[clang-tools-extra] [clangd] Add tweak to abbreviate function templates (PR #74710)

[Jeremy Stucki via cfe-commits]

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@@ -0,0 +1,352 @@
+//===-- AbbreviateFunctionTemplate.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 "FindTarget.h"
+#include "SourceCode.h"
+#include "XRefs.h"
+#include "refactor/Tweak.h"
+#include "support/Logger.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ExprConcepts.h"
+#include "clang/Tooling/Core/Replacement.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Error.h"
+#include <numeric>
+
+namespace clang {
+namespace clangd {
+namespace {
+/// Converts a function template to its abbreviated form using auto parameters.
+/// Before:
+///     template <std::integral T>
+///     auto foo(T param) { }
+///          ^^^^^^^^^^^
+/// After:
+///     auto foo(std::integral auto param) { }
+class AbbreviateFunctionTemplate : public Tweak {
+public:
+  const char *id() const final;
+
+  auto prepare(const Selection &Inputs) -> bool override;
+  auto apply(const Selection &Inputs) -> Expected<Effect> override;
+
+  auto title() const -> std::string override {
+    return llvm::formatv("Abbreviate function template");
+  }
+
+  auto kind() const -> llvm::StringLiteral override {
+    return CodeAction::REFACTOR_KIND;
+  }
+
+private:
+  static const char *AutoKeywordSpelling;
+  const FunctionTemplateDecl *FunctionTemplateDeclaration;
+
+  struct TemplateParameterInfo {
+    const TypeConstraint *Constraint;
+    unsigned int FunctionParameterIndex;
+    std::vector<tok::TokenKind> FunctionParameterQualifiers;
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jeremystucki wrote:

Oh I didn't know about that. Done in https://github.com/llvm/llvm-project/pull/74710/commits/d38f61e8cfbfbd066fca23f38a4015f2612bee86.

https://github.com/llvm/llvm-project/pull/74710