[clangd] More complete fix for hover crashes on invalid record.

[hokein]

Summary

We should not call getFieldOffset on invalid record decls.

[kadircet]

thanks for doing this !

clang-tools-extra/clangd/Hover.cpp

667

i think we should bail out for invalid decls in here too. it won't crash but will provide spurious results. so i think an early exit for ND.isInvalidDecl() at the beginning of the function would be nice.

679–680

could you move this out of the if statement.

[hokein]

address comment.

clang-tools-extra/clangd/Hover.cpp

679–680

I'm not sure whether Size and Offset should be be independent, IIUC your fix seems to change it as a side effect, this just preserves the old behavior.

[kadircet]

clang-tools-extra/clangd/Hover.cpp

679–680

it wasn't a side effect, it was intentional and stamped (and explicitly spelled out in the description)

[hokein]

clang-tools-extra/clangd/Hover.cpp

679–680

ah, OK, changed it back.

[hokein]

address comment.

clang-tools-extra/clangd/Hover.cpp

 }
 
 bool isHardLineBreakAfter(llvm::StringRef Line, llvm::StringRef Rest) {
   // Should we also consider whether Line is short?
   return punctuationIndicatesLineBreak(Line) || isHardLineBreakIndicator(Rest);
 }
 
 void addLayoutInfo(const NamedDecl &ND, HoverInfo &HI) {
-  const auto &Ctx = ND.getASTContext();
+  if (ND.isInvalidDecl())
+    return;
 
+  const auto &Ctx = ND.getASTContext();
   if (auto *RD = llvm::dyn_cast<RecordDecl>(&ND)) {
     if (auto Size = Ctx.getTypeSizeInCharsIfKnown(RD->getTypeForDecl()))
       HI.Size = Size->getQuantity();
     return;
   }
 
   if (const auto *FD = llvm::dyn_cast<FieldDecl>(&ND)) {
     const auto *Record = FD->getParent();
     if (Record)
       Record = Record->getDefinition();
-    if (Record && !Record->isDependentType()) {
+    if (Record && !Record->isInvalidDecl() && !Record->isDependentType()) {
+      HI.Offset = Ctx.getFieldOffset(FD) / 8;
       if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType()))
         HI.Size = Size->getQuantity();
-      if (!FD->isInvalidDecl())
-        HI.Offset = Ctx.getFieldOffset(FD) / 8;
     }
     return;
   }
 }
 
 // If N is passed as argument to a function, fill HI.CalleeArgInfo with
 // information about that argument.
 void maybeAddCalleeArgInfo(const SelectionTree::Node *N, HoverInfo &HI,
                            const PrintingPolicy &Policy) {

clang-tools-extra/clangd/unittests/HoverTests.cpp

class Foo {})cpp";
           Bar [[x^x]];
         };)cpp",
        [](HoverInfo &HI) {
          HI.Name = "xx";
          HI.Kind = index::SymbolKind::Field;
          HI.NamespaceScope = "";
          HI.Definition = "int xx";
          HI.LocalScope = "Foo::";
-         HI.Size = 4;
          HI.Type = "int";
          HI.AccessSpecifier = "public";
        }},
-  };
+      {R"cpp(
+        // error-ok
+        struct Foo {
+          Bar xx;
+          int [[y^y]];
+        };)cpp",
+       [](HoverInfo &HI) {
+         HI.Name = "yy";
+         HI.Kind = index::SymbolKind::Field;
+         HI.NamespaceScope = "";
+         HI.Definition = "int yy";
+         HI.LocalScope = "Foo::";
+         HI.Type = "int";
+         HI.AccessSpecifier = "public";
+       }}};
   for (const auto &Case : Cases) {
     SCOPED_TRACE(Case.Code);
 
     Annotations T(Case.Code);
     TestTU TU = TestTU::withCode(T.code());
     TU.ExtraArgs.push_back("-std=c++17");
     // Types might be different depending on the target triplet, we chose a
     // fixed one to make sure tests passes on different platform.