mizvekov updated this revision to Diff 333925.
mizvekov added a comment.
Small update making some invariants more clear, with some simplifications.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D99005/new/
https://reviews.llvm.org/D99005
Files:
clang/include/clang/Sema/Sema.h
clang/lib/Sema/Sema.cpp
clang/lib/Sema/SemaCoroutine.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/lib/Sema/SemaStmt.cpp
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
clang/lib/Sema/SemaType.cpp
clang/test/CXX/class/class.init/class.copy.elision/p3.cpp
clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
clang/test/CXX/drs/dr3xx.cpp
clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4-cxx14.cpp
clang/test/CXX/temp/temp.decls/temp.mem/p5.cpp
clang/test/SemaCXX/constant-expression-cxx11.cpp
clang/test/SemaCXX/constant-expression-cxx14.cpp
clang/test/SemaCXX/coroutine-rvo.cpp
clang/test/SemaCXX/coroutines.cpp
clang/test/SemaCXX/deduced-return-type-cxx14.cpp
clang/test/SemaCXX/return-stack-addr.cpp
clang/test/SemaCXX/warn-return-std-move.cpp
Index: clang/test/SemaCXX/warn-return-std-move.cpp
===================================================================
--- clang/test/SemaCXX/warn-return-std-move.cpp
+++ clang/test/SemaCXX/warn-return-std-move.cpp
@@ -1,8 +1,8 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=cxx20_2b -fcxx-exceptions -Wreturn-std-move %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=cxx20_2b -fcxx-exceptions -Wreturn-std-move %s
-// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=cxx20_2b,cxx2b -fcxx-exceptions -Wreturn-std-move %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=cxx20_2b -fcxx-exceptions -Wreturn-std-move %s
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=cxx11_17 -fcxx-exceptions -Wreturn-std-move %s
// RUN: %clang_cc1 -std=c++17 -fsyntax-only -fcxx-exceptions -Wreturn-std-move -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s -check-prefix=CHECK
// RUN: %clang_cc1 -std=c++14 -fsyntax-only -fcxx-exceptions -Wreturn-std-move -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s -check-prefix=CHECK
@@ -217,8 +217,8 @@
}
// But if the return type is a reference type, then moving would be wrong.
-Derived& testRetRef1(Derived&& d) { return d; }
-Base& testRetRef2(Derived&& d) { return d; }
+Derived &testRetRef1(Derived &&d) { return d; } // cxx2b-error {{on-const lvalue reference to type 'Derived' cannot bind to a temporary of type 'Derived'}}
+Base &testRetRef2(Derived &&d) { return d; } // cxx2b-error {{non-const lvalue reference to type 'Base' cannot bind to a temporary of type 'Derived'}}
#if __cplusplus >= 201402L
auto&& testRetRef3(Derived&& d) { return d; }
decltype(auto) testRetRef4(Derived&& d) { return (d); }
Index: clang/test/SemaCXX/return-stack-addr.cpp
===================================================================
--- clang/test/SemaCXX/return-stack-addr.cpp
+++ clang/test/SemaCXX/return-stack-addr.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected %s
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=expected,cxx11 %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx2b %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx11_20 %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=expected,cxx11_20,cxx11 %s
int* ret_local() {
int x = 1;
@@ -29,7 +29,8 @@
int& ret_local_ref() {
int x = 1;
- return x; // expected-warning {{reference to stack memory}}
+ return x; // cxx11_20-warning {{reference to stack memory}}
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
}
int* ret_local_addrOf() {
@@ -154,8 +155,10 @@
(void) [&]() -> int& { return b; };
(void) [=]() mutable -> int& { return a; };
(void) [=]() mutable -> int& { return b; };
- (void) [&]() -> int& { int a; return a; }; // expected-warning {{reference to stack}}
- (void) [=]() -> int& { int a; return a; }; // expected-warning {{reference to stack}}
+ (void) [&]() -> int& { int a; return a; }; // cxx11_20-warning {{reference to stack}}
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
+ (void) [=]() -> int& { int a; return a; }; // cxx11_20-warning {{reference to stack}}
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
(void) [&]() -> int& { int &a = b; return a; };
(void) [=]() mutable -> int& { int &a = b; return a; };
Index: clang/test/SemaCXX/deduced-return-type-cxx14.cpp
===================================================================
--- clang/test/SemaCXX/deduced-return-type-cxx14.cpp
+++ clang/test/SemaCXX/deduced-return-type-cxx14.cpp
@@ -1,11 +1,11 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b %s
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b,cxx2b %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b,cxx2b %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_2b %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_2b %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14 %s
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20,cxx14 %s
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20,cxx14 %s -fdelayed-template-parsing -DDELAYED_TEMPLATE_PARSING
auto f(); // expected-note {{previous}}
int f(); // expected-error {{differ only in their return type}}
@@ -129,10 +129,14 @@
return T() + 1;
}
template<typename T> auto &f2(T &&v) { return v; }
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
+ // cxx2b-error@-2 {{non-const lvalue reference to type 'double' cannot bind to a temporary of type 'double'}}
+ // cxx2b-note@-3 {{candidate template ignored: substitution failure [with T = double]}}
int a = f1<int>();
- const int &b = f2(0);
+ const int &b = f2(0); // cxx2b-note {{in instantiation of function template specialization 'Templates::f2<int>' requested here}}
double d;
float &c = f2(0.0); // expected-error {{non-const lvalue reference to type 'float' cannot bind to a value of unrelated type 'double'}}
+ // cxx2b-note@-1 {{in instantiation of function template specialization 'Templates::f2<double>' requested here}}
template<typename T> auto fwd_decl(); // expected-note {{declared here}}
int e = fwd_decl<int>(); // expected-error {{cannot be used before it is defined}}
@@ -145,8 +149,9 @@
auto (*p)() = f1; // expected-error {{incompatible initializer}}
auto (*q)() = f1<int>; // ok
- typedef decltype(f2(1.2)) dbl; // expected-note {{previous}}
- typedef float dbl; // expected-error {{typedef redefinition with different types ('float' vs 'decltype(f2(1.2))' (aka 'double &'))}}
+ typedef decltype(f2(1.2)) dbl; // cxx14_20-note {{previous}}
+ // cxx2b-error@-1 {{no matching function for call to 'f2'}}
+ typedef float dbl; // cxx14_20-error {{typedef redefinition with different types ('float' vs 'decltype(f2(1.2))' (aka 'double &'))}}
extern template auto fwd_decl<double>();
int k1 = fwd_decl<double>();
Index: clang/test/SemaCXX/coroutines.cpp
===================================================================
--- clang/test/SemaCXX/coroutines.cpp
+++ clang/test/SemaCXX/coroutines.cpp
@@ -1,9 +1,9 @@
// This file contains references to sections of the Coroutines TS, which can be
// found at http://wg21.link/coroutines.
