4..658d700a3 100644
--- a/include/ircd/json/tuple/indexof.h
+++ b/include/ircd/json/tuple/indexof.h
@@ -19,6 +19,7 @@ template<class tuple,
          size_t i>
 constexpr typename std::enable_if<i == size<tuple>(), size_t>::type
 indexof()
+noexcept
 {
 	return size<tuple>();
 }
@@ -28,6 +29,7 @@ template<class tuple,
          size_t i = 0>
 constexpr typename std::enable_if<i < size<tuple>(), size_t>::type
 indexof()
+noexcept
 {
 	constexpr auto equal
 	{
@@ -42,6 +44,7 @@ template<class tuple,
          size_t i>
 constexpr typename std::enable_if<i == size<tuple>(), size_t>::type
 indexof()
+noexcept
 {
 	return size<tuple>();
 }
@@ -51,6 +54,7 @@ template<class tuple,
          size_t i = 0>
 constexpr typename std::enable_if<i < size<tuple>(), size_t>::type
 indexof()
+noexcept
 {
 	return indexof<tuple, name_hash(name)>();
 }
@@ -59,6 +63,7 @@ template<class tuple,
          size_t i>
 constexpr typename std::enable_if<i == size<tuple>(), size_t>::type
 indexof(const char *const &name)
+noexcept
 {
 	return size<tuple>();
 }
@@ -67,6 +72,7 @@ template<class tuple,
          size_t i = 0>
 constexpr typename std::enable_if<i < size<tuple>(), size_t>::type
 indexof(const char *const &name)
+noexcept
 {
 	constexpr auto equal
 	{
@@ -80,6 +86,7 @@ template<class tuple,
          size_t i>
 constexpr typename std::enable_if<i == size<tuple>(), size_t>::type
 indexof(const string_view &name)
+noexcept
 {
 	return size<tuple>();
 }
@@ -88,6 +95,7 @@ template<class tuple,
          size_t i = 0>
 constexpr typename std::enable_if<i < size<tuple>(), size_t>::type
 indexof(const string_view &name)
+noexcept
 {
 	const auto equal
 	{
diff --git a/include/ircd/json/tuple/key.h b/include/ircd/json/tuple/key.h
index 6846b99b0..ca91b2035 100644
--- a/include/ircd/json/tuple/key.h
+++ b/include/ircd/json/tuple/key.h
@@ -18,6 +18,7 @@ template<class tuple,
          size_t i>
 constexpr enable_if_tuple<tuple, const char *>
 key()
+noexcept
 {
 	return tuple_element<tuple, i>::key;
 }
@@ -26,6 +27,7 @@ template<class tuple,
          size_t i>
 constexpr typename std::enable_if<i == tuple::size(), const char *>::type
 key(const size_t &j)
+noexcept
 {
 	return nullptr;
 }
@@ -34,6 +36,7 @@ template<class tuple,
          size_t i = 0>
 constexpr typename std::enable_if<i < tuple::size(), const char *>::type
 key(const size_t &j)
+noexcept
 {
 	return j == i?
 		tuple_element<tuple, i>::key:
@@ -44,6 +47,7 @@ template<size_t i,
          class tuple>
 enable_if_tuple<tuple, const char *>
 key(const tuple &t)
+noexcept
 {
 	return std::get<i>(t).key;
 }
diff --git a/include/ircd/json/tuple/tuple.h b/include/ircd/json/tuple/tuple.h
index c3cd36de8..994183012 100644
--- a/include/ircd/json/tuple/tuple.h
+++ b/include/ircd/json/tuple/tuple.h
@@ -57,13 +57,13 @@ struct tuple
 	using tuple_type = std::tuple<T...>;
 	using super_type = tuple<T...>;
 
-	static constexpr size_t size();
+	static constexpr size_t size() noexcept;
 
 	operator json::value() const;
 	operator crh::sha256::buf() const;
 
-	template<class name> constexpr decltype(auto) get(name&&) const;
-	template<class name> constexpr decltype(auto) get(name&&);
+	template<class name> constexpr decltype(auto) get(name&&) const noexcept;
+	template<class name> constexpr decltype(auto) get(name&&) noexcept;
 	template<class name> constexpr decltype(auto) at(name&&) const;
 	template<class name> constexpr decltype(auto) at(name&&);
 
