[PATCH] D75483: [Sema] Fix a crash when attaching comments to an implicit decl

[Erik Pilkington via Phabricator via cfe-commits]

erik.pilkington created this revision.
erik.pilkington added a reviewer: jkorous.
Herald added subscribers: ributzka, dexonsmith.

When an implicitly generated decl was the first entry in the group, we attempted to lookup comments with an empty FileID, leading to crashes. Avoid this by trying to use the other declarations in a group, then bailing out if none are valid.

rdar://59919733


https://reviews.llvm.org/D75483

Files:
  clang/lib/AST/ASTContext.cpp
  clang/test/Sema/warn-documentation.m


Index: clang/test/Sema/warn-documentation.m
===================================================================
--- clang/test/Sema/warn-documentation.m
+++ clang/test/Sema/warn-documentation.m
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -fblocks -Wno-objc-root-class -Wdocumentation -Wdocumentation-pedantic -verify %s
+// RUN: %clang_cc1 -xobjective-c++ -fsyntax-only -fblocks -Wno-objc-root-class -Wdocumentation -Wdocumentation-pedantic -verify %s
 
 @class NSString;
 
@@ -318,3 +319,10 @@
 // expected-warning at -1 {{'\return' command used in a comment that is not attached to a function or method declaration}}
 VoidBlockTypeCall ^e; ///< \return none
 // expected-warning at -1 {{'\return' command used in a comment that is not attached to a function or method declaration}}
+
+#ifdef __cplusplus
+ at interface HasAnonNamespace @end
+ at implementation HasAnonNamespace
+namespace {}
+ at end
+#endif
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -474,10 +474,20 @@
   if (Comments.empty() || Decls.empty())
     return;
 
-  // See if there are any new comments that are not attached to a decl.
-  // The location doesn't have to be precise - we care only about the file.
-  const FileID File =
-      SourceMgr.getDecomposedLoc((*Decls.begin())->getLocation()).first;
+  FileID File;
+  for (Decl *D : Decls) {
+    SourceLocation Loc = D->getLocation();
+    if (Loc.isValid()) {
+      // See if there are any new comments that are not attached to a decl.
+      // The location doesn't have to be precise - we care only about the file.
+      File = SourceMgr.getDecomposedLoc(Loc).first;
+      break;
+    }
+  }
+
+  if (File.isInvalid())
+    return;
+
   auto CommentsInThisFile = Comments.getCommentsInFile(File);
   if (!CommentsInThisFile || CommentsInThisFile->empty() ||
       CommentsInThisFile->rbegin()->second->isAttached())


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