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -fexceptions -Wunused-result
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -fexceptions -Wunused-result
-// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -fsyntax-only -verify=expected %s -fcxx-exceptions -fexceptions -Wunused-result
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b,cxx2b %s -fcxx-exceptions -fexceptions -Wunused-result
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_2b %s -fcxx-exceptions -fexceptions -Wunused-result
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -fsyntax-only -verify=expected,cxx14_20 %s -fcxx-exceptions -fexceptions -Wunused-result
void no_coroutine_traits_bad_arg_await() {
co_await a; // expected-error {{include <experimental/coroutine>}}
@@ -934,7 +934,8 @@
};
extern "C" int f(mismatch_gro_type_tag2) {
- // expected-error@-1 {{cannot initialize return object of type 'int' with an lvalue of type 'void *'}}
+ // cxx2b-error@-1 {{cannot initialize return object of type 'int' with an rvalue of type 'void *'}}
+ // cxx14_20-error@-2 {{cannot initialize return object of type 'int' with an lvalue of type 'void *'}}
co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}
Index: clang/test/SemaCXX/coroutine-rvo.cpp
===================================================================
--- clang/test/SemaCXX/coroutine-rvo.cpp
+++ clang/test/SemaCXX/coroutine-rvo.cpp
@@ -46,7 +46,7 @@
struct NoCopyNoMove {
NoCopyNoMove() = default;
- NoCopyNoMove(const NoCopyNoMove &) = delete; // expected-note 4{{'NoCopyNoMove' has been explicitly marked deleted here}}
+ NoCopyNoMove(const NoCopyNoMove &) = delete;
};
template <typename T>
@@ -62,13 +62,12 @@
task<NoCopyNoMove> local2val() {
NoCopyNoMove value;
- co_return value; // expected-error {{call to deleted constructor of 'NoCopyNoMove'}}
- // expected-error@-1 {{value reference to type 'NoCopyNoMove' cannot bind to lvalue of type 'NoCopyNoMove'}}
+ co_return value;
}
task<NoCopyNoMove &> local2ref() {
NoCopyNoMove value;
- co_return value; // expected-error {{call to deleted constructor of 'NoCopyNoMove'}}
+ co_return value; // expected-error {{non-const lvalue reference to type 'NoCopyNoMove' cannot bind to a temporary of type 'NoCopyNoMove'}}
}
// We need the move constructor for construction of the coroutine.
@@ -81,8 +80,7 @@
}
task<NoCopyNoMove> rvalue2val(NoCopyNoMove &&value) {
- co_return value; // expected-error {{rvalue reference to type 'NoCopyNoMove' cannot bind to lvalue of type 'NoCopyNoMove'}}
- // expected-error@-1 {{call to deleted constructor of 'NoCopyNoMove'}}
+ co_return value;
}
task<NoCopyNoMove &> lvalue2ref(NoCopyNoMove &value) {
@@ -90,7 +88,7 @@
}
task<NoCopyNoMove &> rvalue2ref(NoCopyNoMove &&value) {
- co_return value; // expected-error {{call to deleted constructor of 'NoCopyNoMove'}}
+ co_return value; // expected-error {{non-const lvalue reference to type 'NoCopyNoMove' cannot bind to a temporary of type 'NoCopyNoMove'}}
}
struct To {
Index: clang/test/SemaCXX/constant-expression-cxx14.cpp
===================================================================
--- clang/test/SemaCXX/constant-expression-cxx14.cpp
+++ clang/test/SemaCXX/constant-expression-cxx14.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14 %s -fcxx-exceptions -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b,cxx2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20,cxx20_2b %s -fcxx-exceptions -triple=x86_64-linux-gnu
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20,cxx14 %s -fcxx-exceptions -triple=x86_64-linux-gnu
struct S {
// dummy ctor to make this a literal type
@@ -269,16 +269,23 @@
namespace incdec {
template<typename T> constexpr T &ref(T &&r) { return r; }
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
template<typename T> constexpr T postinc(T &&r) { return (r++, r); }
template<typename T> constexpr T postdec(T &&r) { return (r--, r); }
+ template int &ref<int>(int &&);
+ // cxx2b-note@-1 {{in instantiation of function template specialization}}
+
+ static_assert(postinc(0) == 1, "");
+ static_assert(postdec(0) == -1, "");
+#if __cplusplus <= 202002L
static_assert(++ref(0) == 1, "");
static_assert(ref(0)++ == 0, "");
- static_assert(postinc(0) == 1, "");
static_assert(--ref(0) == -1, "");
static_assert(ref(0)-- == 0, "");
- static_assert(postdec(0) == -1, "");
+#endif
+#if __cplusplus <= 202002L
constexpr int overflow_int_inc_1 = ref(0x7fffffff)++; // expected-error {{constant}} expected-note {{2147483648}}
constexpr int overflow_int_inc_1_ok = ref(0x7ffffffe)++;
constexpr int overflow_int_inc_2 = ++ref(0x7fffffff); // expected-error {{constant}} expected-note {{2147483648}}
@@ -293,33 +300,38 @@
// cxx20_2b-error@-1 {{ISO C++17 does not allow incrementing expression of type bool}}
static_assert(++ref(true), ""); // cxx14-warning {{deprecated}}
// cxx20_2b-error@-1 {{ISO C++17 does not allow incrementing expression of type bool}}
+#endif
int arr[10];
+ static_assert(postinc(&arr[0]) == &arr[1], "");
+ static_assert(postdec(&arr[1]) == &arr[0], "");
+#if __cplusplus <= 202002L
static_assert(++ref(&arr[0]) == &arr[1], "");
static_assert(++ref(&arr[9]) == &arr[10], "");
static_assert(++ref(&arr[10]) == &arr[11], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
static_assert(ref(&arr[0])++ == &arr[0], "");
static_assert(ref(&arr[10])++ == &arr[10], ""); // expected-error {{constant}} expected-note {{cannot refer to element 11}}
- static_assert(postinc(&arr[0]) == &arr[1], "");
static_assert(--ref(&arr[10]) == &arr[9], "");
static_assert(--ref(&arr[1]) == &arr[0], "");
static_assert(--ref(&arr[0]) != &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
static_assert(ref(&arr[1])-- == &arr[1], "");
static_assert(ref(&arr[0])-- == &arr[0], ""); // expected-error {{constant}} expected-note {{cannot refer to element -1}}
- static_assert(postdec(&arr[1]) == &arr[0], "");
+#endif
+ static_assert(postinc(0.0) == 1.0, "");
+ static_assert(postdec(0.0) == -1.0, "");
+#if __cplusplus <= 202002L
int x;
static_assert(++ref(&x) == &x + 1, "");
static_assert(++ref(0.0) == 1.0, "");
static_assert(ref(0.0)++ == 0.0, "");
- static_assert(postinc(0.0) == 1.0, "");
static_assert(--ref(0.0) == -1.0, "");
