[ASTMatchers] Add matchers for decomposition decls

Differential Revision: https://reviews.llvm.org/D95739

clang/docs/LibASTMatchersReference.html

@@ -591,6 +591,15 @@ accessSpecDecl()
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('bindingDecl0')"><a name="bindingDecl0Anchor">bindingDecl</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BindingDecl.html">BindingDecl</a>&gt;...</td></tr>
+<tr><td colspan="4" class="doc" id="bindingDecl0"><pre>Matches binding declarations
+Example matches foo and bar
+(matcher = bindingDecl()
+
+  auto [foo, bar] = std::make_pair{42, 42};
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('blockDecl0')"><a name="blockDecl0Anchor">blockDecl</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BlockDecl.html">BlockDecl</a>&gt;...</td></tr>
 <tr><td colspan="4" class="doc" id="blockDecl0"><pre>Matches block declarations.
 
@@ -6011,6 +6020,24 @@ Example matches b (matcher = binaryOperator(hasRHS()))
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BindingDecl.html">BindingDecl</a>&gt;</td><td class="name" onclick="toggle('forDecomposition0')"><a name="forDecomposition0Anchor">forDecomposition</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ValueDecl.html">ValueDecl</a>&gt; InnerMatcher</td></tr>
+<tr><td colspan="4" class="doc" id="forDecomposition0"><pre>Matches the DecompositionDecl the binding belongs to.
+
+For example, in:
+void foo()
+{
+    int arr[3];
+    auto &amp;[f, s, t] = arr;
+
+    f = 42;
+}
+The matcher:
+  bindingDecl(hasName("f"),
+                forDecomposition(decompositionDecl())
+matches 'f' in 'auto &amp;[f, s, t]'.
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BlockDecl.html">BlockDecl</a>&gt;</td><td class="name" onclick="toggle('hasAnyParameter2')"><a name="hasAnyParameter2Anchor">hasAnyParameter</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1ParmVarDecl.html">ParmVarDecl</a>&gt; InnerMatcher</td></tr>
 <tr><td colspan="4" class="doc" id="hasAnyParameter2"><pre>Matches any parameter of a function or an ObjC method declaration or a
 block.
@@ -7090,6 +7117,40 @@ Usable as: Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Decl
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1DecompositionDecl.html">DecompositionDecl</a>&gt;</td><td class="name" onclick="toggle('hasAnyBinding0')"><a name="hasAnyBinding0Anchor">hasAnyBinding</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BindingDecl.html">BindingDecl</a>&gt; InnerMatcher</td></tr>
+<tr><td colspan="4" class="doc" id="hasAnyBinding0"><pre>Matches any binding of a DecompositionDecl.
+
+For example, in:
+void foo()
+{
+    int arr[3];
+    auto &amp;[f, s, t] = arr;
+
+    f = 42;
+}
+The matcher:
+  decompositionDecl(hasAnyBinding(bindingDecl(hasName("f").bind("fBinding"))))
+matches the decomposition decl with 'f' bound to "fBinding".
+</pre></td></tr>
+
+
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1DecompositionDecl.html">DecompositionDecl</a>&gt;</td><td class="name" onclick="toggle('hasBinding0')"><a name="hasBinding0Anchor">hasBinding</a></td><td>unsigned N, Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BindingDecl.html">BindingDecl</a>&gt; InnerMatcher</td></tr>
+<tr><td colspan="4" class="doc" id="hasBinding0"><pre>Matches the Nth binding of a DecompositionDecl.
+
+For example, in:
+void foo()
+{
+    int arr[3];
+    auto &amp;[f, s, t] = arr;
+
+    f = 42;
+}
+The matcher:
+  decompositionDecl(hasBinding(0, bindingDecl(hasName("f").bind("fBinding"))))
+matches the decomposition decl with 'f' bound to "fBinding".
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1DoStmt.html">DoStmt</a>&gt;</td><td class="name" onclick="toggle('hasBody0')"><a name="hasBody0Anchor">hasBody</a></td><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt; InnerMatcher</td></tr>
 <tr><td colspan="4" class="doc" id="hasBody0"><pre></pre></td></tr>
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -347,6 +347,16 @@ extern const internal::VariadicAllOfMatcher<Decl> decl;
 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
@@ -7379,6 +7389,80 @@ AST_MATCHER(Expr, nullPointerConstant) {
                                     Expr::NPC_ValueDependentIsNull);
 }
 
