jvikstrom updated this revision to Diff 204269.
jvikstrom marked 3 inline comments as done.
jvikstrom added a comment.

- Added match conditionally overload to control in what language standard a 
match should run in


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63149/new/

https://reviews.llvm.org/D63149

Files:
  clang/docs/LibASTMatchersReference.html
  clang/include/clang/ASTMatchers/ASTMatchers.h
  clang/lib/ASTMatchers/Dynamic/Registry.cpp
  clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
  clang/unittests/ASTMatchers/ASTMatchersTest.h

Index: clang/unittests/ASTMatchers/ASTMatchersTest.h
===================================================================
--- clang/unittests/ASTMatchers/ASTMatchersTest.h
+++ clang/unittests/ASTMatchers/ASTMatchersTest.h
@@ -57,6 +57,17 @@
   const std::unique_ptr<BoundNodesCallback> FindResultReviewer;
 };
 
+enum class LanguageMode : int {
+  CXX11 = 0,
+  CXX14 = 1,
+  CXX17 = 2,
+  CXX20 = 3,
+  CXX11OrLater,
+  CXX14OrLater,
+  CXX17OrLater,
+  CXX20OrLater
+};
+
 template <typename T>
 testing::AssertionResult matchesConditionally(
     const std::string &Code, const T &AMatcher, bool ExpectMatch,
@@ -116,14 +127,56 @@
 }
 
 template <typename T>
-testing::AssertionResult matches(const std::string &Code, const T &AMatcher) {
-  return matchesConditionally(Code, AMatcher, true, "-std=c++11");
+testing::AssertionResult
+matchesConditionally(const std::string &Code, const T &AMatcher,
+                     bool ExpectMatch, const LanguageMode &Mode) {
+  std::vector<std::string> LangModeStrings{"-std=c++11", "-std=c++14",
+                                           "-std=c++17", "-std=c++20"};
+  std::vector<LanguageMode> LangModes;
+  switch (Mode) {
+  case LanguageMode::CXX11:
+  case LanguageMode::CXX14:
+  case LanguageMode::CXX17:
+  case LanguageMode::CXX20:
+    LangModes = {Mode};
+    break;
+  case LanguageMode::CXX11OrLater:
+    LangModes = {LanguageMode::CXX11, LanguageMode::CXX14, LanguageMode::CXX17, LanguageMode::CXX20};
+    break;
+  case LanguageMode::CXX14OrLater:
+    LangModes = {LanguageMode::CXX14, LanguageMode::CXX17, LanguageMode::CXX20};
+    break;
+  case LanguageMode::CXX17OrLater:
+    LangModes = {LanguageMode::CXX17, LanguageMode::CXX20};
+    break;
+  case LanguageMode::CXX20OrLater:
+    LangModes = {LanguageMode::CXX20};
+  };
+
+  for (auto Mode : LangModes) {
+    auto LangModeArg = LangModeStrings[static_cast<int>(Mode)];
+    auto Result =
+        matchesConditionally(Code, AMatcher, ExpectMatch, LangModeArg);
+    if (!Result) {
+      return Result;
+    }
+  }
+
+  return testing::AssertionSuccess();
 }
 
 template <typename T>
-testing::AssertionResult notMatches(const std::string &Code,
-                                    const T &AMatcher) {
-  return matchesConditionally(Code, AMatcher, false, "-std=c++11");
+testing::AssertionResult
+matches(const std::string &Code, const T &AMatcher,
+        const LanguageMode &Modes = LanguageMode::CXX11) {
+  return matchesConditionally(Code, AMatcher, true, Modes);
+}
+
+template <typename T>
+testing::AssertionResult
+notMatches(const std::string &Code, const T &AMatcher,
+           const LanguageMode &Modes = LanguageMode::CXX11) {
+  return matchesConditionally(Code, AMatcher, false, Modes);
 }
 
 template <typename T>
Index: clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
===================================================================
--- clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
+++ clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp
@@ -566,6 +566,76 @@
                                        llvm::make_unique<VerifyIdIsBoundTo<CXXMemberCallExpr>>("x")));
 }
 
