[ClangTidy] Add UsingInserter and NamespaceAliaser

Summary: This adds helper classes to add using declaractions and namespace aliases to function bodies. These help making function calls to deeply nested functions concise (e.g. when calling helpers in a refactoring)

Patch by Julian Bangert!

Reviewers: alexfh, hokein

Subscribers: cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D24997

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@283981 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 342 insertions, 0 deletions

diff --git a/clang-tidy/utils/ASTUtils.cpp b/clang-tidy/utils/ASTUtils.cpp
new file mode 100644
index 00000000..b95cd54d
--- /dev/null
+++ b/clang-tidy/utils/ASTUtils.cpp
@@ -0,0 +1,28 @@
+//===---------- ASTUtils.cpp - clang-tidy ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ASTUtils.h"
+
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+using namespace ast_matchers;
+
+const FunctionDecl *getSurroundingFunction(ASTContext &Context,
+                                           const Stmt &Statement) {
+  return selectFirst<const FunctionDecl>(
+      "function", match(stmt(hasAncestor(functionDecl().bind("function"))),
+                        Statement, Context));
+}
+} // namespace utils
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tidy/utils/ASTUtils.h b/clang-tidy/utils/ASTUtils.h
new file mode 100644
index 00000000..85ba7376
--- /dev/null
+++ b/clang-tidy/utils/ASTUtils.h
@@ -0,0 +1,25 @@
+//===---------- ASTUtils.h - clang-tidy ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ASTUTILS_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ASTUTILS_H
+
+#include "clang/AST/AST.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+// Returns the (closest) Function declaration surrounding |Statement| or NULL.
+const FunctionDecl *getSurroundingFunction(ASTContext &Context,
+                                           const Stmt &Statement);
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ASTUTILS_H
diff --git a/clang-tidy/utils/NamespaceAliaser.cpp b/clang-tidy/utils/NamespaceAliaser.cpp
new file mode 100644
index 00000000..04fdb8cd
--- /dev/null
+++ b/clang-tidy/utils/NamespaceAliaser.cpp
@@ -0,0 +1,99 @@
+//===---------- NamespaceAliaser.cpp - clang-tidy -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NamespaceAliaser.h"
+
+#include "ASTUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Lex/Lexer.h"
+namespace clang {
+namespace tidy {
+namespace utils {
+
+using namespace ast_matchers;
+
+NamespaceAliaser::NamespaceAliaser(const SourceManager &SourceMgr)
+    : SourceMgr(SourceMgr) {}
+
+AST_MATCHER_P(NamespaceAliasDecl, hasTargetNamespace,
+              ast_matchers::internal::Matcher<NamespaceDecl>, innerMatcher) {
+  return innerMatcher.matches(*Node.getNamespace(), Finder, Builder);
+}
+
+Optional<FixItHint>
+NamespaceAliaser::createAlias(ASTContext &Context, const Stmt &Statement,
+                              StringRef Namespace,
+                              const std::vector<std::string> &Abbreviations) {
+  const FunctionDecl *Function = getSurroundingFunction(Context, Statement);
+  if (!Function || !Function->hasBody())
+    return None;
+
+
+  if (AddedAliases[Function].count(Namespace.str()) != 0)
+    return None;
+
+
+  // FIXME: Doesn't consider the order of declarations.
+  // If we accidentially pick an alias defined later in the function,
+  // the output won't compile.
+  // FIXME: Also doesn't consider file or class-scope aliases.
+
+  const auto *ExistingAlias = selectFirst<NamedDecl>(
+      "alias",
+      match(functionDecl(hasBody(compoundStmt(has(declStmt(
+                has(namespaceAliasDecl(hasTargetNamespace(hasName(Namespace)))
+                        .bind("alias"))))))),
+            *Function, Context));
+
+  if (ExistingAlias != nullptr) {
+    AddedAliases[Function][Namespace.str()] = ExistingAlias->getName().str();
