thakis created this revision.
thakis added a reviewer: rsmith.
thakis added a subscriber: cfe-commits.
This is useful for creating reproducible builds. Defining these via -D triggers
warnings, and can cause bugs (presently, e.g. PR29119). It makes it also
impossible to override __DATE__ and __TIME__ and forget __TIMESTAMP__.
__TIMESTAMP__ has slightly different semantics in that it's the timestamp of
the current TU, not the time of compilation, but either meaning is bad for
reproducible builds.
https://reviews.llvm.org/D23934
Files:
include/clang/Driver/Options.td
include/clang/Lex/PreprocessorOptions.h
lib/Driver/Tools.cpp
lib/Frontend/CompilerInvocation.cpp
lib/Lex/PPMacroExpansion.cpp
test/Preprocessor/fixed-date-time.cc
Index: test/Preprocessor/fixed-date-time.cc
===================================================================
--- test/Preprocessor/fixed-date-time.cc
+++ test/Preprocessor/fixed-date-time.cc
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -ffixed-date-time=2008-09-02T14:30:27 -std=c++11 %s -verify
+// RUN: not %clang_cc1 -ffixed-date-time=2008-09-02T14:30:27asdf -std=c++11 %s 2>&1 | FileCheck %s
+// expected-no-diagnostics
+
+// CHECK: error: invalid value '2008-09-02T14:30:27asdf' in '-ffixed-date-time=2008-09-02T14:30:27asdf'
+
+constexpr int constexpr_strcmp(const char *p, const char *q) {
+ return *p != *q ? *p - *q : !*p ? 0 : constexpr_strcmp(p + 1, q + 1);
+}
+
+static_assert(!constexpr_strcmp(__DATE__, "Sep 2 2008"), "");
+static_assert(!constexpr_strcmp(__TIME__, "14:30:27"), "");
+static_assert(!constexpr_strcmp(__TIMESTAMP__, "Tue Sep 2 14:30:27 2008"), "");
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -785,6 +785,9 @@
def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Generate calls to instrument function entry and exit">;
+def ffixed_date_time_EQ : Joined<["-"], "ffixed-date-time=">, Group<f_Group>,
+ Flags<[CC1Option, CoreOption]>,
+ HelpText<"Set a fixed value for __DATE__, __TIME__, __TIMESTAMP__, formatted as 1969-12-31T23:59:59 (RFC3339 without fractional seconds and timezone)">;
def fxray_instrument : Flag<["-"], "fxray-instrument">, Group<f_Group>,
Flags<[CC1Option]>,
Index: include/clang/Lex/PreprocessorOptions.h
===================================================================
--- include/clang/Lex/PreprocessorOptions.h
+++ include/clang/Lex/PreprocessorOptions.h
@@ -12,11 +12,13 @@
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSet.h"
#include <cassert>
#include <set>
#include <string>
+#include <ctime>
#include <utility>
#include <vector>
@@ -138,6 +140,9 @@
/// build it again.
IntrusiveRefCntPtr<FailedModulesSet> FailedModules;
+ /// If set, a fixed time that __DATE__, __TIME__, __TIMESTAMP__ expand to.
+ llvm::Optional<tm> FixedDateTime;
+
public:
PreprocessorOptions() : UsePredefines(true), DetailedRecord(false),
DisablePCHValidation(false),
Index: lib/Lex/PPMacroExpansion.cpp
===================================================================
--- lib/Lex/PPMacroExpansion.cpp
+++ lib/Lex/PPMacroExpansion.cpp
@@ -21,6 +21,7 @@
#include "clang/Lex/MacroArgs.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringSwitch.h"
@@ -1012,8 +1013,14 @@
/// the identifier tokens inserted.
static void ComputeDATE_TIME(SourceLocation &DATELoc, SourceLocation &TIMELoc,
Preprocessor &PP) {
- time_t TT = time(nullptr);
- struct tm *TM = localtime(&TT);
+ struct tm *TM;
+ PreprocessorOptions &PO = PP.getPreprocessorOpts();
+ if (PO.FixedDateTime.hasValue())
+ TM = PO.FixedDateTime.getPointer();
+ else {
+ time_t TT = time(nullptr);
+ TM = localtime(&TT);
+ }
static const char * const Months[] = {
"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
@@ -1644,21 +1651,26 @@
// 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.
- // Get the file that we are lexing out of. If we're currently lexing from
- // a macro, dig into the include stack.
- const FileEntry *CurFile = nullptr;
- PreprocessorLexer *TheLexer = getCurrentFileLexer();
-
- if (TheLexer)
- CurFile = SourceMgr.getFileEntryForID(TheLexer->getFileID());
-
const char *Result;
- if (CurFile) {
- time_t TT = CurFile->getModificationTime();
- struct tm *TM = localtime(&TT);
- Result = asctime(TM);
+ PreprocessorOptions &PO = getPreprocessorOpts();
+ if (PO.FixedDateTime.hasValue()) {
+ Result = asctime(PO.FixedDateTime.getPointer());
} else {
- Result = "??? ??? ?? ??:??:?? ????\n";
+ // Get the file that we are lexing out of. If we're currently lexing from
+ // a macro, dig into the include stack.
+ const FileEntry *CurFile = nullptr;
+ PreprocessorLexer *TheLexer = getCurrentFileLexer();
+
+ if (TheLexer)
+ CurFile = SourceMgr.getFileEntryForID(TheLexer->getFileID());
+
+ if (CurFile) {
+ time_t TT = CurFile->getModificationTime();
+ struct tm *TM = localtime(&TT);
+ Result = asctime(TM);
+ } else {
+ Result = "??? ??? ?? ??:??:?? ????\n";
+ }
}
// Surround the string with " and strip the trailing newline.
OS << '"' << StringRef(Result).drop_back() << '"';
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -44,6 +44,7 @@
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/ScopedPrinter.h"
#include <atomic>
+#include <ctime>
#include <memory>
#include <sys/stat.h>
#include <system_error>
@@ -2237,6 +2238,21 @@
else
Opts.ObjCXXARCStandardLibrary = (ObjCXXARCStandardLibraryKind)Library;
}
+
+ if (Arg *A = Args.getLastArg(OPT_ffixed_date_time_EQ)) {
+ StringRef DateTime = A->getValue();
+ tm TM = {};
+ char *Rest = strptime(DateTime.str().c_str(), "%Y-%m-%dT%T", &TM);
+ if (!Rest || *Rest)
+ Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args)
+ << DateTime;
+ else {
+ // Fill in tm_wday.
+ TM.tm_isdst = -1;
+ mktime(&TM);
+ Opts.FixedDateTime = TM;
+ }
+ }
}
static void ParsePreprocessorOutputArgs(PreprocessorOutputOptions &Opts,
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -4681,6 +4681,11 @@
CmdArgs.push_back("-generate-type-units");
}
+ if (Arg *A = Args.getLastArg(options::OPT_ffixed_date_time_EQ)) {
+ StringRef DateTime = A->getValue();
+ CmdArgs.push_back(Args.MakeArgString("-ffixed-date-time=" + DateTime));
+ }
+
// CloudABI and WebAssembly use -ffunction-sections and -fdata-sections by
// default.
bool UseSeparateSections = Triple.getOS() == llvm::Triple::CloudABI ||
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