Importing rustc-1.38.0
diff --git a/src/llvm-project/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp b/src/llvm-project/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp
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+++ b/src/llvm-project/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp
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+//===--- ExtractVariable.cpp ------------------------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#include "ClangdUnit.h"
+#include "Logger.h"
+#include "Protocol.h"
+#include "Selection.h"
+#include "SourceCode.h"
+#include "refactor/Tweak.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/OperationKinds.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Tooling/Core/Replacement.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Error.h"
+
+namespace clang {
+namespace clangd {
+namespace {
+// information regarding the Expr that is being extracted
+class ExtractionContext {
+public:
+ ExtractionContext(const SelectionTree::Node *Node, const SourceManager &SM,
+ const ASTContext &Ctx);
+ const clang::Expr *getExpr() const { return Expr; }
+ const SelectionTree::Node *getExprNode() const { return ExprNode; }
+ bool isExtractable() const { return Extractable; }
+ // Generate Replacement for replacing selected expression with given VarName
+ tooling::Replacement replaceWithVar(llvm::StringRef VarName) const;
+ // Generate Replacement for declaring the selected Expr as a new variable
+ tooling::Replacement insertDeclaration(llvm::StringRef VarName) const;
+
+private:
+ bool Extractable = false;
+ const clang::Expr *Expr;
+ const SelectionTree::Node *ExprNode;
+ // Stmt before which we will extract
+ const clang::Stmt *InsertionPoint = nullptr;
+ const SourceManager &SM;
+ const ASTContext &Ctx;
+ // Decls referenced in the Expr
+ std::vector<clang::Decl *> ReferencedDecls;
+ // returns true if the Expr doesn't reference any variable declared in scope
+ bool exprIsValidOutside(const clang::Stmt *Scope) const;
+ // computes the Stmt before which we will extract out Expr
+ const clang::Stmt *computeInsertionPoint() const;
+};
+
+// Returns all the Decls referenced inside the given Expr
+static std::vector<clang::Decl *>
+computeReferencedDecls(const clang::Expr *Expr) {
+ // RAV subclass to find all DeclRefs in a given Stmt
+ class FindDeclRefsVisitor
+ : public clang::RecursiveASTVisitor<FindDeclRefsVisitor> {
+ public:
+ std::vector<Decl *> ReferencedDecls;
+ bool VisitDeclRefExpr(DeclRefExpr *DeclRef) { // NOLINT
+ ReferencedDecls.push_back(DeclRef->getDecl());
+ return true;
+ }
+ };
+ FindDeclRefsVisitor Visitor;
+ Visitor.TraverseStmt(const_cast<Stmt *>(dyn_cast<Stmt>(Expr)));
+ return Visitor.ReferencedDecls;
+}
+
+// An expr is not extractable if it's null or an expression of type void
+// FIXME: Ignore assignment (a = 1) Expr since it is extracted as dummy = a =
+static bool isExtractableExpr(const clang::Expr *Expr) {
+ if (Expr) {
+ const Type *ExprType = Expr->getType().getTypePtrOrNull();
+ // FIXME: check if we need to cover any other types
+ if (ExprType)
+ return !ExprType->isVoidType();
+ }
+ return false;
+}
+
+ExtractionContext::ExtractionContext(const SelectionTree::Node *Node,
+ const SourceManager &SM,
+ const ASTContext &Ctx)
+ : ExprNode(Node), SM(SM), Ctx(Ctx) {
+ Expr = Node->ASTNode.get<clang::Expr>();
+ if (isExtractableExpr(Expr)) {
+ ReferencedDecls = computeReferencedDecls(Expr);
+ InsertionPoint = computeInsertionPoint();
+ if (InsertionPoint)
+ Extractable = true;
+ }
+}
+
+// checks whether extracting before InsertionPoint will take a
+// variable reference out of scope
+bool ExtractionContext::exprIsValidOutside(const clang::Stmt *Scope) const {
+ SourceLocation ScopeBegin = Scope->getBeginLoc();
+ SourceLocation ScopeEnd = Scope->getEndLoc();
+ for (const Decl *ReferencedDecl : ReferencedDecls) {
+ if (SM.isPointWithin(ReferencedDecl->getBeginLoc(), ScopeBegin, ScopeEnd) &&
+ SM.isPointWithin(ReferencedDecl->getEndLoc(), ScopeBegin, ScopeEnd))
+ return false;
+ }
+ return true;
+}
+
+// Return the Stmt before which we need to insert the extraction.
+// To find the Stmt, we go up the AST Tree and if the Parent of the current
+// Stmt is a CompoundStmt, we can extract inside this CompoundStmt just before
+// the current Stmt. We ALWAYS insert before a Stmt whose parent is a
+// CompoundStmt
+//
+
+// FIXME: Extraction from switch and case statements
+// FIXME: Doens't work for FoldExpr
+const clang::Stmt *ExtractionContext::computeInsertionPoint() const {
+ // returns true if we can extract before InsertionPoint
+ auto CanExtractOutside =
+ [](const SelectionTree::Node *InsertionPoint) -> bool {
+ if (const clang::Stmt *Stmt = InsertionPoint->ASTNode.get<clang::Stmt>()) {
+ // Allow all expressions except LambdaExpr since we don't want to extract
+ // from the captures/default arguments of a lambda
+ if (isa<clang::Expr>(Stmt))
+ return !isa<LambdaExpr>(Stmt);
+ // We don't yet allow extraction from switch/case stmt as we would need to
+ // jump over the switch stmt even if there is a CompoundStmt inside the
+ // switch. And there are other Stmts which we don't care about (e.g.
