[PATCH] D143096: [clangd] Provide patched diagnostics with preamble patch

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet added inline comments.


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Comment at: clang-tools-extra/clangd/Preamble.cpp:625
+// same spelling.
+static std::vector<Diag> patchDiags(llvm::ArrayRef<Diag> BaselineDiags,
+                                    const ScannedPreamble &BaselineScan,
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sammccall wrote:
> I think this function is too long with too many local lambdas, consider converting it to a class instead (call me old-fashioned!)
well it's gonna be an equally long class, but sure :D


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Comment at: clang-tools-extra/clangd/Preamble.cpp:645
+    auto ModifiedStartIt =
+        ModifiedContentsToLine.find(BaselineScan.Lines[BaselineStart]);
+    if (ModifiedStartIt == ModifiedContentsToLine.end())
----------------
sammccall wrote:
> we're assuming that the ranges are within the preamble and everyone agrees about the bounds. If not, BaselineStart may not be a valid index into BaselineScan.Lines
> 
> This assumption seems broadly reasonable, but is *very much* not locally enforced. I'd suggest a defensive check or at least an assert.
oops, thanks! both here and also the multi-ine check below.


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Comment at: clang-tools-extra/clangd/Preamble.cpp:648
+      return std::nullopt;
+    int Closest = ModifiedStartIt->second.front();
+    for (auto AlternateLine : ModifiedStartIt->second) {
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sammccall wrote:
> this doesn't look right: you're first deciding which possible starting point is closest, and then deciding whether it matches. So a range that matches can be masked by a range where only the first line matches, if the latter is closer.
i thought because this would be rare it's fine to not do that, but the same applies in the other direction as well :D
moved the content based matching inside the loop to consider a line as alternative only after it matches the contents.


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Comment at: clang-tools-extra/clangd/Preamble.cpp:706
+    Diag NewDiag;
+    // Copy all fields but Notes, Fixes, Name and Tags.
+    static_cast<DiagBase &>(NewDiag) = static_cast<DiagBase>(D);
----------------
sammccall wrote:
> reasoning about the fields you're *not* rewriting feels fragile. (Here and in TranslateFix).
> 
> Consider copying the whole object and mutating in place (`bool TranslateDiag(Diag&)` together with `erase_if`)
well i am a little worried about copying around notes/fixes just to drop them again (which can have quite some strings). but probably rare enough in practice to not matter.


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Comment at: clang-tools-extra/clangd/unittests/PreambleTests.cpp:820
+  {
+    // Note is also dropped if diag is gone.
+    Annotations Code(R"(
----------------
sammccall wrote:
> i'm confused about what this comment is getting at - a note without a diag is not even representable
well, it is to make sure we're not promoting an orphaned note to a main diag. updated the comment but happy to drop if you think it's confusing rather than being helpful.


Repository:
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  https://reviews.llvm.org/D143096/new/

https://reviews.llvm.org/D143096