[clangd] Suggest adding missing includes for typos (like include-fixer).

Summary:
This adds include-fixer feature into clangd based on D56903. Clangd now captures
diagnostics caused by typos and attach include insertion fixes to potentially
fix the typo.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: cfe-commits, kadircet, arphaman, mgrang, jkorous, MaskRay, javed.absar, ilya-biryukov, mgorny

Tags: #clang

Differential Revision: https://reviews.llvm.org/D57021

llvm-svn: 353380

1 files changed, 35 insertions, 2 deletions

diff --git a/clang-tools-extra/clangd/IncludeFixer.h b/clang-tools-extra/clangd/IncludeFixer.h
index 740710cf4ea..da292b56b00 100644
--- a/clang-tools-extra/clangd/IncludeFixer.h
+++ b/clang-tools-extra/clangd/IncludeFixer.h
@@ -14,6 +14,13 @@
 #include "index/Index.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Sema/ExternalSemaSource.h"
+#include "clang/Sema/Sema.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/IntrusiveRefCntPtr.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include <memory>
 
@@ -34,18 +41,44 @@ public:
   std::vector<Fix> fix(DiagnosticsEngine::Level DiagLevel,
                        const clang::Diagnostic &Info) const;
 
+  /// Returns an ExternalSemaSource that records failed name lookups in Sema.
+  /// This allows IncludeFixer to suggest inserting headers that define those
+  /// names.
+  llvm::IntrusiveRefCntPtr<ExternalSemaSource> unresolvedNameRecorder();
+
 private:
   /// Attempts to recover diagnostic caused by an incomplete type \p T.
   std::vector<Fix> fixIncompleteType(const Type &T) const;
 
-  /// Generates header insertion fixes for \p Sym.
-  std::vector<Fix> fixesForSymbol(const Symbol &Sym) const;
+  /// Generates header insertion fixes for all symbols. Fixes are deduplicated.
+  std::vector<Fix> fixesForSymbols(llvm::ArrayRef<Symbol> Syms) const;
+
+  struct UnresolvedName {
+    std::string Name;   // E.g. "X" in foo::X.
+    SourceLocation Loc; // Start location of the unresolved name.
+    // Lazily get the possible scopes of the unresolved name. `Sema` must be
+    // alive when this is called.
+    std::function<std::vector<std::string>()> GetScopes;
+  };
+
+  /// Records the last unresolved name seen by Sema.
+  class UnresolvedNameRecorder;
+
+  /// Attempts to fix the unresolved name associated with the current
+  /// diagnostic. We assume a diagnostic is caused by a unresolved name when
+  /// they have the same source location and the unresolved name is the last
+  /// one we've seen during the Sema run.
+  std::vector<Fix> fixUnresolvedName() const;
 
   std::string File;
   std::shared_ptr<IncludeInserter> Inserter;
   const SymbolIndex &Index;
   const unsigned IndexRequestLimit; // Make at most 5 index requests.
   mutable unsigned IndexRequestCount = 0;
+
+  // These collect the last unresolved name so that we can associate it with the
+  // diagnostic.
+  llvm::Optional<UnresolvedName> LastUnresolvedName;
 };
 
 } // namespace clangd