[clang] Move getenv call for SOURCE_DATE_EPOCH out of frontend NFC

[benlangmuir]

Summary

Move the check for SOURCE_DATE_EPOCH to the driver and use a cc1 option to pass it to the frontend. This avoids hidden state in the cc1 invocation and makes this env variable behave more like other env variables that clang handles in the driver.

[MaskRay]

clang/lib/Frontend/CompilerInvocation.cpp

4324

Is it worth making err_fe_invalid_source_date_epoch a driver diagnostic? I think driver validation is more common.

clang/test/Driver/SOURCE_DATE_EPOCH.c

3

In case someone put the build directory under a directory with the string -source-date-epoch, even if it is highly unlikely.

[benlangmuir]

clang/lib/Frontend/CompilerInvocation.cpp

4324

I wasn't sure if we could just move the validation to the driver or if we would end up duplicating it -- how bad is it to have a value that's too large? If it could cause UB or something I wouldn't want to remove the check from the frontend.

[steven_wu]

LGTM

[benlangmuir]

clang/lib/Frontend/CompilerInvocation.cpp

4324

I kept the validation in the frontend for now but happy to iterate on this if you'd like.

clang/test/Driver/SOURCE_DATE_EPOCH.c

3

Fair point, done!

[tstellar]

clang/test/Driver/SOURCE_DATE_EPOCH.c

2

Hi @benlangmuir, this test fails in our build environment, because we have the SOURCE_DATE_EPOCH env variable set globally. Is there any way to update the test to handle this scenario?

[benlangmuir]

clang/test/Driver/SOURCE_DATE_EPOCH.c

2

I'm not aware of a portable way to unset environment variables (env -u doesn't work on some of our platforms) and this first check is low-value anyway, so I'm fine with just dropping it and only having the ones below that explicitly set a value. https://reviews.llvm.org/D142511

clang/include/clang/Driver/Options.td

def detailed_preprocessing_record : Flag<["-"], "detailed-preprocessing-record">,
   HelpText<"include a detailed record of preprocessing actions">,
   MarshallingInfoFlag<PreprocessorOpts<"DetailedRecord">>;
 def setup_static_analyzer : Flag<["-"], "setup-static-analyzer">,
   HelpText<"Set up preprocessor for static analyzer (done automatically when static analyzer is run).">,
   MarshallingInfoFlag<PreprocessorOpts<"SetUpStaticAnalyzer">>;
 def disable_pragma_debug_crash : Flag<["-"], "disable-pragma-debug-crash">,
   HelpText<"Disable any #pragma clang __debug that can lead to crashing behavior. This is meant for testing.">,
   MarshallingInfoFlag<PreprocessorOpts<"DisablePragmaDebugCrash">>;
+def source_date_epoch : Separate<["-"], "source-date-epoch">,
+  MetaVarName<"<time since Epoch in seconds>">,
+  HelpText<"Time to be used in __DATE__, __TIME__, and __TIMESTAMP__ macros">;
 
 } // let Flags = [CC1Option, NoDriverOption]
 
 //===----------------------------------------------------------------------===//
 // CUDA Options
 //===----------------------------------------------------------------------===//
 
 let Flags = [CC1Option, NoDriverOption] in {

clang/lib/Driver/ToolChains/Clang.cpp

else {
     getToolChain().AddIAMCUIncludeArgs(Args, CmdArgs);
   }
 
   addMacroPrefixMapArg(D, Args, CmdArgs);
   addCoveragePrefixMapArg(D, Args, CmdArgs);
 
   Args.AddLastArg(CmdArgs, options::OPT_ffile_reproducible,
                   options::OPT_fno_file_reproducible);
+
+  if (const char *Epoch = std::getenv("SOURCE_DATE_EPOCH")) {
+    CmdArgs.push_back("-source-date-epoch");
+    CmdArgs.push_back(Args.MakeArgString(Epoch));
+  }
 }
 
 // FIXME: Move to target hook.
 static bool isSignedCharDefault(const llvm::Triple &Triple) {
   switch (Triple.getArch()) {
   default:
     return true;
 

clang/lib/Frontend/CompilerInvocation.cpp

#undef PREPROCESSOR_OPTION_WITH_MARSHALLING
   }
 
   for (const auto &CI : Opts.ChainedIncludes)
     GenerateArg(Args, OPT_chain_include, CI, SA);
 
   for (const auto &RF : Opts.RemappedFiles)
     GenerateArg(Args, OPT_remap_file, RF.first + ";" + RF.second, SA);
 
+  if (Opts.SourceDateEpoch)
+    GenerateArg(Args, OPT_source_date_epoch, Twine(*Opts.SourceDateEpoch), SA);
+
   // Don't handle LexEditorPlaceholders. It is implied by the action that is
   // generated elsewhere.
 }
 
 static bool ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
                                   DiagnosticsEngine &Diags,
                                   frontend::ActionKind Action,
                                   const FrontendOptions &FrontendOpts) {
for (const auto *A : Args.filtered(OPT_remap_file)) {
     if (Split.second.empty()) {
       Diags.Report(diag::err_drv_invalid_remap_file) << A->getAsString(Args);
       continue;
     }
 
