Fix two false positives in -Wreturn-stack-address
If the return type is a pointer and the function returns the reference to a
pointer, don't warn since only the value is returned, not the reference.
If a reference function parameter appears in the reference chain, don't warn
since binding happens at the caller scope, so addresses returned are not
to local stack. This includes default arguments as well.
llvm-svn: 277889
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 2ca3d12..fd90121 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6572,6 +6572,12 @@
if (!stackE)
return; // Nothing suspicious was found.
+ // Parameters are initalized in the calling scope, so taking the address
+ // of a parameter reference doesn't need a warning.
+ for (auto *DRE : refVars)
+ if (isa<ParmVarDecl>(DRE->getDecl()))
+ return;
+
SourceLocation diagLoc;
SourceRange diagRange;
if (refVars.empty()) {
@@ -6595,6 +6601,13 @@
} else if (isa<AddrLabelExpr>(stackE)) { // address of label.
S.Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
} else { // local temporary.
+ // If there is an LValue->RValue conversion, then the value of the
+ // reference type is used, not the reference.
+ if (auto *ICE = dyn_cast<ImplicitCastExpr>(RetValExp)) {
+ if (ICE->getCastKind() == CK_LValueToRValue) {
+ return;
+ }
+ }
S.Diag(diagLoc, diag::warn_ret_local_temp_addr_ref)
<< lhsType->isReferenceType() << diagRange;
}