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

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.

Differential Revision: https://reviews.llvm.org/D136717

2 files changed, 11 insertions, 2 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index d1e5ad3..1ebb37e 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1462,6 +1462,11 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
 
   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.
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index bcd5359..9cd6d86 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4227,6 +4227,9 @@ static void GeneratePreprocessorArgs(PreprocessorOptions &Opts,
   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.
 }
@@ -4309,14 +4312,15 @@ static bool ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
     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 {