+TEST(Matcher, IgnoresElidableConstructors) {
+  auto matcher1 = cxxOperatorCallExpr(hasArgument(
+      1, callExpr(hasArgument(
+             0, ignoringElidableConstructorCall(callExpr())))));
+  auto matcher2 = cxxOperatorCallExpr(hasArgument(
+      1, callExpr(hasArgument(0, ignoringElidableConstructorCall(
+                                     integerLiteral())))));
+  auto matcher3 =
+      varDecl(hasInitializer(
+        anyOf(
+        ignoringElidableConstructorCall(callExpr()),
+        exprWithCleanups(has(ignoringElidableConstructorCall(callExpr())))
+        )));
+
+  auto code1 = "struct H {};"
+               "template<typename T> H B(T A);"
+               "void f() {"
+               "  H D1;"
+               "  D1 = B(B(1));"
+               "}";
+  auto code2 = "struct H {};"
+               "template<typename T> H B(T A);"
+               "void f() {"
+               "  H D1;"
+               "  D1 = B(1);"
+               "}";
+  auto code3 = "struct H {};"
+               "H G();"
+               "void f() {"
+               "  H D = G();"
+               "}";
+
+  EXPECT_TRUE(matches(code1, matcher1, LanguageMode::CXX11OrLater));
+  EXPECT_TRUE(matches(code2, matcher2, LanguageMode::CXX11OrLater));
+  EXPECT_TRUE(matches(code3, matcher3, LanguageMode::CXX11OrLater));
+}
+
+TEST(Matcher, IgnoresElidableInReturn) {
+  auto matcher = expr(ignoringElidableConstructorCall(declRefExpr()));
+  EXPECT_TRUE(matches("struct H{};"
+                      "H f() {"
+                      "  H g;"
+                      "  return g;"
+                      "}",
+                      matcher, LanguageMode::CXX11OrLater));
+  EXPECT_TRUE(notMatches("struct H{};"
+                         "H f(){"
+                         "  return H();"
+                         "}",
+                         matcher, LanguageMode::CXX11OrLater));
+}
+
+TEST(Matcher, IgnoreElidableConstructorDoesNotMatchConstructors) {
+  auto matcher = varDecl(
+      hasInitializer(ignoringElidableConstructorCall(cxxConstructExpr())));
+  EXPECT_TRUE(matches("struct H {};"
+                      "void f() {"
+                      "  H D;"
+                      "}",
+                      matcher, LanguageMode::CXX11OrLater));
+};
+
+TEST(Matcher, IgnoresElidableDoesNotPreventMatches) {
+  EXPECT_TRUE(matches("void f() {"
+                      "  int D = 10;"
+                      "}",
+                      expr(ignoringElidableConstructorCall(integerLiteral())),
+                      LanguageMode::CXX11OrLater));
+}
+
 TEST(Matcher, BindTheSameNameInAlternatives) {
   StatementMatcher matcher = anyOf(
     binaryOperator(hasOperatorName("+"),
@@ -914,10 +984,10 @@
                       varDecl(hasName("foo"), isConstexpr())));
   EXPECT_TRUE(matches("constexpr int bar();",
                       functionDecl(hasName("bar"), isConstexpr())));
-  EXPECT_TRUE(matchesConditionally("void baz() { if constexpr(1 > 0) {} }",
-                                   ifStmt(isConstexpr()), true, "-std=c++17"));
-  EXPECT_TRUE(matchesConditionally("void baz() { if (1 > 0) {} }",
-                                   ifStmt(isConstexpr()), false, "-std=c++17"));
+  EXPECT_TRUE(matches("void baz() { if constexpr(1 > 0) {} }",
+                      ifStmt(isConstexpr()), LanguageMode::CXX17OrLater));
+  EXPECT_TRUE(notMatches("void baz() { if (1 > 0) {} }", ifStmt(isConstexpr()),
+                         LanguageMode::CXX17OrLater));
 }
 
