[PATCH] D135045: [Frontend] Recognize environment variable SOURCE_DATE_EPOCH

Wed Oct 5 17:46:21 PDT 2022

ychen added inline comments.

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Comment at: clang/lib/Lex/PPMacroExpansion.cpp:1092
+    TT = *PP.getPreprocessorOpts().SourceDateEpoch;
+    TM = std::gmtime(&TT);
+  } else {
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MaskRay wrote:
> ychen wrote:
> > Why not use localtime as the else branch?
> > 
> > As mentioned above, diagnose null TM here or when parsing the user-specifed value. A small trade-off to make, up to you.
> Can you elaborate? With the check in Frontend I think a check here is not necessary...
Sorry I was not clear. The time_t value is not portable so it is hard to diagnose in a target-independent way. For example, `253402300799` is too big of a value for windows that `gmtime` returns null (causes crash at `asctime` in the similar case below). We could diagnose when gmtime/localtime returns null, which is portable.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D135045/new/

https://reviews.llvm.org/D135045