[SyntaxTree] Artificial use of the Mutations API.

[eduucaldas]

Summary

Not intended for submission.

[eduucaldas]

Rebase

[eduucaldas]

This patch implements the use case we discussed. It is merely for illustration.

[eduucaldas]

Rebase

clang/include/clang/Tooling/Syntax/Mutations.h

 /// Removes a statement or replaces it with an empty statement where one is
 /// required syntactically. E.g., in the following example:
 ///     if (cond) { foo(); } else bar();
 /// One can remove `foo();` completely and to remove `bar();` we would need to
 /// replace it with an empty statement.
 /// EXPECTS: S->canModify() == true
 void removeStatement(syntax::Arena &A, syntax::Statement *S);
 
+void parenthesizeRHS(syntax::Arena &A, syntax::BinaryOperatorExpression *BOE);
 } // namespace syntax
 } // namespace clang
 
 #endif

clang/lib/Tooling/Syntax/Mutations.cpp

 //===- Mutations.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 "clang/Tooling/Syntax/Mutations.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/Token.h"
 #include "clang/Tooling/Core/Replacement.h"
 #include "clang/Tooling/Syntax/BuildTree.h"
 #include "clang/Tooling/Syntax/Nodes.h"
 #include "clang/Tooling/Syntax/Tokens.h"
 #include "clang/Tooling/Syntax/Tree.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
if (isa<CompoundStatement>(S->getParent())) {
     return;
   }
   // For the rest, we have to replace with an empty statement.
   if (isa<EmptyStatement>(S))
     return; // already an empty statement, nothing to do.
 
   MutationsImpl::replace(S, createEmptyStatement(A));
 }
+
+void syntax::parenthesizeRHS(syntax::Arena &A,
+                             syntax::BinaryOperatorExpression *BOE) {
+  assert(BOE);
+  assert(BOE->canModify());
+
+  auto *RHS = BOE->getRhs();
+  auto *BeforeRHS = findPrevious(RHS);
+  MutationsImpl::remove(RHS);
+
+  auto *NewRHS =
+      createTree(A,
+                 {{createLeaf(A, tok::l_paren), NodeRole::OpenParen},
+                  {RHS, NodeRole::SubExpression},
+                  {createLeaf(A, tok::r_paren), NodeRole::CloseParen}},
+                 NodeKind::ParenExpression);
+
+  MutationsImpl::addAfter(BeforeRHS, NewRHS, NodeRole::RightHandSide);
+}

clang/unittests/Tooling/Syntax/MutationsTest.cpp

Transformation RemoveStatement = [this](const llvm::Annotations &Input,
                                           TranslationUnit *Root) {
     auto *S = cast<syntax::Statement>(nodeByRange(Input.range(), Root));
     ASSERT_TRUE(S->canModify()) << "cannot remove a statement";
     syntax::removeStatement(*Arena, S);
     EXPECT_TRUE(S->isDetached());
     EXPECT_FALSE(S->isOriginal())
         << "node removed from tree cannot be marked as original";
   };
+
+  Transformation ParenthesizeRHS = [this](const llvm::Annotations &Input,
+                                          TranslationUnit *Root) {
+    auto *BOE = cast<syntax::BinaryOperatorExpression>(
+        nodeByRange(Input.range(), Root));
+    ASSERT_TRUE(BOE->canModify()) << "cannot remove a statement";
+    syntax::parenthesizeRHS(*Arena, BOE);
+    EXPECT_FALSE(BOE->isOriginal())
+        << "modified node cannot be marked as original";
+  };
 };
 
 INSTANTIATE_TEST_CASE_P(SyntaxTreeTests, MutationTest,
                         ::testing::ValuesIn(allTestClangConfigs()), );
 
 TEST_P(MutationTest, RemoveStatement_InCompound) {
   CheckTransformation(RemoveStatement, "void test() { [[100+100;]] test(); }",
                       "void test() {  test(); }");
 }
 
 TEST_P(MutationTest, RemoveStatement_InCompound_Empty) {
   CheckTransformation(RemoveStatement, "void test() { [[;]] }",
                       "void test() {  }");
 }
 
 TEST_P(MutationTest, RemoveStatement_LeaveEmpty) {
   CheckTransformation(RemoveStatement, "void test() { if (1) [[{}]] else {} }",
                       "void test() { if (1) ; else {} }");
 }
+
+TEST_P(MutationTest, Parenthesize_RHS) {
+  CheckTransformation(ParenthesizeRHS, R"cpp(void test() { [[1 + 2]]; })cpp",
+                      "void test() { 1 + (2); }");
+}
+
+TEST_P(MutationTest, Parenthesize_RHS_MACRO) {
+  CheckTransformation(ParenthesizeRHS, R"cpp(
+#define THENUMBER 42
+void test() {
+  [[1 + (THENUMBER)]];
+})cpp",
+                      R"cpp(
+#define THENUMBER 42
+void test() {
+  1 + ((THENUMBER));
+})cpp");
+}
 } // namespace