static_assert(ref(0.0)-- == 0.0, "");
- static_assert(postdec(0.0) == -1.0, "");
static_assert(++ref(1e100) == 1e100, "");
static_assert(--ref(1e100) == 1e100, "");
+#endif
union U {
int a, b;
@@ -861,9 +873,13 @@
namespace Lifetime {
constexpr int &get(int &&r) { return r; }
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
+ // cxx2b-error@-2 {{no return statement in constexpr function}} See PR40598
constexpr int f() {
int &r = get(123);
- return r; // expected-note {{read of object outside its lifetime}}
+ return r;
+ // cxx2b-note@-1 {{use of reference outside its lifetime is not allowed in a constant expression}}
+ // cxx14_20-note@-2 {{read of object outside its lifetime}}
}
static_assert(f() == 123, ""); // expected-error {{constant expression}} expected-note {{in call}}
Index: clang/test/SemaCXX/constant-expression-cxx11.cpp
===================================================================
--- clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx20_2b -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=expected,cxx11 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx20_2b,cxx2b -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx11_20,cxx20_2b -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=expected,cxx11_20,cxx11 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
namespace StaticAssertFoldTest {
@@ -1936,13 +1936,18 @@
}
constexpr int &get(int &&n) { return n; }
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
+ // cxx2b-error@-2 {{no return statement in constexpr function}} See PR40598
constexpr int &&get_rv(int &&n) { return static_cast<int&&>(n); }
struct S {
int &&r;
int &s;
int t;
constexpr S() : r(get_rv(0)), s(get(0)), t(r) {} // expected-note {{read of object outside its lifetime}}
- constexpr S(int) : r(get_rv(0)), s(get(0)), t(s) {} // expected-note {{read of object outside its lifetime}}
+ constexpr S(int) : r(get_rv(0)), s(get(0)), t(s) {}
+ // cxx2b-warning@-1 {{reference 's' is not yet bound to a value when used here}}
+ // cxx2b-note@-2 {{read of uninitialized object is not allowed in a constant expression}}
+ // cxx11_20-note@-3 {{read of object outside its lifetime}}
};
constexpr int k1 = S().t; // expected-error {{constant expression}} expected-note {{in call}}
constexpr int k2 = S(0).t; // expected-error {{constant expression}} expected-note {{in call}}
Index: clang/test/CXX/temp/temp.decls/temp.mem/p5.cpp
===================================================================
--- clang/test/CXX/temp/temp.decls/temp.mem/p5.cpp
+++ clang/test/CXX/temp/temp.decls/temp.mem/p5.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -std=c++98 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx2b %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx98_20 %s
+// RUN: %clang_cc1 -std=c++98 -fsyntax-only -verify=expected,cxx98_20 %s
struct A {
template <class T> operator T*();
@@ -66,8 +66,10 @@
template<typename T> operator const T*() const {
T x = T();
- return x; // expected-error{{cannot initialize return object of type 'const char *' with an lvalue of type 'char'}} \
- // expected-error{{cannot initialize return object of type 'const int *' with an lvalue of type 'int'}}
+ return x; // cxx98_20-error{{cannot initialize return object of type 'const char *' with an lvalue of type 'char'}} \
+ // cxx98_20-error{{cannot initialize return object of type 'const int *' with an lvalue of type 'int'}} \
+ // cxx2b-error{{cannot initialize return object of type 'const char *' with an rvalue of type 'char'}} \
+ // cxx2b-error{{cannot initialize return object of type 'const int *' with an rvalue of type 'int'}}
}
};
Index: clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4-cxx14.cpp
===================================================================
--- clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4-cxx14.cpp
+++ clang/test/CXX/expr/expr.prim/expr.prim.lambda/p4-cxx14.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx2b %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx14_20 %s
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify=expected,cxx14_20 %s
int a;
int &b = [] (int &r) -> decltype(auto) { return r; } (a);
@@ -9,13 +9,15 @@
int &e = [] (int &r) -> auto { return r; } (a); // expected-error {{cannot bind to a temporary}}
int &f = [] (int r) -> decltype(auto) { return r; } (a); // expected-error {{cannot bind to a temporary}}
int &g = [] (int r) -> decltype(auto) { return (r); } (a); // expected-warning {{reference to stack}}
+// cxx2b-error@-1 {{on-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
int test_explicit_auto_return()
{
struct X {};
auto L = [](auto F, auto a) { return F(a); };
auto M = [](auto a) -> auto { return a; }; // OK
- auto MRef = [](auto b) -> auto& { return b; }; //expected-warning{{reference to stack}}
+ auto MRef = [](auto b) -> auto & { return b; }; //cxx14_20-warning{{reference to stack}}
+ // cxx2b-error@-1 {{non-const lvalue reference to type 'X' cannot bind to a temporary of type 'X'}}
auto MPtr = [](auto c) -> auto* { return &c; }; //expected-warning{{address of stack}}
auto MDeclType = [](auto&& d) -> decltype(auto) { return static_cast<decltype(d)>(d); }; //OK
M(3);
Index: clang/test/CXX/drs/dr3xx.cpp
===================================================================
--- clang/test/CXX/drs/dr3xx.cpp
+++ clang/test/CXX/drs/dr3xx.cpp
@@ -1,9 +1,9 @@
-// RUN: %clang_cc1 -std=c++2b -verify=expected,cxx20_2b -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++20 -verify=expected,cxx20_2b -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++17 -verify=expected,cxx98_17 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 -verify=expected,cxx98_17 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 -verify=expected,cxx98_17 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++98 -verify=expected,cxx98_17 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2b -verify=expected,cxx20_2b,cxx2b -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 -verify=expected,cxx98_20,cxx20_2b -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 -verify=expected,cxx98_17,cxx98_20 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -verify=expected,cxx98_17,cxx98_20 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 -verify=expected,cxx98_17,cxx98_20 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 -verify=expected,cxx98_17,cxx98_20 -triple %itanium_abi_triple %s -fexceptions -fcxx-exceptions -pedantic-errors
