[clang-tools-extra] [clang-tidy] add misc-constexpr check (PR #146553)

[Baranov Victor via cfe-commits]

================
@@ -0,0 +1,946 @@
+//===--- UseConstexprCheck.cpp - clang-tidy--------------------------------===//
+//
+// 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 "UseConstexprCheck.h"
+#include "../utils/ASTUtils.h"
+#include "../utils/LexerUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTTypeTraits.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclBase.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/OperationKinds.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersInternal.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/Specifiers.h"
+#include "clang/Basic/TokenKinds.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Support/Casting.h"
+#include <cstddef>
+#include <functional>
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::misc {
+
+namespace {
+AST_MATCHER(FunctionDecl, locationPermitsConstexpr) {
+  const bool IsInMainFile =
+      Finder->getASTContext().getSourceManager().isInMainFile(
+          Node.getLocation());
+
+  if (IsInMainFile && Node.hasExternalFormalLinkage())
+    return false;
+  if (!IsInMainFile && !Node.isInlined())
+    return false;
+
+  return true;
+}
+
+AST_MATCHER(Expr, isCXX11ConstantExpr) {
+  return !Node.isValueDependent() &&
+         Node.isCXX11ConstantExpr(Finder->getASTContext());
+}
+
+AST_MATCHER(DeclaratorDecl, isInMacro) {
+  const SourceRange R =
+      SourceRange(Node.getInnerLocStart(), Node.getLocation());
+
+  return Node.getLocation().isMacroID() || Node.getEndLoc().isMacroID() ||
+         utils::rangeContainsMacroExpansion(
+             R, &Finder->getASTContext().getSourceManager()) ||
+         utils::rangeIsEntirelyWithinMacroArgument(
+             R, &Finder->getASTContext().getSourceManager());
+}
+
+AST_MATCHER(Decl, hasNoRedecl) {
+  // There is always the actual declaration
+  return !Node.redecls().empty() &&
+         std::next(Node.redecls_begin()) == Node.redecls_end();
+}
+
+AST_MATCHER(Decl, allRedeclsInSameFile) {
+  const SourceManager &SM = Finder->getASTContext().getSourceManager();
+  const SourceLocation L = Node.getLocation();
+  for (const Decl *ReDecl : Node.redecls()) {
+    if (!SM.isWrittenInSameFile(L, ReDecl->getLocation()))
+      return false;
+  }
+  return true;
+}
+
+AST_MATCHER(FunctionDecl, isConstexprSpecified) {
+  return Node.isConstexprSpecified();
+}
+
+bool satisfiesConstructorPropertiesUntil20(const CXXConstructorDecl *Ctor,
+                                           ASTContext &Ctx) {
+  const CXXRecordDecl *Rec = Ctor->getParent();
+  llvm::SmallPtrSet<const RecordDecl *, 8> Bases{};
+  for (const CXXBaseSpecifier Base : Rec->bases()) {
+    Bases.insert(Base.getType()->getAsRecordDecl());
+  }
----------------
vbvictor wrote:

```suggestion
  for (const CXXBaseSpecifier Base : Rec->bases())
    Bases.insert(Base.getType()->getAsRecordDecl());
```

https://github.com/llvm/llvm-project/pull/146553