[ASTMatchers] Add matchers for decomposition decls

[aaron.ballman]

Thanks for this! It generally looks good, aside from some minor nits. Btw, it looks like the HTML documentation wasn't regenerated for the patch.

clang/include/clang/ASTMatchers/ASTMatchers.h

7392

Can you add code examples to all of the new functionality?

7395–7397

clang/lib/ASTMatchers/Dynamic/Registry.cpp

274

This should be kept in alphabetical order.

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

2142–2144

Can you add some test coverage for the invalid cases as well, like asking for an out-of-range binding?

[steveire]

Update

[aaron.ballman]

LGTM!

[thakis]

Looks like this doesn't link on windows: http://45.33.8.238/win/32481/step_4.txt

[steveire]

In D95739#2536515, @thakis wrote:

Looks like this doesn't link on windows: http://45.33.8.238/win/32481/step_4.txt

Thanks, should be fixed now.

[thakis]

Thanks for the quick fix!

clang/include/clang/ASTMatchers/ASTMatchers.h

 ///
 /// \code
 ///   int number = 42;
 ///   auto [foo, bar] = std::make_pair{42, 42};
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Decl, DecompositionDecl>
     decompositionDecl;
 
+/// Matches binding declarations
+/// Example matches \c foo and \c bar
+/// (matcher = bindingDecl()
+///
+/// \code
+///   auto [foo, bar] = std::make_pair{42, 42};
+/// \endcode
+extern const internal::VariadicDynCastAllOfMatcher<Decl, BindingDecl>
+    bindingDecl;
+
 /// Matches a declaration of a linkage specification.
 ///
 /// Given
 /// \code
 ///   extern "C" {}
 /// \endcode
 /// linkageSpecDecl()
 ///   matches "extern "C" {}"

 /// expr(nullPointerConstant())
 ///   matches the initializer for v1, v2, v3, cp, and ip. Does not match the
 ///   initializer for i.
 AST_MATCHER(Expr, nullPointerConstant) {
   return Node.isNullPointerConstant(Finder->getASTContext(),
                                     Expr::NPC_ValueDependentIsNull);
 }
 
+/// Matches the DecompositionDecl the binding belongs to.
+AST_MATCHER_P(BindingDecl, forDecomposition, internal::Matcher<ValueDecl>,
+              InnerMatcher) {
+  if (!Node.getDecomposedDecl())
+    return false;
+  return InnerMatcher.matches(*Node.getDecomposedDecl(), Finder, Builder);
+}
+
+/// Matches the Nth binding of a DecompositionDecl.
+AST_MATCHER_P2(DecompositionDecl, hasBinding, unsigned, N,
+               internal::Matcher<BindingDecl>, InnerMatcher) {
+  if (Node.bindings().size() <= N)
+    return false;
+  return InnerMatcher.matches(*Node.bindings()[N], Finder, Builder);
+}
+
+/// Matches any binding of a DecompositionDecl.
+AST_MATCHER_P(DecompositionDecl, hasAnyBinding, internal::Matcher<BindingDecl>,
+              InnerMatcher) {
+  return llvm::any_of(Node.bindings(), [&](const auto *Binding) {
+    return InnerMatcher.matches(*Binding, Finder, Builder);
+  });
+}
+
 /// Matches declaration of the function the statement belongs to
 ///
 /// Given:
 /// \code
 /// F& operator=(const F& o) {
 ///   std::copy_if(o.begin(), o.end(), begin(), [](V v) { return v > 0; });
 ///   return *this;
 /// }