@@ -79,6 +79,7 @@ struct tuple
 template<class tuple>
 constexpr bool
 is_tuple()
+noexcept
 {
 	return std::is_base_of<tuple_base, tuple>::value;
 }
@@ -123,6 +124,7 @@ stdcast(tuple &o)
 template<class tuple>
 constexpr enable_if_tuple<tuple, size_t>
 size()
+noexcept
 {
 	return tuple_size<tuple>::value;
 }
@@ -140,6 +142,7 @@ template<size_t i,
          class tuple>
 enable_if_tuple<tuple, tuple_value_type<tuple, i> &>
 val(tuple &t)
+noexcept
 {
 	return static_cast<tuple_value_type<tuple, i> &>(std::get<i>(t));
 }
@@ -148,6 +151,7 @@ template<size_t i,
          class tuple>
 enable_if_tuple<tuple, const tuple_value_type<tuple, i> &>
 val(const tuple &t)
+noexcept
 {
 	return static_cast<const tuple_value_type<tuple, i> &>(std::get<i>(t));
 }
@@ -269,6 +273,7 @@ template<class... T>
 template<class name>
 constexpr decltype(auto)
 tuple<T...>::get(name&& n)
+noexcept
 {
 	constexpr const size_t hash
 	{
@@ -282,7 +287,7 @@ template<class... T>
 template<class name>
 constexpr decltype(auto)
 tuple<T...>::get(name&& n)
-const
+const noexcept
 {
 	constexpr const size_t hash
 	{
@@ -295,6 +300,7 @@ const
 template<class... T>
 constexpr size_t
 tuple<T...>::size()
+noexcept
 {
 	return std::tuple_size<tuple_type>();
 }
diff --git a/include/ircd/json/util.h b/include/ircd/json/util.h
index 94300c6f9..dbbadc8d2 100644
--- a/include/ircd/json/util.h
+++ b/include/ircd/json/util.h
@@ -21,8 +21,8 @@ namespace ircd::json
 	template<size_t SIZE> struct buffer;
 
 	using name_hash_t = size_t;
-	constexpr name_hash_t name_hash(const string_view name);
-	constexpr name_hash_t operator ""_(const char *const name, const size_t len);
+	constexpr name_hash_t name_hash(const string_view name) noexcept;
+	constexpr name_hash_t operator ""_(const char *const name, const size_t len) noexcept;
 
 	size_t serialized(const string_view &);
 	string_view stringify(mutable_buffer &, const string_view &);
@@ -79,12 +79,14 @@ ircd::json::print(const mutable_buffer &buf,
 
 constexpr ircd::json::name_hash_t
 ircd::json::operator ""_(const char *const text, const size_t len)
+noexcept
 {
 	return name_hash(string_view(text, len));
 }
 
 constexpr ircd::json::name_hash_t
 ircd::json::name_hash(const string_view name)
+noexcept
 {
 	return ircd::hash(name);
 }
diff --git a/include/ircd/string_view.h b/include/ircd/string_view.h
index 2727f4e2e..e98639afe 100644
--- a/include/ircd/string_view.h
+++ b/include/ircd/string_view.h
@@ -15,9 +15,9 @@ namespace ircd
 {
 	struct string_view;
 
-	constexpr size_t _constexpr_strlen(const char *);
-	constexpr const char *data(const string_view &);
-	constexpr size_t size(const string_view &);
+	constexpr size_t _constexpr_strlen(const char *) noexcept;
+	constexpr const char *data(const string_view &) noexcept;
+	constexpr size_t size(const string_view &) noexcept;
 	bool empty(const string_view &);
 	bool operator!(const string_view &);
 	bool defined(const string_view &);
@@ -144,7 +144,7 @@ struct ircd::string_view
 	}
 
