[PATCH] D49508: [Sema] Mark implicitly-inserted ICE's as being part of explicit cast (PR38166)

[Richard Smith - zygoloid via Phabricator via llvm-commits]

rsmith added inline comments.


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Comment at: include/clang/AST/Stmt.h:206
+    bool PartOfExplicitCast : 1;
+    unsigned BasePathSize : 32 - 6 - 1 - NumExprBits;
   };
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lebedev.ri wrote:
> rjmccall wrote:
> > lebedev.ri wrote:
> > > rjmccall wrote:
> > > > This needs to be serialized.
> > > Uhm, could you please explain what do you mean by 'serialized'?
> > It needs to be preserved when writing an ICE into a PCH / module file.  See the ASTWriter / ASTReader.
> Aha. I did add handling there but it raises questions:
>   #  This will silently break with different AST serialization versions.
>      I'm not sure how to handle it, since `VERSION_MINOR` isn't even read back.
>   #  //Does// this need a test? How to write one?
>      Like `./test/PCH/include-timestamp.cpp`, using `llvm-bcanalyzer`?
Don't worry about breaking the serialization format. We do not maintain AST file format compatibility in general (neither between major releases nor between any two arbitrary SVN revisions). [We should probably maintain file format compatibility between patch releases, but I don't think that works right now because we check the full version number including the patch level when reading a file.]

Please do add a test: what you need to do is create a PCH containing an implicit cast expression and then import that AST file and do anything to check that the value is preserved (such as inspecting the output of `-ast-dump`). Maybe you could add this to the existing `test/PCH/cxx_exprs.cpp` test, which already does most of what you want, but doesn't have any `FileCheck` tests on the `-ast-dump` output yet.


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Comment at: lib/AST/ASTDumper.cpp:2122
+  if (Node->getIsPartOfExplicitCast())
+    OS << " PartOfExplicitCast";
 }
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Our predominant convention is to use lower_snake_case for such things in `-ast-dump` (though we're not exactly consistent on this...)


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Comment at: lib/Sema/SemaCast.cpp:94-101
+    void updatePartOfExplicitCastFlags(CastExpr *CE) {
+      // Walk down from the CE to the OrigSrcExpr, and mark all immediate
+      // ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE
+      // (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched.
+      while (OrigSrcExpr.get() != CE->getSubExpr() &&
+             (CE = dyn_cast<ImplicitCastExpr>(CE->getSubExpr())))
+        CE->setIsPartOfExplicitCast(true);
----------------
You don't need to track the `OrigSrcExpr` here. You can just recurse down through all the `ImplicitCastExpr`s (they're always all notionally part of the explicit cast).


Repository:
  rC Clang

https://reviews.llvm.org/D49508