+    return None;
+  }
+
+  for (const auto &Abbreviation : Abbreviations) {
+    DeclarationMatcher ConflictMatcher = namedDecl(hasName(Abbreviation));
+    const auto HasConflictingChildren =
+        !match(findAll(ConflictMatcher), *Function, Context).empty();
+    const auto HasConflictingAncestors =
+        !match(functionDecl(hasAncestor(decl(has(ConflictMatcher)))), *Function,
+               Context)
+             .empty();
+    if (HasConflictingAncestors || HasConflictingChildren)
+      continue;
+
+    std::string Declaration =
+        (llvm::Twine("\nnamespace ") + Abbreviation + " = " + Namespace + ";")
+            .str();
+    SourceLocation Loc =
+        Lexer::getLocForEndOfToken(Function->getBody()->getLocStart(), 0,
+                                   SourceMgr, Context.getLangOpts());
+    AddedAliases[Function][Namespace.str()] = Abbreviation;
+    return FixItHint::CreateInsertion(Loc, Declaration);
+  }
+
+  return None;
+}
+
+std::string NamespaceAliaser::getNamespaceName(ASTContext &Context,
+                                               const Stmt &Statement,
+                                               StringRef Namespace) const {
+  const auto *Function = getSurroundingFunction(Context, Statement);
+  auto FunctionAliases = AddedAliases.find(Function);
+  if (FunctionAliases != AddedAliases.end()) {
+    if (FunctionAliases->second.count(Namespace) != 0) {
+      return FunctionAliases->second.find(Namespace)->getValue();
+    }
+  }
+  return Namespace.str();
+}
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tidy/utils/NamespaceAliaser.h b/clang-tidy/utils/NamespaceAliaser.h
new file mode 100644
index 00000000..e56d69d3
--- /dev/null
+++ b/clang-tidy/utils/NamespaceAliaser.h
@@ -0,0 +1,52 @@
+//===---------- NamespaceAliaser.h - clang-tidy ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_NAMESPACEALIASER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_NAMESPACEALIASER_H
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
+#include <map>
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+// This class creates function-level namespace aliases.
+class NamespaceAliaser {
+public:
+  explicit NamespaceAliaser(const SourceManager &SourceMgr);
+  // Adds a namespace alias for \p Namespace valid near \p
+  // Statement. Picks the first available name from \p Abbreviations.
+  // Returns ``llvm::None`` if an alias already exists or there is an error.
+  llvm::Optional<FixItHint>
+  createAlias(ASTContext &Context, const Stmt &Statement,
+              llvm::StringRef Namespace,
+              const std::vector<std::string> &Abbreviations);
+
+  // Get an alias name for \p Namespace valid at \p Statement. Returns \p
+  // Namespace if there is no alias.
+  std::string getNamespaceName(ASTContext &Context, const Stmt &Statement,
+                               llvm::StringRef Namespace) const;
+
+private:
+  const SourceManager &SourceMgr;
+  llvm::DenseMap<const FunctionDecl *, llvm::StringMap<std::string>>
+      AddedAliases;
+};
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_NAMESPACEALIASER_H
diff --git a/clang-tidy/utils/UsingInserter.cpp b/clang-tidy/utils/UsingInserter.cpp
new file mode 100644
index 00000000..c0746afc
--- /dev/null
+++ b/clang-tidy/utils/UsingInserter.cpp
@@ -0,0 +1,88 @@
+//===---------- UsingInserter.cpp - clang-tidy ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "UsingInserter.h"
+
+#include "ASTUtils.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Lex/Lexer.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+using namespace ast_matchers;
+
+static StringRef getUnqualifiedName(StringRef QualifiedName) {
+  size_t LastSeparatorPos = QualifiedName.rfind("::");
+  if (LastSeparatorPos == StringRef::npos)
+    return QualifiedName;
+  return QualifiedName.drop_front(LastSeparatorPos + 2);
+}
+
+UsingInserter::UsingInserter(const SourceManager &SourceMgr)