 	// (non-standard) our iterator-based constructor
-	constexpr string_view(const char *const &begin, const char *const &end)
+	constexpr string_view(const char *const &begin, const char *const &end) noexcept
 	:string_view{begin, size_t(end - begin)}
 	{
 		assert(begin <= end);
@@ -158,7 +158,7 @@ struct ircd::string_view
 	// (non-standard) our array based constructor
 	template<size_t SIZE> constexpr
 	__attribute__((always_inline))
-	string_view(const std::array<char, SIZE> &array)
+	string_view(const std::array<char, SIZE> &array) noexcept
 	:string_view
 	{
 		array.data(), std::find(array.begin(), array.end(), '\0')
@@ -167,22 +167,21 @@ struct ircd::string_view
 	// (non-standard) our buffer based constructor
 	template<size_t SIZE> constexpr
 	__attribute__((always_inline))
-	string_view(const char (&buf)[SIZE])
+	string_view(const char (&buf)[SIZE]) noexcept
 	:string_view
 	{
 		buf, std::find(buf, buf + SIZE, '\0')
 	}{}
 
-	constexpr string_view(const char *const &start, const size_t &size)
+	constexpr string_view(const char *const &start, const size_t &size) noexcept
 	:std::string_view{start, size}
 	{}
 
-	constexpr string_view(const char *const &start)
+	constexpr string_view(const char *const &start) noexcept
 	:std::string_view{start, _constexpr_strlen(start)}
 	{}
 
-	string_view(const std::string &string)
-	noexcept
+	string_view(const std::string &string) noexcept
 	:string_view{string.data(), string.size()}
 	{}
 
@@ -257,12 +256,14 @@ ircd::defined(const string_view &str)
 
 constexpr size_t
 ircd::size(const string_view &str)
+noexcept
 {
 	return str.size();
 }
 
 constexpr const char *
 ircd::data(const string_view &str)
+noexcept
 {
 	return str.data();
 }
@@ -270,6 +271,7 @@ ircd::data(const string_view &str)
 [[gnu::pure]]
 constexpr size_t
 ircd::_constexpr_strlen(const char *const s)
+noexcept
 {
 	const char *e(s);
 	if(e) for(; *e; ++e);
diff --git a/include/ircd/util/hash.h b/include/ircd/util/hash.h
index fb79ddaf0..3b24e610b 100644
--- a/include/ircd/util/hash.h
+++ b/include/ircd/util/hash.h
@@ -17,12 +17,12 @@ inline namespace util
 	// constexpr bernstein string hasher suite; these functions will hash the
 	// string at compile time leaving an integer residue at runtime. Decent
 	// primes are at least 7681 and 5381.
-	template<size_t PRIME = 7681> constexpr size_t hash(const char16_t *const str, const size_t i = 0);
-	template<size_t PRIME = 7681> constexpr size_t hash(const string_view str, const size_t i = 0);
+	template<size_t PRIME = 7681> constexpr size_t hash(const char16_t *const str, const size_t i = 0) noexcept;
+	template<size_t PRIME = 7681> constexpr size_t hash(const string_view str, const size_t i = 0) noexcept;
 
 	// Note that at runtime this hash uses multiplication on every character
 	// which can consume many cycles...
-	template<size_t PRIME = 7681> size_t hash(const std::u16string &str, const size_t i = 0);
+	template<size_t PRIME = 7681> size_t hash(const std::u16string &str, const size_t i = 0) noexcept;
 }}
 
 /// Runtime hashing of a std::u16string (for js). Non-cryptographic.
@@ -31,6 +31,7 @@ template<size_t PRIME>
 size_t
 ircd::util::hash(const std::u16string &str,
                  const size_t i)
+noexcept
 {
 	return i >= str.size()? PRIME : (hash(str, i+1) * 33ULL) ^ str.at(i);
 }
@@ -41,6 +42,7 @@ template<size_t PRIME>
 constexpr size_t
 ircd::util::hash(const string_view str,
                  const size_t i)
+noexcept
 {
 	return i >= str.size()? PRIME : (hash(str, i+1) * 33ULL) ^ str.at(i);
 }
@@ -51,6 +53,7 @@ template<size_t PRIME>
 constexpr size_t
 ircd::util::hash(const char16_t *const str,
                  const size_t i)
+noexcept
 {
 	return !str[i]? PRIME : (hash(str, i+1) * 33ULL) ^ str[i];
 }