clang/lib/ASTMatchers/Dynamic/Registry.cpp

RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(asmStmt);
   REGISTER_MATCHER(atomicExpr);
   REGISTER_MATCHER(atomicType);
   REGISTER_MATCHER(autoType);
   REGISTER_MATCHER(autoreleasePoolStmt)
   REGISTER_MATCHER(binaryConditionalOperator);
   REGISTER_MATCHER(binaryOperator);
   REGISTER_MATCHER(binaryOperation);
+  REGISTER_MATCHER(bindingDecl);
   REGISTER_MATCHER(blockDecl);
   REGISTER_MATCHER(blockExpr);
   REGISTER_MATCHER(blockPointerType);
   REGISTER_MATCHER(booleanType);
   REGISTER_MATCHER(breakStmt);
   REGISTER_MATCHER(builtinType);
   REGISTER_MATCHER(cStyleCastExpr);
   REGISTER_MATCHER(callExpr);
RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(enumType);
   REGISTER_MATCHER(equalsBoundNode);
   REGISTER_MATCHER(equalsIntegralValue);
   REGISTER_MATCHER(explicitCastExpr);
   REGISTER_MATCHER(expr);
   REGISTER_MATCHER(exprWithCleanups);
   REGISTER_MATCHER(fieldDecl);
   REGISTER_MATCHER(floatLiteral);
+  REGISTER_MATCHER(forDecomposition);
   REGISTER_MATCHER(forEach);
   REGISTER_MATCHER(forEachArgumentWithParam);
   REGISTER_MATCHER(forEachArgumentWithParamType);
   REGISTER_MATCHER(forEachConstructorInitializer);
   REGISTER_MATCHER(forEachDescendant);
   REGISTER_MATCHER(forEachOverridden);
   REGISTER_MATCHER(forEachSwitchCase);
   REGISTER_MATCHER(forField);
RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(hasAnyTemplateArgument);
   REGISTER_MATCHER(hasAnyUsingShadowDecl);
   REGISTER_MATCHER(hasArgument);
   REGISTER_MATCHER(hasArgumentOfType);
   REGISTER_MATCHER(hasArraySize);
   REGISTER_MATCHER(hasAttr);
   REGISTER_MATCHER(hasAutomaticStorageDuration);
   REGISTER_MATCHER(hasBase);
+  REGISTER_MATCHER(hasAnyBinding);
+  REGISTER_MATCHER(hasBinding);
   REGISTER_MATCHER(hasBitWidth);
   REGISTER_MATCHER(hasBody);
   REGISTER_MATCHER(hasCanonicalType);
   REGISTER_MATCHER(hasCaseConstant);
   REGISTER_MATCHER(hasCastKind);
   REGISTER_MATCHER(hasCondition);
   REGISTER_MATCHER(hasConditionVariableStatement);
   REGISTER_MATCHER(hasDecayedType);

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

StringRef ObjCString = "void f(id obj) {"
                          "}";
 
   EXPECT_TRUE(matchesObjC(ObjCString, objcTryStmt()));
   EXPECT_TRUE(matchesObjC(ObjCString, objcThrowStmt()));
   EXPECT_TRUE(matchesObjC(ObjCString, objcCatchStmt()));
   EXPECT_TRUE(matchesObjC(ObjCString, objcFinallyStmt()));
 }
 
+TEST(ASTMatchersTest, DecompositionDecl) {
+  StringRef Code = R"cpp(
+void foo()
+{
+    int arr[3];
+    auto &[f, s, t] = arr;
+
+    f = 42;
+}
+  )cpp";
+  EXPECT_TRUE(matchesConditionally(
+      Code, decompositionDecl(hasBinding(0, bindingDecl(hasName("f")))), true,
+      {"-std=c++17"}));
+
+  EXPECT_TRUE(matchesConditionally(
+      Code,
+      bindingDecl(decl().bind("self"), hasName("f"),
+                  forDecomposition(decompositionDecl(
+                      hasAnyBinding(bindingDecl(equalsBoundNode("self")))))),
+      true, {"-std=c++17"}));
+}
+
 TEST(ASTMatchersTestObjC, ObjCAutoreleasePoolStmt) {
   StringRef ObjCString = "void f() {"
                          "@autoreleasepool {"
                          "  int x = 1;"
                          "}"
                          "}";
   EXPECT_TRUE(matchesObjC(ObjCString, autoreleasePoolStmt()));
   StringRef ObjCStringNoPool = "void f() { int x = 1; }";