util/StringView: use [[gnu::]] attributes

src/util/StringView.hxx

 /*
- * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2021 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -103,12 +103,12 @@ struct BasicStringView : ConstBuffer<T> {
 		return {start, size_t(data + size - start)};
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	pointer Find(value_type ch) const noexcept {
 		return StringFind(data, ch, this->size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	pointer FindLast(value_type ch) const noexcept {
 		return StringFindLast(data, ch, size);
 	}
@@ -118,7 +118,7 @@ struct BasicStringView : ConstBuffer<T> {
 	 * character.  If the character is not found, then the first
 	 * value is the whole string and the second value is nullptr.
 	 */
-	gcc_pure
+	[[gnu::pure]]
 	std::pair<BasicStringView<T>, BasicStringView<T>> Split(value_type ch) const noexcept {
 		const auto separator = Find(ch);
 		if (separator == nullptr)
@@ -132,7 +132,7 @@ struct BasicStringView : ConstBuffer<T> {
 	 * character.  If the character is not found, then the first
 	 * value is the whole string and the second value is nullptr.
 	 */
-	gcc_pure
+	[[gnu::pure]]
 	std::pair<BasicStringView<T>, BasicStringView<T>> SplitLast(value_type ch) const noexcept {
 		const auto separator = FindLast(ch);
 		if (separator == nullptr)
@@ -141,30 +141,30 @@ struct BasicStringView : ConstBuffer<T> {
 		return {{begin(), separator}, {separator + 1, end()}};
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool StartsWith(BasicStringView<T> needle) const noexcept {
 		return this->size >= needle.size &&
 			StringIsEqual(data, needle.data, needle.size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool EndsWith(BasicStringView<T> needle) const noexcept {
 		return this->size >= needle.size &&
 			StringIsEqual(data + this->size - needle.size,
 				      needle.data, needle.size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool StartsWith(value_type ch) const noexcept {
 		return !empty() && front() == ch;
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool EndsWith(value_type ch) const noexcept {
 		return !empty() && back() == ch;
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	int Compare(BasicStringView<T> other) const noexcept {
 		if (size < other.size) {
 			int result = StringCompare(data, other.data, size);
@@ -181,26 +181,26 @@ struct BasicStringView : ConstBuffer<T> {
 			return StringCompare(data, other.data, size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool Equals(BasicStringView<T> other) const noexcept {
 		return this->size == other.size &&
 			StringIsEqual(data, other.data, this->size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool StartsWithIgnoreCase(BasicStringView<T> needle) const noexcept {
 		return this->size >= needle.size &&
 			StringIsEqualIgnoreCase(data, needle.data, needle.size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool EndsWithIgnoreCase(BasicStringView<T> needle) const noexcept {
 		return this->size >= needle.size &&
 			StringIsEqualIgnoreCase(data + this->size - needle.size,
 						needle.data, needle.size);
 	}
 
-	gcc_pure
+	[[gnu::pure]]
 	bool EqualsIgnoreCase(BasicStringView<T> other) const noexcept {
 		return this->size == other.size &&
 			StringIsEqualIgnoreCase(data, other.data, this->size);

src/util/WStringView.hxx

 /*
- * Copyright (C) 2013-2017 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2021 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions