ADT: Use LLVM_NODISCARD instead of LLVM_ATTRIBUTE_UNUSED_RESULT for S…

…tringRef

Instead of annotating (most of) the StringRef API, we can just
annotate the type directly. This is less code and it will warn in more
cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284364 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/StringRef.h

@@ -44,7 +44,7 @@ namespace llvm {
   /// situations where the character data resides in some other buffer, whose
   /// lifetime extends past that of the StringRef. For this reason, it is not in
   /// general safe to store a StringRef.
-  class StringRef {
+  class LLVM_NODISCARD StringRef {
   public:
     typedef const char *iterator;
     typedef const char *const_iterator;
@@ -281,8 +281,8 @@ namespace llvm {
     ///
     /// \returns The index of the first character satisfying \p F starting from
     /// \p From, or npos if not found.
+    LLVM_NODISCARD
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     size_t find_if(function_ref<bool(char)> F, size_t From = 0) const {
       StringRef S = drop_front(From);
       while (!S.empty()) {
@@ -297,8 +297,8 @@ namespace llvm {
     ///
     /// \returns The index of the first character not satisfying \p F starting
     /// from \p From, or npos if not found.
+    LLVM_NODISCARD
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     size_t find_if_not(function_ref<bool(char)> F, size_t From = 0) const {
       return find_if([F](char c) { return !F(c); }, From);
     }
@@ -500,7 +500,6 @@ namespace llvm {
     /// exceeds the number of characters remaining in the string, the string
     /// suffix (starting with \p Start) will be returned.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef substr(size_t Start, size_t N = npos) const {
       Start = std::min(Start, Length);
       return StringRef(Data + Start, std::min(N, Length - Start));
@@ -510,7 +509,6 @@ namespace llvm {
     /// elements remaining.  If \p N is greater than the length of the
     /// string, the entire string is returned.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef take_front(size_t N = 1) const {
       if (N >= size())
         return *this;
@@ -521,7 +519,6 @@ namespace llvm {
     /// elements remaining.  If \p N is greater than the length of the
     /// string, the entire string is returned.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef take_back(size_t N = 1) const {
       if (N >= size())
         return *this;
@@ -531,23 +528,20 @@ namespace llvm {
     /// Return the longest prefix of 'this' such that every character
     /// in the prefix satisfies the given predicate.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef take_while(function_ref<bool(char)> F) const {
       return substr(0, find_if_not(F));
     }
 
     /// Return the longest prefix of 'this' such that no character in
     /// the prefix satisfies the given predicate.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef take_until(function_ref<bool(char)> F) const {
       return substr(0, find_if(F));
     }
 
     /// Return a StringRef equal to 'this' but with the first \p N elements
     /// dropped.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef drop_front(size_t N = 1) const {
       assert(size() >= N && "Dropping more elements than exist");
       return substr(N);
@@ -556,7 +550,6 @@ namespace llvm {
     /// Return a StringRef equal to 'this' but with the last \p N elements
     /// dropped.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef drop_back(size_t N = 1) const {
       assert(size() >= N && "Dropping more elements than exist");
       return substr(0, size()-N);
@@ -565,23 +558,21 @@ namespace llvm {
     /// Return a StringRef equal to 'this', but with all characters satisfying
     /// the given predicate dropped from the beginning of the string.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef drop_while(function_ref<bool(char)> F) const {
       return substr(find_if_not(F));
     }
 
     /// Return a StringRef equal to 'this', but with all characters not
     /// satisfying the given predicate dropped from the beginning of the string.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef drop_until(function_ref<bool(char)> F) const {
       return substr(find_if(F));
     }
 
     /// Returns true if this StringRef has the given prefix and removes that
     /// prefix.
+    LLVM_NODISCARD
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     bool consume_front(StringRef Prefix) {
       if (!startswith(Prefix))
         return false;
@@ -592,8 +583,8 @@ namespace llvm {
 
     /// Returns true if this StringRef has the given suffix and removes that
     /// suffix.
+    LLVM_NODISCARD
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     bool consume_back(StringRef Suffix) {
       if (!endswith(Suffix))
         return false;
@@ -614,7 +605,6 @@ namespace llvm {
     /// will be returned. If this is less than \p Start, an empty string will
     /// be returned.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef slice(size_t Start, size_t End) const {
       Start = std::min(Start, Length);
       End = std::min(std::max(Start, End), Length);
@@ -709,42 +699,36 @@ namespace llvm {
 
     /// Return string with consecutive \p Char characters starting from the
     /// the left removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef ltrim(char Char) const {
       return drop_front(std::min(Length, find_first_not_of(Char)));
     }
 
     /// Return string with consecutive characters in \p Chars starting from
     /// the left removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef ltrim(StringRef Chars = " \t\n\v\f\r") const {
       return drop_front(std::min(Length, find_first_not_of(Chars)));
     }
 
     /// Return string with consecutive \p Char characters starting from the
     /// right removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef rtrim(char Char) const {
       return drop_back(Length - std::min(Length, find_last_not_of(Char) + 1));
     }
 
     /// Return string with consecutive characters in \p Chars starting from
     /// the right removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef rtrim(StringRef Chars = " \t\n\v\f\r") const {
       return drop_back(Length - std::min(Length, find_last_not_of(Chars) + 1));
     }
 
     /// Return string with consecutive \p Char characters starting from the
     /// left and right removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef trim(char Char) const {
       return ltrim(Char).rtrim(Char);
     }
 
     /// Return string with consecutive characters in \p Chars starting from
     /// the left and right removed.
-    LLVM_ATTRIBUTE_UNUSED_RESULT
     StringRef trim(StringRef Chars = " \t\n\v\f\r") const {
       return ltrim(Chars).rtrim(Chars);
     }