================
@@ -0,0 +1,120 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "RedundantCastingCheck.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/TemplateBase.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/STLExtras.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::llvm_check {
+
+namespace {
+AST_MATCHER(Expr, isMacroID) { return Node.getExprLoc().isMacroID(); }
+AST_MATCHER_P(OverloadExpr, hasAnyUnresolvedName, ArrayRef<StringRef>, Names) {
+ auto DeclName = Node.getName();
+ if (!DeclName.isIdentifier())
+ return false;
+ const IdentifierInfo *II = DeclName.getAsIdentifierInfo();
+ return llvm::any_of(Names, [II](StringRef Name) { return II->isStr(Name); });
+}
+} // namespace
+
+static constexpr StringRef FunctionNames[] = {
+ "cast", "cast_or_null", "cast_if_present",
+ "dyn_cast", "dyn_cast_or_null", "dyn_cast_if_present"};
+
+void RedundantCastingCheck::registerMatchers(MatchFinder *Finder) {
+ auto AnyCalleeName = [](ArrayRef<StringRef> CalleeName) {
+ return allOf(unless(isMacroID()), unless(cxxMemberCallExpr()),
+ callee(expr(ignoringImpCasts(
+ declRefExpr(to(namedDecl(hasAnyName(CalleeName))),
+ hasAnyTemplateArgumentLoc(anything()))
+ .bind("callee")))));
+ };
+ auto AnyCalleeNameInUninstantiatedTemplate =
+ [](ArrayRef<StringRef> CalleeName) {
+ return allOf(unless(isMacroID()), unless(cxxMemberCallExpr()),
+ callee(expr(ignoringImpCasts(
+ unresolvedLookupExpr(hasAnyUnresolvedName(CalleeName))
+ .bind("callee")))));
+ };
+ Finder->addMatcher(callExpr(AnyCalleeName(FunctionNames)).bind("call"),
this);
+ Finder->addMatcher(
+ callExpr(AnyCalleeNameInUninstantiatedTemplate(FunctionNames))
+ .bind("call"),
+ this);
+}
+
+static QualType stripPointerOrReference(QualType Ty) {
+ QualType Pointee = Ty->getPointeeType();
+ if (Pointee.isNull())
+ return Ty;
+ return Pointee;
+}
+
+void RedundantCastingCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto &Nodes = Result.Nodes;
+ const auto *Call = Nodes.getNodeAs<CallExpr>("call");
+ if (Call->getNumArgs() != 1)
+ return;
+
+ CanQualType RetTy;
+ std::string FuncName;
+ if (const auto *ResolvedCallee = Nodes.getNodeAs<DeclRefExpr>("callee")) {
+ const auto *F = cast<FunctionDecl>(ResolvedCallee->getDecl());
+ RetTy = stripPointerOrReference(F->getReturnType())
+ ->getCanonicalTypeUnqualified();
+ FuncName = F->getName();
+ } else if (const auto *UnresolvedCallee =
+ Nodes.getNodeAs<UnresolvedLookupExpr>("callee")) {
+ if (UnresolvedCallee->getNumTemplateArgs() != 1)
+ return;
+ auto TArg = UnresolvedCallee->template_arguments()[0].getArgument();
+ if (TArg.getKind() != TemplateArgument::Type)
+ return;
+
+ RetTy = TArg.getAsType()->getCanonicalTypeUnqualified();
+ FuncName = UnresolvedCallee->getName().getAsString();
+ } else {
+ llvm_unreachable("");
+ }
+
+ const auto *Arg = Call->getArg(0);
+ const CanQualType FromTy =
+ stripPointerOrReference(Arg->getType())->getCanonicalTypeUnqualified();
+ const auto *FromDecl = FromTy->getAsCXXRecordDecl();
+ const auto *RetDecl = RetTy->getAsCXXRecordDecl();
+ const bool IsDerived =
+ FromDecl && RetDecl && FromDecl->isDerivedFrom(RetDecl);
+ if (FromTy != RetTy && !IsDerived)
+ return;
+
+ auto GetText = [&](SourceRange R) {
+ return Lexer::getSourceText(CharSourceRange::getTokenRange(R),
+ *Result.SourceManager, getLangOpts());
+ };
+ StringRef ArgText = GetText(Arg->getSourceRange());
+ diag(Call->getExprLoc(), "redundant use of '%0'")
+ << FuncName
+ << FixItHint::CreateReplacement(Call->getSourceRange(), ArgText);
+ diag(Arg->getExprLoc(), "source expression has type %0", DiagnosticIDs::Note)
+ << Arg->getSourceRange() << Arg->IgnoreParenImpCasts()->getType();
+
+ if (FromTy != RetTy) {
+ diag(Arg->getExprLoc(), "%0 is a subtype of %1", DiagnosticIDs::Note)
+ << FromTy << RetTy;
----------------
localspook wrote:
Two related comments here:
1. Are the `%0` substitutions in these two notes intended to be the same? I
can't tell, because in the first case, we print
`Arg->IgnoreParenImpCasts()->getType()`, but in the second, we print `FromTy`.
2. If they *are* intended to be the same, could we combine the two notes like
so:
```cpp
diag(Arg->getExprLoc(), "source expression has type %0%select{|, which is a
subtype of %2}1", DiagnosticIDs::Note)
<< Arg->getSourceRange() << FromTy << FromTy != RetTy << RetTy;
```
I feel that not repeating the source type makes the diagnostic a bit easier to
read.
https://github.com/llvm/llvm-project/pull/189274
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