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Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/200166 at github.com>
================
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "ExpensiveValueOrCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::performance {
+
+ExpensiveValueOrCheck::ExpensiveValueOrCheck(StringRef Name,
+ ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ SizeThreshold(Options.get("SizeThreshold", 8U)),
+ WarnOnRvalueOptional(Options.get("WarnOnRvalueOptional", false)),
+ OptionalTypes(utils::options::parseStringList(
+ Options.get("OptionalTypes", "::std::optional"))) {}
+
+void ExpensiveValueOrCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "SizeThreshold", SizeThreshold);
+ Options.store(Opts, "WarnOnRvalueOptional", WarnOnRvalueOptional);
+ Options.store(Opts, "OptionalTypes",
+ utils::options::serializeStringList(OptionalTypes));
+}
+
+void ExpensiveValueOrCheck::registerMatchers(MatchFinder *Finder) {
+ auto OptionalTypesMatcher = hasAnyName(OptionalTypes);
+
+ Finder->addMatcher(
+ cxxMemberCallExpr(callee(cxxMethodDecl(hasName("value_or"),
+ ofClass(OptionalTypesMatcher))))
+ .bind("call"),
+ this);
+}
+
+void ExpensiveValueOrCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call");
+ if (!Call)
+ return;
+
+ const Expr *ObjExpr = Call->getImplicitObjectArgument();
+ if (!WarnOnRvalueOptional && ObjExpr && !ObjExpr->isLValue())
+ return;
+
+ const QualType ValueType = Call->getType().getCanonicalType();
+ if (ValueType->isDependentType() || ValueType->isIncompleteType())
+ return;
+
+ const ASTContext &Ctx = *Result.Context;
+ const int64_t ValueSize = Ctx.getTypeSizeInChars(ValueType).getQuantity();
+ const bool IsExpensive = !ValueType.isTriviallyCopyableType(Ctx) ||
+ ValueSize > static_cast<int64_t>(SizeThreshold);
+
+ if (!IsExpensive)
+ return;
+
+ diag(Call->getExprLoc(),
+ "'value_or' copies expensive type %0; consider using 'operator*' or "
+ "'value()' with a separate fallback")
+ << ValueType;
----------------
zwuis wrote:
In "clang/lib/AST/ASTDiagnostic.cpp", there is a function `ConvertTypeToDiagnosticString` that generates strings like "SugaredType (aka CanonicalType)" for diagnostics, but I'm not sure how to trigger it.
https://github.com/llvm/llvm-project/pull/200166