bruno created this revision.
bruno added reviewers: manmanren, akyrtzi, rsmith.
bruno added a subscriber: cfe-commits.
`RawComments` are sorted by comparing underlying `SourceLocation`'s. This is
done by comparing `FileID` and `Offset`; when the `FileID` is the same it means
the locations are within the same TU and the `Offset` is used, etc.
FileID, from the source code: "A mostly-opaque identifier, where 0 is
"invalid", >0 is this module, and <-1 is something loaded from another
module.". That said, when de-serializing SourceLocations, FileID's from
RawComments loaded from other modules get negative IDs where previously they
were positive. This makes imported RawComments unsorted, leading to a wrong
merge with other comments from the current TU. Fix that by sorting RawComments
properly after de-serialization and before merge.
This fixes an assertion in `ASTContext::getRawCommentForDeclNoCache`, which
fires only in a debug build of clang. There's seems to be no reliable way to
test this.
Additionally, I tried to use `llvm::array_pod_sort`, but that didn't seem to
cope well with `BeforeThanCompare(SourceMgr)` or lambdas, and a
`SourceMgr` is needed to perform the sort.
https://reviews.llvm.org/D27546
Files:
lib/Serialization/ASTReader.cpp
Index: lib/Serialization/ASTReader.cpp
===
--- lib/Serialization/ASTReader.cpp
+++ lib/Serialization/ASTReader.cpp
@@ -8481,6 +8481,10 @@
}
}
NextCursor:
+// De-serialized SourceLocations get negative FileIDs for other modules,
+// potentially invalidating the original order. Sort it again.
+std::sort(Comments.begin(), Comments.end(),
+ BeforeThanCompare(SourceMgr));
Context.Comments.addDeserializedComments(Comments);
}
}
Index: lib/Serialization/ASTReader.cpp
===
--- lib/Serialization/ASTReader.cpp
+++ lib/Serialization/ASTReader.cpp
@@ -8481,6 +8481,10 @@
}
}
NextCursor:
+// De-serialized SourceLocations get negative FileIDs for other modules,
+// potentially invalidating the original order. Sort it again.
+std::sort(Comments.begin(), Comments.end(),
+ BeforeThanCompare(SourceMgr));
Context.Comments.addDeserializedComments(Comments);
}
}
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