 TEST(TemplateArgumentCountIs, Matches) {
Index: clang/lib/ASTMatchers/Dynamic/Registry.cpp
===================================================================
--- clang/lib/ASTMatchers/Dynamic/Registry.cpp
+++ clang/lib/ASTMatchers/Dynamic/Registry.cpp
@@ -320,6 +320,7 @@
   REGISTER_MATCHER(hasUnqualifiedDesugaredType);
   REGISTER_MATCHER(hasValueType);
   REGISTER_MATCHER(ifStmt);
+  REGISTER_MATCHER(ignoringElidableConstructorCall);
   REGISTER_MATCHER(ignoringImpCasts);
   REGISTER_MATCHER(ignoringImplicit);
   REGISTER_MATCHER(ignoringParenCasts);
Index: clang/include/clang/ASTMatchers/ASTMatchers.h
===================================================================
--- clang/include/clang/ASTMatchers/ASTMatchers.h
+++ clang/include/clang/ASTMatchers/ASTMatchers.h
@@ -6452,6 +6452,45 @@
   return false;
 }
 
+/// Matches expressions that match InnerMatcher that are possibly wrapped in an
+/// elidable constructor.
+///
+/// In C++17 copy elidable constructors are no longer being
+/// generated in the AST as it is not permitted by the standard. They are
+/// however part of the AST in C++14 and earlier. Therefore, to write a matcher
+/// that works in all language modes, the matcher has to skip elidable
+/// constructor AST nodes if they appear in the AST. This matcher can be used to
+/// skip those elidable constructors.
+///
+/// Given
+///
+/// \code
+/// struct H {};
+/// H G();
+/// void f() {
+///   H D = G();
+/// }
+/// \endcode
+///
+/// ``varDecl(hasInitializer(any(
+///       ignoringElidableMoveConstructorCall(callExpr()),
+///       exprWithCleanups(ignoringElidableMoveConstructorCall(callExpr()))))``
+/// matches ``H D = G()``
+AST_MATCHER_P(Expr, ignoringElidableConstructorCall,
+              ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
+  if (const auto *CtorExpr = dyn_cast<CXXConstructExpr>(&Node)) {
+    if (CtorExpr->isElidable()) {
+      if (const auto *MaterializeTemp =
+              dyn_cast<MaterializeTemporaryExpr>(CtorExpr->getArg(0))) {
+        return InnerMatcher.matches(*MaterializeTemp->GetTemporaryExpr(),
+                                    Finder, Builder);
+      }
+      return InnerMatcher.matches(*CtorExpr, Finder, Builder);
+    }
+  }
+  return InnerMatcher.matches(Node, Finder, Builder);
+}
+
 //----------------------------------------------------------------------------//
 // OpenMP handling.
 //----------------------------------------------------------------------------//
Index: clang/docs/LibASTMatchersReference.html
===================================================================
--- clang/docs/LibASTMatchersReference.html
+++ clang/docs/LibASTMatchersReference.html
@@ -5728,6 +5728,30 @@
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Expr.html";>Expr</a>&gt;</td><td class="name" onclick="toggle('ignoringElidableConstructorCall0')"><a name="ignoringElidableConstructorCall0Anchor">ignoringElidableConstructorCall</a></td><td>ast_matchers::Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Expr.html";>Expr</a>&gt; InnerMatcher</td></tr>
+<tr><td colspan="4" class="doc" id="ignoringElidableConstructorCall0"><pre>Matches expressions that match InnerMatcher that are possibly wrapped in an
+elidable constructor.
+
+In C++17 copy elidable constructors are no longer being
+generated in the AST as it is not permitted by the standard. They are
+however part of the AST in C++14 and earlier. Therefore, to write a matcher
+that works in all language modes, the matcher has to skip elidable
+constructor AST nodes if they appear in the AST. This matcher can be used to
+skip those elidable constructors.
+
+Given
+
+struct H {};
+H G();
+void f() {
+  H D = G();
+}
+
+``varDecl(hasInitializer(any(ignoringElidableMoveConstructorCall(callExpr()),exprWithCleanups(ignoringElidableMoveConstructorCall(callExpr()))))``
+matches ``H D = G()``
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Expr.html";>Expr</a>&gt;</td><td class="name" onclick="toggle('ignoringImpCasts0')"><a name="ignoringImpCasts0Anchor">ignoringImpCasts</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Expr.html";>Expr</a>&gt; InnerMatcher</td></tr>
 <tr><td colspan="4" class="doc" id="ignoringImpCasts0"><pre>Matches expressions that match InnerMatcher after any implicit casts
 are stripped off.
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