[PATCH] D73723: [clangd][Hover] Handle uninstantiated default args

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet created this revision.
kadircet added reviewers: sammccall, ilya-biryukov.
Herald added subscribers: cfe-commits, usaxena95, arphaman, jkorous, MaskRay.
Herald added a project: clang.

Default args might exist but be unparsed or uninstantiated.
getDefaultArg asserts on those. This patch makes sure we don't crash in such
scenarios.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D73723

Files:
  clang-tools-extra/clangd/Hover.cpp
  clang-tools-extra/clangd/unittests/HoverTests.cpp


Index: clang-tools-extra/clangd/unittests/HoverTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/HoverTests.cpp
+++ clang-tools-extra/clangd/unittests/HoverTests.cpp
@@ -1609,6 +1609,22 @@
             HI.Type = "unsigned long";
             HI.Value = "1";
           }},
+      {
+          R"cpp(
+          template <typename T = int>
+          void foo(const T& = T()) {
+            [[f^oo]]<>(3);
+          })cpp",
+          [](HoverInfo &HI) {
+            HI.Name = "foo";
+            HI.Kind = index::SymbolKind::Function;
+            HI.Type = "void (const int &)";
+            HI.ReturnType = "void";
+            HI.Parameters = {
+                {std::string("const int &"), llvm::None, std::string("T()")}};
+            HI.Definition = "template <> void foo<int>(const int &)";
+            HI.NamespaceScope = "";
+          }},
   };
 
   // Create a tiny index, so tests above can verify documentation is fetched.
Index: clang-tools-extra/clangd/Hover.cpp
===================================================================
--- clang-tools-extra/clangd/Hover.cpp
+++ clang-tools-extra/clangd/Hover.cpp
@@ -269,10 +269,17 @@
     }
     if (!PVD->getName().empty())
       P.Name = PVD->getNameAsString();
-    if (PVD->hasDefaultArg()) {
+    // Default argument can be unparsed or uninstatiated. For the former we
+    // can't do much as token information is only stored in Sema and not
+    // attached to the AST node. For the latter though, it is safe to proceed as
+    // we only print the expression.
+    if (PVD->hasDefaultArg() && !PVD->hasUnparsedDefaultArg()) {
       P.Default.emplace();
       llvm::raw_string_ostream Out(*P.Default);
-      PVD->getDefaultArg()->printPretty(Out, nullptr, Policy);
+      const Expr *Init = PVD->hasUninstantiatedDefaultArg()
+                             ? PVD->getUninstantiatedDefaultArg()
+                             : PVD->getDefaultArg();
+      Init->printPretty(Out, nullptr, Policy);
     }
   }
 


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