     Opts.addRemappedFile(Split.first, Split.second);
   }
 
-  if (const char *Epoch = std::getenv("SOURCE_DATE_EPOCH")) {
+  if (const Arg *A = Args.getLastArg(OPT_source_date_epoch)) {
+    StringRef Epoch = A->getValue();
     // SOURCE_DATE_EPOCH, if specified, must be a non-negative decimal integer.
     // On time64 systems, pick 253402300799 (the UNIX timestamp of
     // 9999-12-31T23:59:59Z) as the upper bound.
     const uint64_t MaxTimestamp =
         std::min<uint64_t>(std::numeric_limits<time_t>::max(), 253402300799);
     uint64_t V;
-    if (StringRef(Epoch).getAsInteger(10, V) || V > MaxTimestamp) {
+    if (Epoch.getAsInteger(10, V) || V > MaxTimestamp) {
       Diags.Report(diag::err_fe_invalid_source_date_epoch)
           << Epoch << MaxTimestamp;
     } else {
       Opts.SourceDateEpoch = V;
     }
   }
 
   // Always avoid lexing editor placeholders when we're just running the
   // preprocessor as we never want to emit the

clang/test/Driver/SOURCE_DATE_EPOCH.c

+// RUN: %clang -E %s -### 2>&1 | FileCheck %s -check-prefix=NO_EPOCH
+// NO_EPOCH-NOT: "-source-date-epoch"
+
+// RUN: env SOURCE_DATE_EPOCH=123 %clang -E %s -### 2>&1 | FileCheck %s
+// CHECK: "-source-date-epoch" "123"

clang/test/Preprocessor/SOURCE_DATE_EPOCH.c

-// RUN: env SOURCE_DATE_EPOCH=0 %clang_cc1 -E %s | FileCheck %s --check-prefix=19700101
+// RUN: %clang_cc1 -source-date-epoch 0 -E %s | FileCheck %s --check-prefix=19700101
 
 // 19700101:      const char date[] = "Jan  1 1970";
 // 19700101-NEXT: const char time[] = "00:00:00";
 // 19700101-NEXT: const char timestamp[] = "Thu Jan  1 00:00:00 1970";
 
-// RUN: env SOURCE_DATE_EPOCH=2147483647 %clang_cc1 -E -Wdate-time %s 2>&1 | FileCheck %s --check-prefix=Y2038
+// RUN: %clang_cc1 -source-date-epoch 2147483647 -E -Wdate-time %s 2>&1 | FileCheck %s --check-prefix=Y2038
 
 // Y2038:      warning: expansion of date or time macro is not reproducible [-Wdate-time]
 // Y2038:      const char date[] = "Jan 19 2038";
 // Y2038-NEXT: const char time[] = "03:14:07";
 // Y2038-NEXT: const char timestamp[] = "Tue Jan 19 03:14:07 2038";
 
 /// Test a large timestamp if the system uses 64-bit time_t and known to support large timestamps.
-// RUN: %if !system-windows && clang-target-64-bits %{ env SOURCE_DATE_EPOCH=253402300799 %clang_cc1 -E -Wdate-time %s 2>&1 | FileCheck %s --check-prefix=99991231 %}
+// RUN: %if !system-windows && clang-target-64-bits %{ %clang_cc1 -source-date-epoch 253402300799 -E -Wdate-time %s 2>&1 | FileCheck %s --check-prefix=99991231 %}
 
 // 99991231:      warning: expansion of date or time macro is not reproducible [-Wdate-time]
 // 99991231:      const char date[] = "Dec 31 9999";
 // 99991231-NEXT: const char time[] = "23:59:59";
 // 99991231-NEXT: const char timestamp[] = "Fri Dec 31 23:59:59 9999";
 
-// RUN: env SOURCE_DATE_EPOCH=253402300800 not %clang_cc1 -E %s 2>&1 | FileCheck %s --check-prefix=TOOBIG
+// RUN: not %clang_cc1 -source-date-epoch 253402300800 -E %s 2>&1 | FileCheck %s --check-prefix=TOOBIG
 
 // TOOBIG: error: environment variable 'SOURCE_DATE_EPOCH' ('253402300800') must be a non-negative decimal integer <= {{(2147483647|253402300799)}}
 
-// RUN: env SOURCE_DATE_EPOCH=0x0 not %clang_cc1 -E %s 2>&1 | FileCheck %s --check-prefix=NOTDECIMAL
+// RUN: not %clang_cc1 -source-date-epoch 0x0 -E %s 2>&1 | FileCheck %s --check-prefix=NOTDECIMAL
 
 // NOTDECIMAL: error: environment variable 'SOURCE_DATE_EPOCH' ('0x0') must be a non-negative decimal integer <= {{(2147483647|253402300799)}}
 
 const char date[] = __DATE__;
 const char time[] = __TIME__;
 const char timestamp[] = __TIMESTAMP__;