[clangd] Fix hover crash on invalid decls

Summary: This also changes the way we display Size and Offset to be independent.

Reviewers: sammccall

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83143
diff --git a/clang-tools-extra/clangd/Hover.cpp b/clang-tools-extra/clangd/Hover.cpp
index 616d4c9..f495052 100644
--- a/clang-tools-extra/clangd/Hover.cpp
+++ b/clang-tools-extra/clangd/Hover.cpp
@@ -672,11 +672,10 @@
     if (Record)
       Record = Record->getDefinition();
     if (Record && !Record->isDependentType()) {
-      uint64_t OffsetBits = Ctx.getFieldOffset(FD);
-      if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType())) {
+      if (auto Size = Ctx.getTypeSizeInCharsIfKnown(FD->getType()))
         HI.Size = Size->getQuantity();
-        HI.Offset = OffsetBits / 8;
-      }
+      if (!FD->isInvalidDecl())
+        HI.Offset = Ctx.getFieldOffset(FD) / 8;
     }
     return;
   }
diff --git a/clang-tools-extra/clangd/unittests/HoverTests.cpp b/clang-tools-extra/clangd/unittests/HoverTests.cpp
index 4059f83..3be796a 100644
--- a/clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ b/clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -772,6 +772,22 @@
          HI.CallPassType->PassBy = PassMode::Value;
          HI.CallPassType->Converted = false;
        }},
+      {// Dont crash on invalid decl
+       R"cpp(
+        // error-ok
+        struct Foo {
+          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";
+       }},
   };
   for (const auto &Case : Cases) {
     SCOPED_TRACE(Case.Code);