namespace dr300 { // dr300: yes
template<typename R, typename A> void f(R (&)(A)) {}
@@ -628,7 +628,8 @@
struct A {
template <class T> operator T ***() {
int ***p = 0;
- return p; // expected-error {{cannot initialize return object of type 'const int ***' with an lvalue of type 'int ***'}}
+ return p; // cxx98_20-error {{cannot initialize return object of type 'const int ***' with an lvalue of type 'int ***'}}
+ // cxx2b-error@-1 {{cannot initialize return object of type 'const int ***' with an rvalue of type 'int ***'}}
}
};
Index: clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
===================================================================
--- clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
+++ clang/test/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/p7-cxx14.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -verify -std=c++2b -verify %s
-// RUN: %clang_cc1 -verify -std=c++20 -verify %s
-// RUN: %clang_cc1 -verify -std=c++14 -verify %s
+// RUN: %clang_cc1 -verify -std=c++2b -verify=expected,cxx2b %s
+// RUN: %clang_cc1 -verify -std=c++20 -verify=expected,cxx14_20 %s
+// RUN: %clang_cc1 -verify -std=c++14 -verify=expected,cxx14_20 %s
namespace std {
template<typename T> struct initializer_list {
@@ -30,7 +30,7 @@
auto x4a = (i);
decltype(auto) x4d = (i);
using Int = decltype(x4a);
-using IntLRef = decltype(x4d);
+using IntLRef = decltype(x4d); // cxx2b-note {{previous definition is here}}
auto x5a = f();
decltype(auto) x5d = f();
@@ -81,7 +81,7 @@
auto f3a(int n) { return (n); }
decltype(auto) f3d(int n) { return (n); } // expected-warning {{reference to stack memory}}
using Int = decltype(f3a(0));
-using IntLRef = decltype(f3d(0));
+using IntLRef = decltype(f3d(0)); // cxx2b-error {{type alias redefinition with different types ('decltype(f3d(0))' (aka 'int &&') vs 'decltype(x4d)' (aka 'int &'))}}
auto f4a(int n) { return f(); }
decltype(auto) f4d(int n) { return f(); }
@@ -91,7 +91,7 @@
auto f5aa(int n) { auto x = f(); return x; }
auto f5ad(int n) { decltype(auto) x = f(); return x; }
decltype(auto) f5da(int n) { auto x = f(); return x; }
-decltype(auto) f5dd(int n) { decltype(auto) x = f(); return x; } // expected-error {{rvalue reference to type 'int' cannot bind to lvalue}}
+decltype(auto) f5dd(int n) { decltype(auto) x = f(); return x; } // cxx14_20-error {{rvalue reference to type 'int' cannot bind to lvalue}}
using Int = decltype(f5aa(0));
using Int = decltype(f5ad(0));
using Int = decltype(f5da(0));
Index: clang/test/CXX/class/class.init/class.copy.elision/p3.cpp
===================================================================
--- clang/test/CXX/class/class.init/class.copy.elision/p3.cpp
+++ clang/test/CXX/class/class.init/class.copy.elision/p3.cpp
@@ -1,8 +1,8 @@
-// RUN: %clang_cc1 -std=c++2b -fsyntax-only -fcxx-exceptions -verify=expected,cxx20_2b %s
-// RUN: %clang_cc1 -std=c++20 -fsyntax-only -fcxx-exceptions -verify=expected,cxx20_2b %s
-// RUN: %clang_cc1 -std=c++17 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17 %s
-// RUN: %clang_cc1 -std=c++14 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17 %s
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17 %s
+// RUN: %clang_cc1 -std=c++2b -fsyntax-only -fcxx-exceptions -verify=expected,cxx20_2b,cxx2b %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_20,cxx20_2b %s
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17,cxx11_20 %s
+// RUN: %clang_cc1 -std=c++14 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17,cxx11_20 %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fcxx-exceptions -verify=expected,cxx11_17,cxx11_20 %s
namespace test_delete_function {
struct A1 {
@@ -409,8 +409,10 @@
namespace test_simpler_implicit_move {
struct CopyOnly {
- CopyOnly();
- CopyOnly(CopyOnly &);
+ CopyOnly(); // cxx2b-note {{candidate constructor not viable: requires 0 arguments, but 1 was provided}}
+ // cxx2b-note@-1 {{candidate constructor not viable: requires 0 arguments, but 1 was provided}}
+ CopyOnly(CopyOnly &); // cxx2b-note {{candidate constructor not viable: expects an lvalue for 1st argument}}
+ // cxx2b-note@-1 {{candidate constructor not viable: expects an lvalue for 1st argument}}
};
struct MoveOnly {
MoveOnly();
@@ -419,7 +421,7 @@
MoveOnly &&rref();
MoveOnly &&test1(MoveOnly &&w) {
- return w; // expected-error {{cannot bind to lvalue of type}}
+ return w; // cxx11_20-error {{cannot bind to lvalue of type}}
}
CopyOnly test2(bool b) {
@@ -428,22 +430,22 @@
if (b) {
return w1;
} else {
- return w2;
+ return w2; // cxx2b-error {{no matching constructor for initialization}}
}
}
-template <class T> T &&test3(T &&x) { return x; } // expected-error {{cannot bind to lvalue of type}}
+template <class T> T &&test3(T &&x) { return x; } // cxx11_20-error {{cannot bind to lvalue of type}}
template MoveOnly& test3<MoveOnly&>(MoveOnly&);
-template MoveOnly&& test3<MoveOnly>(MoveOnly&&); // expected-note {{in instantiation of function template specialization}}
+template MoveOnly &&test3<MoveOnly>(MoveOnly &&); // cxx11_20-note {{in instantiation of function template specialization}}
MoveOnly &&test4() {
MoveOnly &&x = rref();
- return x; // expected-error {{cannot bind to lvalue of type}}
+ return x; // cxx11_20-error {{cannot bind to lvalue of type}}
}
void test5() try {
CopyOnly x;
- throw x;
+ throw x; // cxx2b-error {{no matching constructor for initialization}}
} catch (...) {
}
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -8837,6 +8837,10 @@
if (E->isTypeDependent())
return S.Context.DependentTy;
+ Expr *IDExpr = E;
+ if (auto *ImplCastExpr = dyn_cast<ImplicitCastExpr>(E))
+ IDExpr = ImplCastExpr->getSubExpr();
+
// C++11 [dcl.type.simple]p4:
// The type denoted by decltype(e) is defined as follows:
@@ -8847,7 +8851,7 @@
// Note that this does not pick up the implicit 'const' for a template
// parameter object. This rule makes no difference before C++20 so we apply
// it unconditionally.
