Implement -Wdate-time preprocessor warning

This GCC warning is useful for validating reproducible builds
and might help when tracking down issues with modules too.

llvm-svn: 210511

diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index a32b902..0ccc1de 100644 (file)
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -542,6 +542,10 @@ def err_pp_include_in_arc_cf_code_audited : Error<
 def err_pp_eof_in_arc_cf_code_audited : Error<
   "'#pragma clang arc_cf_code_audited' was not ended within this file">;
 
+def warn_pp_date_time : Warning<
+  "expansion of date or time macro is not reproducible">,
+  DefaultIgnore, InGroup<DiagGroup<"date-time">>;
+
 // Module map parsing
 def err_mmap_unknown_token : Error<"skipping stray token">;
 def err_mmap_expected_module : Error<"expected module declaration">;

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 57bc946..b22d9d4 100644 (file)
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1294,6 +1294,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
     }
     Tok.setKind(tok::string_literal);
   } else if (II == Ident__DATE__) {
+    Diag(Tok.getLocation(), diag::warn_pp_date_time);
     if (!DATELoc.isValid())
       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
     Tok.setKind(tok::string_literal);
@@ -1303,6 +1304,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
                                                  Tok.getLength()));
     return;
   } else if (II == Ident__TIME__) {
+    Diag(Tok.getLocation(), diag::warn_pp_date_time);
     if (!TIMELoc.isValid())
       ComputeDATE_TIME(DATELoc, TIMELoc, *this);
     Tok.setKind(tok::string_literal);
@@ -1327,6 +1329,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
     OS << Depth;
     Tok.setKind(tok::numeric_constant);
   } else if (II == Ident__TIMESTAMP__) {
+    Diag(Tok.getLocation(), diag::warn_pp_date_time);
     // MSVC, ICC, GCC, VisualAge C++ extension.  The generated string should be
     // of the form "Ddd Mmm dd hh::mm::ss yyyy", which is returned by asctime.
 
@@ -1347,7 +1350,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
       Result = "??? ??? ?? ??:??:?? ????\n";
     }
     // Surround the string with " and strip the trailing newline.
-    OS << '"' << StringRef(Result, strlen(Result)-1) << '"';
+    OS << '"' << StringRef(Result).drop_back() << '"';
     Tok.setKind(tok::string_literal);
   } else if (II == Ident__COUNTER__) {
     // __COUNTER__ expands to a simple numeric value.

diff --git a/clang/test/Lexer/warn-date-time.c b/clang/test/Lexer/warn-date-time.c
new file mode 100644 (file)
index 0000000..3899933
--- /dev/null
+++ b/clang/test/Lexer/warn-date-time.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -Wdate-time -Wno-builtin-macro-redefined %s -verify -E
+
+__TIME__ // expected-warning {{expansion of date or time macro is not reproducible}}
+__DATE__  // expected-warning {{expansion of date or time macro is not reproducible}}
+__TIMESTAMP__ // expected-warning {{expansion of date or time macro is not reproducible}}
+
+#define __TIME__
+__TIME__