================
@@ -1766,6 +1812,48 @@ fixUPCAddressofArraySubscriptWithSpan(const
UnaryOperator *Node) {
FixItHint::CreateReplacement(Node->getSourceRange(), SS.str())};
}
+std::optional<FixItList>
+UUCAddAssignGadget::getFixits(const Strategy &S) const {
+ DeclUseList DREs = getClaimedVarUseSites();
+
+ if (DREs.size() != 1)
+ return std::nullopt; // In cases of `Ptr += n` where `Ptr` is not a DRE, we
+ // give up
+ if (const VarDecl *VD = dyn_cast<VarDecl>(DREs.front()->getDecl())) {
+ if (S.lookup(VD) == Strategy::Kind::Span) {
+ FixItList Fixes;
+ std::stringstream SS;
+ const Stmt *AddAssignNode = getBaseStmt();
+ StringRef varName = VD->getName();
+ const ASTContext &Ctx = VD->getASTContext();
+
+ if (!isNonNegativeIntegerExpr(Offset, VD, Ctx))
+ return std::nullopt;
+
+ // To transform UUC(p += n) to UUC(p = p.subspan(..)):
+ SS << varName.data() << " = " << varName.data() << ".subspan";
----------------
haoNoQ wrote:
> _"Ironic. We could save others from `.data()` but not ourselves."_
On a serious note though, it looks like `StringRef.data()` is a plain `const
char *` that isn't guaranteed to be null-terminated. And `std::stringstream`
probably expects it to be null-terminated, because there's no other bounds
information available to it. So I'm quite worried about an actual overrun in
this case.
Worth noting that `StringRef.str()` is safer than `StringRef.data()` because it
produces a `std::string`, but of course this requires an unnecessary deep copy.
I think the usual idiom in LLVM is
```
llvm::SmallString<128> Str;
llvm::raw_svector_ostream SS(Str);
SS << varName << ...;
```
because custom streams consume `llvm::StringRef` naturally. Though for such
simple operations I think it's perfectly fine to just use `+`:
```
std::string S = varName.str() + " = " + varName + ".subspan";
if (NotParenExpr)
S += "(";
```
https://github.com/llvm/llvm-project/pull/71862
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