- if (const auto *SNTTPE = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
+ if (const auto *SNTTPE = dyn_cast<SubstNonTypeTemplateParmExpr>(IDExpr))
return SNTTPE->getParameterType(S.Context);
// - if e is an unparenthesized id-expression or an unparenthesized class
@@ -8856,21 +8860,22 @@
// functions, the program is ill-formed;
//
// We apply the same rules for Objective-C ivar and property references.
- if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
+ if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(IDExpr)) {
const ValueDecl *VD = DRE->getDecl();
if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(VD))
return TPO->getType().getUnqualifiedType();
return VD->getType();
- } else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
+ } else if (const MemberExpr *ME = dyn_cast<MemberExpr>(IDExpr)) {
if (const ValueDecl *VD = ME->getMemberDecl())
if (isa<FieldDecl>(VD) || isa<VarDecl>(VD))
return VD->getType();
- } else if (const ObjCIvarRefExpr *IR = dyn_cast<ObjCIvarRefExpr>(E)) {
+ } else if (const ObjCIvarRefExpr *IR = dyn_cast<ObjCIvarRefExpr>(IDExpr)) {
return IR->getDecl()->getType();
- } else if (const ObjCPropertyRefExpr *PR = dyn_cast<ObjCPropertyRefExpr>(E)) {
+ } else if (const ObjCPropertyRefExpr *PR =
+ dyn_cast<ObjCPropertyRefExpr>(IDExpr)) {
if (PR->isExplicitProperty())
return PR->getExplicitProperty()->getType();
- } else if (auto *PE = dyn_cast<PredefinedExpr>(E)) {
+ } else if (auto *PE = dyn_cast<PredefinedExpr>(IDExpr)) {
return PE->getType();
}
@@ -8883,8 +8888,8 @@
// entity.
using namespace sema;
if (S.getCurLambda()) {
- if (isa<ParenExpr>(E)) {
- if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
+ if (isa<ParenExpr>(IDExpr)) {
+ if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(IDExpr->IgnoreParens())) {
if (VarDecl *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
QualType T = S.getCapturedDeclRefType(Var, DRE->getLocation());
if (!T.isNull())
Index: clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1052,10 +1052,19 @@
StartingScope, InstantiatingVarTemplate);
if (D->isNRVOVariable()) {
- QualType ReturnType = cast<FunctionDecl>(DC)->getReturnType();
- if (SemaRef.isCopyElisionCandidate(ReturnType, Var, Sema::CES_Strict))
- Var->setNRVOVariable(true);
+ QualType ReturnType;
+ if (auto *F = dyn_cast<FunctionDecl>(DC))
+ ReturnType = F->getReturnType();
+ else if (auto *F = dyn_cast<BlockDecl>(DC))
+ goto unimplemented; // FIXME: get the return type here somehow...
+ else
+ assert(false && "Unknown context type");
+
+ Sema::NRVOResult Res = SemaRef.getNRVOResult(Var);
+ SemaRef.getNRVOResultFnRetType(Res, ReturnType);
+ Var->setNRVOVariable(Res.isCopyElidable());
}
+unimplemented:
Var->setImplicit(D->isImplicit());
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -3026,99 +3026,134 @@
return new (Context) BreakStmt(BreakLoc);
}
-/// Determine whether the given expression is a candidate for
-/// copy elision in either a return statement or a throw expression.
-///
-/// \param ReturnType If we're determining the copy elision candidate for
-/// a return statement, this is the return type of the function. If we're
-/// determining the copy elision candidate for a throw expression, this will
-/// be a NULL type.
+static void downgradeNRVOResult(Sema::NRVOResult &Res, bool CanMove) {
+ Res.S = CanMove ? std::min(Res.S, Sema::NRVOResult::MoveEligible)
+ : Sema::NRVOResult::None;
+}
+
+/// Determine whether the given NRVO candidate variable is move-eligible or
+/// copy-elision eligible, without considering function return type.
///
-/// \param E The expression being returned from the function or block, or
-/// being thrown.
+/// \param VD The NRVO candidate variable.
///
-/// \param CESK Whether we allow function parameters or
-/// id-expressions that could be moved out of the function to be considered NRVO
-/// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to
-/// determine whether we should try to move as part of a return or throw (which
-/// does allow function parameters).
+/// \param ForceCXX20 Overrides detection of current language mode
+/// and uses the rules for C++20.
///
-/// \returns The NRVO candidate variable, if the return statement may use the
-/// NRVO, or NULL if there is no such candidate.
-VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E,
- CopyElisionSemanticsKind CESK) {
- // - in a return statement in a function [where] ...
- // ... the expression is the name of a non-volatile automatic object ...
- DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
- if (!DR || DR->refersToEnclosingVariableOrCapture())
- return nullptr;
- VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
+/// \returns An aggregate which contains the Candidate and isMoveEligible
+/// and isCopyElidable methods. If Candidate is non-null, it means
+/// isMoveEligible() would be true under the most permissive language standard.
+Sema::NRVOResult Sema::getNRVOResult(const VarDecl *VD, bool ForceCXX20) {
if (!VD)
- return nullptr;
+ return NRVOResult();
- if (isCopyElisionCandidate(ReturnType, VD, CESK))
- return VD;
- return nullptr;
-}
+ bool hasCXX11 = getLangOpts().CPlusPlus11 || ForceCXX20,
+ hasCXX20 = getLangOpts().CPlusPlus20 || ForceCXX20;
+ NRVOResult Res{VD, NRVOResult::MoveEligibleAndCopyElidable};
-bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
- CopyElisionSemanticsKind CESK) {
- QualType VDType = VD->getType();
- // - in a return statement in a function with ...