+ // continue and break) as there can never be anything to extract from
+ // them.
+ return isa<AttributedStmt>(Stmt) || isa<CompoundStmt>(Stmt) ||
+ isa<CXXForRangeStmt>(Stmt) || isa<DeclStmt>(Stmt) ||
+ isa<DoStmt>(Stmt) || isa<ForStmt>(Stmt) || isa<IfStmt>(Stmt) ||
+ isa<LabelStmt>(Stmt) || isa<ReturnStmt>(Stmt) ||
+ isa<WhileStmt>(Stmt);
+ }
+ if (InsertionPoint->ASTNode.get<VarDecl>())
+ return true;
+ return false;
+ };
+ for (const SelectionTree::Node *CurNode = getExprNode();
+ CurNode->Parent && CanExtractOutside(CurNode);
+ CurNode = CurNode->Parent) {
+ const clang::Stmt *CurInsertionPoint = CurNode->ASTNode.get<Stmt>();
+ // give up if extraction will take a variable out of scope
+ if (CurInsertionPoint && !exprIsValidOutside(CurInsertionPoint))
+ break;
+ if (const clang::Stmt *CurParent = CurNode->Parent->ASTNode.get<Stmt>()) {
+ if (isa<CompoundStmt>(CurParent)) {
+ // Ensure we don't write inside a macro.
+ if (CurParent->getBeginLoc().isMacroID())
+ continue;
+ return CurInsertionPoint;
+ }
+ }
+ }
+ return nullptr;
+}
+// returns the replacement for substituting the extraction with VarName
+tooling::Replacement
+ExtractionContext::replaceWithVar(llvm::StringRef VarName) const {
+ const llvm::Optional<SourceRange> ExtractionRng =
+ toHalfOpenFileRange(SM, Ctx.getLangOpts(), getExpr()->getSourceRange());
+ unsigned ExtractionLength = SM.getFileOffset(ExtractionRng->getEnd()) -
+ SM.getFileOffset(ExtractionRng->getBegin());
+ return tooling::Replacement(SM, ExtractionRng->getBegin(), ExtractionLength,
+ VarName);
+}
+// returns the Replacement for declaring a new variable storing the extraction
+tooling::Replacement
+ExtractionContext::insertDeclaration(llvm::StringRef VarName) const {
+ const llvm::Optional<SourceRange> ExtractionRng =
+ toHalfOpenFileRange(SM, Ctx.getLangOpts(), getExpr()->getSourceRange());
+ assert(ExtractionRng && "ExtractionRng should not be null");
+ llvm::StringRef ExtractionCode = toSourceCode(SM, *ExtractionRng);
+ const SourceLocation InsertionLoc =
+ toHalfOpenFileRange(SM, Ctx.getLangOpts(),
+ InsertionPoint->getSourceRange())
+ ->getBegin();
+ // FIXME: Replace auto with explicit type and add &/&& as necessary
+ std::string ExtractedVarDecl = std::string("auto ") + VarName.str() + " = " +
+ ExtractionCode.str() + "; ";
+ return tooling::Replacement(SM, InsertionLoc, 0, ExtractedVarDecl);
+}
+
+/// Extracts an expression to the variable dummy
+/// Before:
+/// int x = 5 + 4 * 3;
+/// ^^^^^
+/// After:
+/// auto dummy = 5 + 4;
+/// int x = dummy * 3;
+class ExtractVariable : public Tweak {
+public:
+ const char *id() const override final;
+ bool prepare(const Selection &Inputs) override;
+ Expected<Effect> apply(const Selection &Inputs) override;
+ std::string title() const override {
+ return "Extract subexpression to variable";
+ }
+ Intent intent() const override { return Refactor; }
+
+private:
+ // the expression to extract
+ std::unique_ptr<ExtractionContext> Target;
+};
+REGISTER_TWEAK(ExtractVariable)
+bool ExtractVariable::prepare(const Selection &Inputs) {
+ const ASTContext &Ctx = Inputs.AST.getASTContext();
+ const SourceManager &SM = Inputs.AST.getSourceManager();
+ const SelectionTree::Node *N = Inputs.ASTSelection.commonAncestor();
+ // we don't trigger on empty selections for now
+ if (!N || Inputs.SelectionBegin == Inputs.SelectionEnd)
+ return false;
+ Target = llvm::make_unique<ExtractionContext>(N, SM, Ctx);
+ return Target->isExtractable();
+}
+
+Expected<Tweak::Effect> ExtractVariable::apply(const Selection &Inputs) {
+ tooling::Replacements Result;
+ // FIXME: get variable name from user or suggest based on type
+ std::string VarName = "dummy";
+ // insert new variable declaration
+ if (auto Err = Result.add(Target->insertDeclaration(VarName)))
+ return std::move(Err);
+ // replace expression with variable name
+ if (auto Err = Result.add(Target->replaceWithVar(VarName)))
+ return std::move(Err);
+ return Effect::applyEdit(Result);
+}
+
+} // namespace
+} // namespace clangd
+} // namespace clang