+    : SourceMgr(SourceMgr) {}
+
+Optional<FixItHint> UsingInserter::createUsingDeclaration(
+    ASTContext &Context, const Stmt &Statement, StringRef QualifiedName) {
+  StringRef UnqualifiedName = getUnqualifiedName(QualifiedName);
+  const FunctionDecl *Function = getSurroundingFunction(Context, Statement);
+  if (!Function)
+    return None;
+
+  if (AddedUsing.count(std::make_pair(Function, QualifiedName.str())) != 0)
+    return None;
+
+  SourceLocation InsertLoc = Lexer::getLocForEndOfToken(
+      Function->getBody()->getLocStart(), 0, SourceMgr, Context.getLangOpts());
+
+  // Only use using declarations in the main file, not in includes.
+  if (SourceMgr.getFileID(InsertLoc) != SourceMgr.getMainFileID())
+    return None;
+
+  // FIXME: This declaration could be masked. Investigate if
+  // there is a way to avoid using Sema.
+  bool AlreadyHasUsingDecl =
+      !match(stmt(hasAncestor(decl(has(usingDecl(hasAnyUsingShadowDecl(
+                 hasTargetDecl(hasName(QualifiedName.str())))))))),
+             Statement, Context)
+           .empty();
+  if (AlreadyHasUsingDecl) {
+    AddedUsing.emplace(NameInFunction(Function, QualifiedName.str()));
+    return None;
+  }
+  // Find conflicting declarations and references.
+  auto ConflictingDecl = namedDecl(hasName(UnqualifiedName));
+  bool HasConflictingDeclaration =
+      !match(findAll(ConflictingDecl), *Function, Context).empty();
+  bool HasConflictingDeclRef =
+      !match(findAll(declRefExpr(to(ConflictingDecl))), *Function, Context)
+           .empty();
+  if (HasConflictingDeclaration || HasConflictingDeclRef)
+    return None;
+
+  std::string Declaration = (llvm::Twine("\nusing ") + QualifiedName + ";").str();
+
+  AddedUsing.emplace(std::make_pair(Function, QualifiedName.str()));
+  return FixItHint::CreateInsertion(InsertLoc, Declaration);
+}
+
+StringRef UsingInserter::getShortName(ASTContext &Context,
+                                      const Stmt &Statement,
+                                      StringRef QualifiedName) {
+  const FunctionDecl *Function = getSurroundingFunction(Context, Statement);
+  if (AddedUsing.count(NameInFunction(Function, QualifiedName.str())) != 0)
+    return getUnqualifiedName(QualifiedName);
+  return QualifiedName;
+}
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tidy/utils/UsingInserter.h b/clang-tidy/utils/UsingInserter.h
new file mode 100644
index 00000000..b1fb7db9
--- /dev/null
+++ b/clang-tidy/utils/UsingInserter.h
@@ -0,0 +1,50 @@
+//===---------- UsingInserter.h - clang-tidy ----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_USINGINSERTER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_USINGINSERTER_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceManager.h"
+#include <set>
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+// UsingInserter adds using declarations for |QualifiedName| to the surrounding
+// function.
+// This allows using a shorter name without clobbering other scopes.
+class UsingInserter {
+public:
+  UsingInserter(const SourceManager &SourceMgr);
+
+  // Creates a \p using declaration fixit. Returns ``llvm::None`` on error
+  // or if the using declaration already exists.
+  llvm::Optional<FixItHint>
+  createUsingDeclaration(ASTContext &Context, const Stmt &Statement,
+                         llvm::StringRef QualifiedName);
+
+  // Returns the unqualified version of the name if there is an
+  // appropriate using declaration and the qualified name otherwise.
+  llvm::StringRef getShortName(ASTContext &Context, const Stmt &Statement,
+                               llvm::StringRef QualifiedName);
+
+private:
+  typedef NameInFunction std::pair<const FunctionDecl *, std::string>;
+  const SourceManager &SourceMgr;
+  std::set<NameInFunction> AddedUsing;
+};
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_USINGINSERTER_H