[PATCH] D86069: [clang] When loading preamble from AST file, re-export modules in Sema.

[Adam Czachorowski via Phabricator via cfe-commits]

adamcz added inline comments.


================
Comment at: clang/test/PCH/preamble-modules.cpp:8
+
+#ifndef MAIN_FILE
+#define MAIN_FILE
----------------
sammccall wrote:
> what are these ifdefs about? you never seem to define this symbol
> 
> (Possible you're copying from a test that is doing something tricky like being run in two modes or including itself? Or did you mean to give different flags for the include vs emit pch?)
Oh, I stole this trick from Kadir. You compile this file twice. First one is to generate a PCH for preamble. MAIN_FILE is not set, so it only reads the preamble section. The second one has -include-pch. That means MAIN_FILE is now set (from the preamble PCH file), so we only compile the main section.

It's a creative solution to a problem I wish I didn't have ;-)
Is there a better way to do this, without splitting the file in two? preamble_bytes seems fragile.


================
Comment at: clang/test/PCH/preamble-modules.cpp:14
+// Main section.
+MyType foo;
+#endif
----------------
sammccall wrote:
> This seems like currently it's never getting parsed as MAIN_FILE is never defined.
It's parsed. Without this fix, there's a warning generated here. See comment above for explanation.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D86069/new/

https://reviews.llvm.org/D86069