[PATCH] D49504: Enable C++2a Chrono Literals

[Erich Keane via Phabricator via cfe-commits]

erichkeane created this revision.
erichkeane added reviewers: rsmith, gribozavr, ddunbar, eli.friedman.
Herald added a subscriber: cfe-commits.

C++2a via http://wg21.link/p0355 permits the library
literals of 'd' and 'y'.  This patch enables them in the
Lexer so that they can be properly parsed.

Note that 'd' gets confused with the hex character, so 
modifications to how octal, binary, and decimal numbers are
parsed were required. Since this is simply making previously 
invalid code legal, this should be fine.

Hex still greedily parses the 'd' as a hexit, since it would 
a: violate [lex.ext]p1
b: break existing code.


Repository:
  rC Clang

https://reviews.llvm.org/D49504

Files:
  lib/Lex/LiteralSupport.cpp
  test/SemaCXX/cxx2a-user-defined-literals.cpp


Index: lib/Lex/LiteralSupport.cpp
===================================================================
--- lib/Lex/LiteralSupport.cpp
+++ lib/Lex/LiteralSupport.cpp
@@ -751,7 +751,8 @@
 
   // If we have a hex digit other than 'e' (which denotes a FP exponent) then
   // the code is using an incorrect base.
-  if (isHexDigit(*s) && *s != 'e' && *s != 'E') {
+  if (isHexDigit(*s) && *s != 'e' && *s != 'E' &&
+      !isValidUDSuffix(PP.getLangOpts(), StringRef(s, ThisTokEnd - s))) {
     PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s-ThisTokBegin),
             diag::err_invalid_digit) << StringRef(s, 1) << (radix == 8 ? 1 : 0);
     hadError = true;
@@ -804,12 +805,14 @@
   if (!LangOpts.CPlusPlus14)
     return false;
 
-  // In C++1y, "s", "h", "min", "ms", "us", and "ns" are used in the library.
+  // In C++14, "s", "h", "min", "ms", "us", and "ns" are used in the library.
   // Per tweaked N3660, "il", "i", and "if" are also used in the library.
+  // In C++2a "d" and "y" are used in the library.
   return llvm::StringSwitch<bool>(Suffix)
       .Cases("h", "min", "s", true)
       .Cases("ms", "us", "ns", true)
       .Cases("il", "i", "if", true)
+      .Cases("d", "y", LangOpts.CPlusPlus2a)
       .Default(false);
 }
 
@@ -922,7 +925,9 @@
     s = SkipBinaryDigits(s);
     if (s == ThisTokEnd) {
       // Done.
-    } else if (isHexDigit(*s)) {
+    } else if (isHexDigit(*s) &&
+               !isValidUDSuffix(PP.getLangOpts(),
+                                StringRef(s, ThisTokEnd - s))) {
       PP.Diag(PP.AdvanceToTokenCharacter(TokLoc, s-ThisTokBegin),
               diag::err_invalid_digit) << StringRef(s, 1) << 2;
       hadError = true;
Index: test/SemaCXX/cxx2a-user-defined-literals.cpp
===================================================================
--- test/SemaCXX/cxx2a-user-defined-literals.cpp
+++ test/SemaCXX/cxx2a-user-defined-literals.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 -std=c++2a %s -include %s -verify
+
+#ifndef INCLUDED
+#define INCLUDED
+
+#pragma clang system_header
+namespace std {
+  struct string {};
+  namespace chrono {
+    struct day{};
+    struct year{};
+  }
+  using size_t = decltype(sizeof(0));
+  constexpr chrono::day operator"" d(unsigned long long d) noexcept;
+  constexpr chrono::year operator"" y(unsigned long long y) noexcept;
+}
+
+#else
+
+using namespace std;
+chrono::day dec_d = 5d;
+chrono::day oct_d = 05d;
+chrono::day bin_d = 0b011d;
+// expected-error at +3{{no viable conversion from 'int' to 'chrono::day'}}
+// expected-note at 11{{candidate constructor (the implicit copy constructor)}}
+// expected-note at 11{{candidate constructor (the implicit move constructor)}}
+chrono::day hex_d = 0x44d;
+chrono::year y  = 10y;
+#endif


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