- // ... a class return type ...
- if (!ReturnType.isNull() && !ReturnType->isDependentType()) {
- if (!ReturnType->isRecordType())
- return false;
- // ... the same cv-unqualified type as the function return type ...
- // When considering moving this expression out, allow dissimilar types.
- if (!(CESK & CES_AllowDifferentTypes) && !VDType->isDependentType() &&
- !Context.hasSameUnqualifiedType(ReturnType, VDType))
- return false;
+ // (other than a function ... parameter)
+ if (VD->getKind() == Decl::ParmVar) {
+ downgradeNRVOResult(Res, hasCXX11);
+ } else if (VD->getKind() != Decl::Var) {
+ return NRVOResult();
}
- // ...object (other than a function or catch-clause parameter)...
- if (VD->getKind() != Decl::Var &&
- !((CESK & CES_AllowParameters) && VD->getKind() == Decl::ParmVar))
- return false;
- if (!(CESK & CES_AllowExceptionVariables) && VD->isExceptionVariable())
- return false;
+ // (other than ... a catch-clause parameter)
+ if (VD->isExceptionVariable())
+ downgradeNRVOResult(Res, hasCXX20);
// ...automatic...
- if (!VD->hasLocalStorage()) return false;
+ if (!VD->hasLocalStorage())
+ return NRVOResult();
// Return false if VD is a __block variable. We don't want to implicitly move
// out of a __block variable during a return because we cannot assume the
// variable will no longer be used.
if (VD->hasAttr<BlocksAttr>())
- return false;
+ return NRVOResult();
+ QualType VDType = VD->getType();
if (VDType->isObjectType()) {
// C++17 [class.copy.elision]p3:
// ...non-volatile automatic object...
if (VDType.isVolatileQualified())
- return false;
+ return NRVOResult();
} else if (VDType->isRValueReferenceType()) {
// C++20 [class.copy.elision]p3:
- // ...either a non-volatile object or an rvalue reference to a non-volatile object type...
- if (!(CESK & CES_AllowRValueReferenceType))
- return false;
+ // ...either a non-volatile object or an rvalue reference to a non-volatile
+ // object type...
QualType VDReferencedType = VDType.getNonReferenceType();
- if (VDReferencedType.isVolatileQualified() || !VDReferencedType->isObjectType())
- return false;
+ if (VDReferencedType.isVolatileQualified() ||
+ !VDReferencedType->isObjectType())
+ return NRVOResult();
+ downgradeNRVOResult(Res, hasCXX20);
} else {
- return false;
+ return NRVOResult();
}
- if (CESK & CES_AllowDifferentTypes)
- return true;
-
// Variables with higher required alignment than their type's ABI
// alignment cannot use NRVO.
if (!VDType->isDependentType() && VD->hasAttr<AlignedAttr>() &&
Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VDType))
- return false;
+ downgradeNRVOResult(Res, hasCXX11);
- return true;
+ return Res;
+}
+
+/// Determine whether the given expression might be move-eligible or
+/// copy-elidable in either a (co_)return statement or throw expression,
+/// without considering function return type, if applicable.
+///
+/// \param E The expression being returned from the function or block,
+/// being thrown, or being co_returned from a coroutine. This expression
+/// might be modified by the implementation.
+///
+/// \param ForceCXX2b Overrides detection of current language mode
+/// and uses the rules for C++2b.
+///
+/// \returns An aggregate which contains the Candidate and isMoveEligible
+/// and isCopyElidable methods. If Candidate is non-null, it means
+/// isMoveEligible() would be true under the most permissive language standard.
+Sema::NRVOResult Sema::getNRVOCandidate(Expr *&E, bool ForceCXX2b) {
+ if (!E)
+ return NRVOResult();
+ // - in a return statement in a function [where] ...
+ // ... the expression is the name of a non-volatile automatic object ...
+ DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E->IgnoreParens());
+ if (!DR || DR->refersToEnclosingVariableOrCapture())
+ return NRVOResult();
+ VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
+ NRVOResult Res = getNRVOResult(VD, /*ForceCXX20=*/ForceCXX2b);
+ if (Res.Candidate && E->getValueKind() != VK_XValue &&
+ (ForceCXX2b || getLangOpts().CPlusPlus2b)) {
+ E = ImplicitCastExpr::Create(Context, VD->getType().getNonReferenceType(),
+ CK_NoOp, E, nullptr, VK_XValue,
+ FPOptionsOverride());
+ }
+ return Res;
+}
+
+/// Updates given NRVOResult's move-eligible and
+/// copy-elidable statuses, considering the function return type criteria
+/// as applicable to return statements.
+///
+/// \param Res The NRVOResult object to update.
+///
+/// \param ReturnType This is the return type of the function.
+void Sema::getNRVOResultFnRetType(NRVOResult &Res, QualType ReturnType) {
+ if (!Res.Candidate || ReturnType->isDependentType())
+ return;
+ // - in a return statement in a function with ...
+ // ... a class return type ...
+ if (!ReturnType->isRecordType()) {
+ Res = NRVOResult();
+ return;
+ }
+ QualType VDType = Res.Candidate->getType();
+ // ... the same cv-unqualified type as the function return type ...
+ // When considering moving this expression out, allow dissimilar types.
+ if (!VDType->isDependentType() &&
+ !Context.hasSameUnqualifiedType(ReturnType, VDType))
+ downgradeNRVOResult(Res, getLangOpts().CPlusPlus11);
}
/// Try to perform the initialization of a potentially-movable value,
@@ -3229,61 +3264,42 @@
/// construction), then falls back to treating them as lvalues if that failed.
