[clang] [clang-tools-extra] [clang-tidy] Add new check `modernize-use-designated-initializers` (PR #80541)

[Julian Schmidt via cfe-commits]

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In-Reply-To: <llvm.org/llvm/llvm-project/pull/80541 at github.com>


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@@ -0,0 +1,43 @@
+//===--- DesignatedInitializers.h -------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utilities for designated initializers.
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/Expr.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/DenseMap.h"
+
+namespace clang::tooling {
+
+/// Get designators describing the elements of a (syntactic) init list.
+///
+/// Given for example the type
+///
+///     struct S { int i, j; };
+///
+/// and the definition
+///
+///     S s{1, 2};
+///
+/// calling `getDesignators` for the initializer list expression `{1, 2}`
+/// would produce the map `{loc(1): ".i", loc(2): ".j"}`.
+///
+/// It does not produce designators for any explicitly-written nested lists,
+/// e.g. `{1, .j=2}` would only return `{loc(1): ".i"}`.
+///
+/// It also considers structs with fields of record types like
+/// `struct T { S s; };`. In this case, there would be designators of the
+/// form
+/// `.s.i` and `.s.j` in the returned map.
+llvm::DenseMap<clang::SourceLocation, std::string>
+getDesignators(const clang::InitListExpr *Syn);
----------------
5chmidti wrote:

I'd suggest renaming this function to `getUnwrittenDesignators` because that is what it does. It does not return existing designators (I know the name comes from the clangd implementation).

https://github.com/llvm/llvm-project/pull/80541