+/// Matches the DecompositionDecl the binding belongs to.
+///
+/// For example, in:
+/// \code
+/// void foo()
+/// {
+///     int arr[3];
+///     auto &[f, s, t] = arr;
+///
+///     f = 42;
+/// }
+/// \endcode
+/// The matcher:
+/// \code
+///   bindingDecl(hasName("f"),
+///                 forDecomposition(decompositionDecl())
+/// \endcode
+/// matches 'f' in 'auto &[f, s, t]'.
+AST_MATCHER_P(BindingDecl, forDecomposition, internal::Matcher<ValueDecl>,
+              InnerMatcher) {
+  if (const ValueDecl *VD = Node.getDecomposedDecl())
+    return InnerMatcher.matches(*VD, Finder, Builder);
+  return false;
+}
+
+/// Matches the Nth binding of a DecompositionDecl.
+///
+/// For example, in:
+/// \code
+/// void foo()
+/// {
+///     int arr[3];
+///     auto &[f, s, t] = arr;
+///
+///     f = 42;
+/// }
+/// \endcode
+/// The matcher:
+/// \code
+///   decompositionDecl(hasBinding(0,
+///   bindingDecl(hasName("f").bind("fBinding"))))
+/// \endcode
+/// matches the decomposition decl with 'f' bound to "fBinding".
+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.
+///
+/// For example, in:
+/// \code
+/// void foo()
+/// {
+///     int arr[3];
+///     auto &[f, s, t] = arr;
+///
+///     f = 42;
+/// }
+/// \endcode
+/// The matcher:
+/// \code
+///   decompositionDecl(hasAnyBinding(bindingDecl(hasName("f").bind("fBinding"))))
+/// \endcode
+/// matches the decomposition decl with 'f' bound to "fBinding".
+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:

clang/lib/ASTMatchers/Dynamic/Registry.cpp

@@ -144,6 +144,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(binaryConditionalOperator);
   REGISTER_MATCHER(binaryOperator);
   REGISTER_MATCHER(binaryOperation);
+  REGISTER_MATCHER(bindingDecl);
   REGISTER_MATCHER(blockDecl);
   REGISTER_MATCHER(blockExpr);
   REGISTER_MATCHER(blockPointerType);
@@ -226,6 +227,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(exprWithCleanups);
   REGISTER_MATCHER(fieldDecl);
   REGISTER_MATCHER(floatLiteral);
+  REGISTER_MATCHER(forDecomposition);
   REGISTER_MATCHER(forEach);
   REGISTER_MATCHER(forEachArgumentWithParam);
   REGISTER_MATCHER(forEachArgumentWithParamType);
@@ -248,6 +250,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(hasAncestor);
   REGISTER_MATCHER(hasAnyArgument);
   REGISTER_MATCHER(hasAnyBase);
+  REGISTER_MATCHER(hasAnyBinding);
   REGISTER_MATCHER(hasAnyClause);
   REGISTER_MATCHER(hasAnyConstructorInitializer);
   REGISTER_MATCHER(hasAnyDeclaration);
@@ -266,6 +269,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(hasAttr);
   REGISTER_MATCHER(hasAutomaticStorageDuration);
   REGISTER_MATCHER(hasBase);
+  REGISTER_MATCHER(hasBinding);
   REGISTER_MATCHER(hasBitWidth);
   REGISTER_MATCHER(hasBody);
   REGISTER_MATCHER(hasCanonicalType);

clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp

@@ -2129,6 +2129,37 @@ TEST(ASTMatchersTestObjC, ObjCExceptionStmts) {
   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_FALSE(matchesConditionally(
+      Code, decompositionDecl(hasBinding(42, bindingDecl(hasName("f")))), true,
+      {"-std=c++17"}));
+  EXPECT_FALSE(matchesConditionally(
+      Code, decompositionDecl(hasBinding(0, bindingDecl(hasName("s")))), true,
+      {"-std=c++17"}));
+  EXPECT_TRUE(matchesConditionally(
+      Code, decompositionDecl(hasBinding(1, bindingDecl(hasName("s")))), 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 {"