From 5eb79c2303d162a44c64b5b35148d19a63959418 Mon Sep 17 00:00:00 2001
From: Vitaly Baranov <vitbar@yandex-team.ru>
Date: Sun, 15 Mar 2020 16:52:46 +0300
Subject: [PATCH] Cast "const char *" to StringRef is now implicit and
 constexpr.

---
 base/common/StringRef.h           | 10 +++++-----
 dbms/src/IO/WriteHelpers.h        |  5 -----
 dbms/src/Interpreters/Context.cpp |  4 ++--
 dbms/src/Interpreters/Context.h   |  4 ++--
 4 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/base/common/StringRef.h b/base/common/StringRef.h
index 961aab58980..076b8982b1d 100644
--- a/base/common/StringRef.h
+++ b/base/common/StringRef.h
@@ -27,17 +27,17 @@ struct StringRef
     size_t size = 0;
 
     template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
-    StringRef(const CharT * data_, size_t size_) : data(reinterpret_cast<const char *>(data_)), size(size_) {}
+    constexpr StringRef(const CharT * data_, size_t size_) : data(reinterpret_cast<const char *>(data_)), size(size_) {}
 
     StringRef(const std::string & s) : data(s.data()), size(s.size()) {}
-    StringRef(const std::string_view & s) : data(s.data()), size(s.size()) {}
-    explicit StringRef(const char * data_) : data(data_), size(strlen(data_)) {}
-    StringRef() = default;
+    constexpr StringRef(const std::string_view & s) : data(s.data()), size(s.size()) {}
+    constexpr StringRef(const char * data_) : StringRef(std::string_view{data_}) {}
+    constexpr StringRef() = default;
 
     std::string toString() const { return std::string(data, size); }
 
     explicit operator std::string() const { return toString(); }
-    explicit operator std::string_view() const { return {data, size}; }
+    constexpr explicit operator std::string_view() const { return {data, size}; }
 };
 
 using StringRefs = std::vector<StringRef>;
diff --git a/dbms/src/IO/WriteHelpers.h b/dbms/src/IO/WriteHelpers.h
index 44b0322ee83..10918fb7b61 100644
--- a/dbms/src/IO/WriteHelpers.h
+++ b/dbms/src/IO/WriteHelpers.h
@@ -239,11 +239,6 @@ inline void writeFloatText(T x, WriteBuffer & buf)
 }
 
 
-inline void writeString(const String & s, WriteBuffer & buf)
-{
-    buf.write(s.data(), s.size());
-}
-
 inline void writeString(const char * data, size_t size, WriteBuffer & buf)
 {
     buf.write(data, size);
diff --git a/dbms/src/Interpreters/Context.cpp b/dbms/src/Interpreters/Context.cpp
index ab9b4a2c31b..ef45fd60e81 100644
--- a/dbms/src/Interpreters/Context.cpp
+++ b/dbms/src/Interpreters/Context.cpp
@@ -947,7 +947,7 @@ void Context::setSettings(const Settings & settings_)
 }
 
 
-void Context::setSetting(const String & name, const String & value)
+void Context::setSetting(const StringRef & name, const String & value)
 {
     auto lock = getLock();
     if (name == "profile")
@@ -962,7 +962,7 @@ void Context::setSetting(const String & name, const String & value)
 }
 
 
-void Context::setSetting(const String & name, const Field & value)
+void Context::setSetting(const StringRef & name, const Field & value)
 {
     auto lock = getLock();
     if (name == "profile")
diff --git a/dbms/src/Interpreters/Context.h b/dbms/src/Interpreters/Context.h
index 5d8351ed598..2f049d14cd3 100644
--- a/dbms/src/Interpreters/Context.h
+++ b/dbms/src/Interpreters/Context.h
@@ -344,8 +344,8 @@ public:
     void setSettings(const Settings & settings_);
 
     /// Set settings by name.
-    void setSetting(const String & name, const String & value);
-    void setSetting(const String & name, const Field & value);
+    void setSetting(const StringRef & name, const String & value);
+    void setSetting(const StringRef & name, const Field & value);
     void applySettingChange(const SettingChange & change);
     void applySettingsChanges(const SettingsChanges & changes);