ExprResult Sema::PerformMoveOrCopyInitialization(
const InitializedEntity &Entity, const VarDecl *NRVOCandidate,
- QualType ResultType, Expr *Value, bool AllowNRVO) {
- ExprResult Res = ExprError();
- bool NeedSecondOverloadResolution = true;
-
- if (AllowNRVO) {
- CopyElisionSemanticsKind CESK = CES_Strict;
- if (getLangOpts().CPlusPlus20) {
- CESK = CES_ImplicitlyMovableCXX20;
- } else if (getLangOpts().CPlusPlus11) {
- CESK = CES_ImplicitlyMovableCXX11CXX14CXX17;
- }
-
- if (!NRVOCandidate) {
- NRVOCandidate = getCopyElisionCandidate(ResultType, Value, CESK);
- }
-
- if (NRVOCandidate) {
- NeedSecondOverloadResolution =
- TryMoveInitialization(*this, Entity, NRVOCandidate, ResultType, Value,
- !getLangOpts().CPlusPlus20, false, Res);
+ QualType ResultType, Expr *Value, bool isMoveEligible) {
+
+ if (NRVOCandidate && !getLangOpts().CPlusPlus2b) {
+ if (isMoveEligible) {
+ ExprResult Res;
+ if (!TryMoveInitialization(*this, Entity, NRVOCandidate, ResultType,
+ Value, !getLangOpts().CPlusPlus20, false, Res))
+ return Res;
}
-
- if (!getLangOpts().CPlusPlus20 && NeedSecondOverloadResolution &&
- !getDiagnostics().isIgnored(diag::warn_return_std_move,
+ if (!getDiagnostics().isIgnored(diag::warn_return_std_move,
Value->getExprLoc())) {
- const VarDecl *FakeNRVOCandidate = getCopyElisionCandidate(
- QualType(), Value, CES_ImplicitlyMovableCXX20);
- if (FakeNRVOCandidate) {
- QualType QT = FakeNRVOCandidate->getType();
- if (QT->isLValueReferenceType()) {
- // Adding 'std::move' around an lvalue reference variable's name is
- // dangerous. Don't suggest it.
- } else if (QT.getNonReferenceType()
- .getUnqualifiedType()
- .isTriviallyCopyableType(Context)) {
- // Adding 'std::move' around a trivially copyable variable is probably
- // pointless. Don't suggest it.
- } else {
- ExprResult FakeRes = ExprError();
- Expr *FakeValue = Value;
- TryMoveInitialization(*this, Entity, FakeNRVOCandidate, ResultType,
- FakeValue, false, true, FakeRes);
- if (!FakeRes.isInvalid()) {
- bool IsThrow =
- (Entity.getKind() == InitializedEntity::EK_Exception);
- SmallString<32> Str;
- Str += "std::move(";
- Str += FakeNRVOCandidate->getDeclName().getAsString();
- Str += ")";
- Diag(Value->getExprLoc(), diag::warn_return_std_move)
- << Value->getSourceRange()
- << FakeNRVOCandidate->getDeclName() << IsThrow;
- Diag(Value->getExprLoc(), diag::note_add_std_move)
- << FixItHint::CreateReplacement(Value->getSourceRange(), Str);
- }
+ QualType QT = NRVOCandidate->getType();
+ if (QT->isLValueReferenceType()) {
+ // Adding 'std::move' around an lvalue reference variable's name is
+ // dangerous. Don't suggest it.
+ } else if (QT.getNonReferenceType()
+ .getUnqualifiedType()
+ .isTriviallyCopyableType(Context)) {
+ // Adding 'std::move' around a trivially copyable variable is probably
+ // pointless. Don't suggest it.
+ } else {
+ ExprResult FakeRes = ExprError();
+ Expr *FakeValue = Value;
+ TryMoveInitialization(*this, Entity, NRVOCandidate, ResultType,
+ FakeValue, false, true, FakeRes);
+ if (!FakeRes.isInvalid()) {
+ bool IsThrow = (Entity.getKind() == InitializedEntity::EK_Exception);
+ SmallString<32> Str;
+ Str += "std::move(";
+ Str += NRVOCandidate->getDeclName().getAsString();
+ Str += ")";
+ Diag(Value->getExprLoc(), diag::warn_return_std_move)
+ << Value->getSourceRange() << NRVOCandidate->getDeclName()
+ << IsThrow;
+ Diag(Value->getExprLoc(), diag::note_add_std_move)
+ << FixItHint::CreateReplacement(Value->getSourceRange(), Str);
}
}
}
@@ -3292,10 +3308,7 @@
// Either we didn't meet the criteria for treating an lvalue as an rvalue,
// above, or overload resolution failed. Either way, we need to try
// (again) now with the return value expression as written.
- if (NeedSecondOverloadResolution)
- Res = PerformCopyInitialization(Entity, SourceLocation(), Value);
-
- return Res;
+ return PerformCopyInitialization(Entity, SourceLocation(), Value);
}
/// Determine whether the declared return type of the specified function
@@ -3309,8 +3322,8 @@
/// ActOnCapScopeReturnStmt - Utility routine to type-check return statements
/// for capturing scopes.
///
-StmtResult
-Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
+StmtResult Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,
+ Expr *RetValExp, NRVOResult &NRVORes) {
// If this is the first return we've seen, infer the return type.
// [expr.prim.lambda]p4 in C++11; block literals follow the same rules.
CapturingScopeInfo *CurCap = cast<CapturingScopeInfo>(getCurFunction());
@@ -3390,6 +3403,7 @@
CurCap->ReturnType = FnRetType;
}
assert(!FnRetType.isNull());
+ getNRVOResultFnRetType(NRVORes, FnRetType);
if (auto *CurBlock = dyn_cast<BlockScopeInfo>(CurCap)) {
if (CurBlock->FunctionType->castAs<FunctionType>()->getNoReturnAttr()) {
@@ -3412,7 +3426,6 @@
// Otherwise, verify that this result type matches the previous one. We are
// pickier with blocks than for normal functions because we don't have GCC
// compatibility to worry about here.
- const VarDecl *NRVOCandidate = nullptr;
if (FnRetType->isDependentType()) {
// Delay processing for now. TODO: there are lots of dependent
// types we can conclusively prove aren't void.
@@ -3440,20 +3453,17 @@
// In C++ the return statement is handled via a copy initialization.
// the C version of which boils down to CheckSingleAssignmentConstraints.
- NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
- InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
- FnRetType,
- NRVOCandidate != nullptr);
- ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
- FnRetType, RetValExp);
+ InitializedEntity Entity = InitializedEntity::InitializeResult(
+ ReturnLoc, FnRetType, NRVORes.isCopyElidable());
+ ExprResult Res =
+ PerformMoveOrCopyInitialization(Entity, NRVORes.Candidate, FnRetType,
+ RetValExp, NRVORes.isMoveEligible());
if (Res.isInvalid()) {
// FIXME: Cleanup temporaries here, anyway?
return StmtError();
}
RetValExp = Res.get();
CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc);
- } else {
- NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
}
if (RetValExp) {
@@ -3463,13 +3473,14 @@
return StmtError();
RetValExp = ER.get();
}
- auto *Result =
- ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
+ auto *Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp,
+ NRVORes.isCopyElidable() ? NRVORes.Candidate
+ : nullptr);
// If we need to check for the named return value optimization,
// or if we need to infer the return type,
// save the return statement in our scope for later processing.
- if (CurCap->HasImplicitReturnType || NRVOCandidate)
+ if (CurCap->HasImplicitReturnType || NRVORes.isCopyElidable())
FunctionScopes.back()->Returns.push_back(Result);
if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
@@ -3662,8 +3673,10 @@
if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp))
return StmtError();
+ NRVOResult NRVORes = getNRVOCandidate(RetValExp);
+
if (isa<CapturingScopeInfo>(getCurFunction()))
- return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp);
+ return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp, NRVORes);
QualType FnRetType;
QualType RelatedRetType;
@@ -3735,6 +3748,7 @@
}
}
}
+ getNRVOResultFnRetType(NRVORes, FnRetType);
bool HasDependentReturnType = FnRetType->isDependentType();
@@ -3841,8 +3855,6 @@
/* NRVOCandidate=*/nullptr);
} else {
assert(RetValExp || HasDependentReturnType);
- const VarDecl *NRVOCandidate = nullptr;
-
QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType;
// C99 6.8.6.4p3(136): The return statement is not an assignment. The
@@ -3851,15 +3863,13 @@
// In C++ the return statement is handled via a copy initialization,
// the C version of which boils down to CheckSingleAssignmentConstraints.
- if (RetValExp)
- NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict);
if (!HasDependentReturnType && !RetValExp->isTypeDependent()) {
// we have a non-void function with an expression, continue checking
- InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc,
- RetType,
- NRVOCandidate != nullptr);
- ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate,
- RetType, RetValExp);
+ InitializedEntity Entity = InitializedEntity::InitializeResult(
+ ReturnLoc, RetType, NRVORes.isCopyElidable());
+ ExprResult Res =
+ PerformMoveOrCopyInitialization(Entity, NRVORes.Candidate, RetType,
+ RetValExp, NRVORes.isMoveEligible());
if (Res.isInvalid()) {
// FIXME: Clean up temporaries here anyway?
return StmtError();
@@ -3892,7 +3902,9 @@
return StmtError();
RetValExp = ER.get();
}
- Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate);
+ Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp,
+ NRVORes.isCopyElidable() ? NRVORes.Candidate
+ : nullptr);
}
// If we need to check for the named return value optimization, save the
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -851,6 +851,9 @@
Diag(OpLoc, diag::err_omp_simd_region_cannot_use_stmt) << "throw";
if (Ex && !Ex->isTypeDependent()) {
+ NRVOResult NRVORes =
+ IsThrownVarInScope ? getNRVOCandidate(Ex) : NRVOResult();
+
QualType ExceptionObjectTy = Context.getExceptionObjectType(Ex->getType());
if (CheckCXXThrowOperand(OpLoc, ExceptionObjectTy, Ex))
return ExprError();
@@ -870,15 +873,12 @@
// operation from the operand to the exception object (15.1) can be
// omitted by constructing the automatic object directly into the
// exception object
- const VarDecl *NRVOVariable = nullptr;
- if (IsThrownVarInScope)
- NRVOVariable = getCopyElisionCandidate(QualType(), Ex, CES_Strict);
InitializedEntity Entity = InitializedEntity::InitializeException(
OpLoc, ExceptionObjectTy,
- /*NRVO=*/NRVOVariable != nullptr);
+ /*NRVO=*/NRVORes.isCopyElidable());
ExprResult Res = PerformMoveOrCopyInitialization(
- Entity, NRVOVariable, QualType(), Ex, IsThrownVarInScope);
+ Entity, NRVORes.Candidate, QualType(), Ex, NRVORes.isMoveEligible());
if (Res.isInvalid())
return ExprError();
Ex = Res.get();
Index: clang/lib/Sema/SemaCoroutine.cpp
===================================================================
--- clang/lib/Sema/SemaCoroutine.cpp
+++ clang/lib/Sema/SemaCoroutine.cpp
@@ -994,26 +994,10 @@
E = R.get();
}
- // Move the return value if we can
- if (E) {
- const VarDecl *NRVOCandidate = this->getCopyElisionCandidate(
- E->getType(), E, CES_ImplicitlyMovableCXX20);
- if (NRVOCandidate) {
- InitializedEntity Entity =
- InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate);
- ExprResult MoveResult = this->PerformMoveOrCopyInitialization(
- Entity, NRVOCandidate, E->getType(), E);
- if (MoveResult.get())
- E = MoveResult.get();
- }
- }
-
- // FIXME: If the operand is a reference to a variable that's about to go out
- // of scope, we should treat the operand as an xvalue for this overload
- // resolution.
VarDecl *Promise = FSI->CoroutinePromise;
ExprResult PC;
if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
+ getNRVOCandidate(E, /*ForceCXX2b=*/true);
PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
} else {
E = MakeFullDiscardedValueExpr(E).get();
@@ -1570,7 +1554,7 @@
// Trigger a nice error message.
InitializedEntity Entity =
InitializedEntity::InitializeResult(Loc, FnRetType, false);
- S.PerformMoveOrCopyInitialization(Entity, nullptr, FnRetType, ReturnValue);
+ S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
noteMemberDeclaredHere(S, ReturnValue, Fn);
return false;
}
@@ -1586,8 +1570,8 @@
return false;
InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
- ExprResult Res = S.PerformMoveOrCopyInitialization(Entity, nullptr, GroType,
- this->ReturnValue);
+ ExprResult Res =
+ S.PerformCopyInitialization(Entity, SourceLocation(), ReturnValue);
if (Res.isInvalid())
return false;
Index: clang/lib/Sema/Sema.cpp
===================================================================
--- clang/lib/Sema/Sema.cpp
+++ clang/lib/Sema/Sema.cpp
@@ -1952,9 +1952,10 @@
SourceLocation Loc = VD->getLocation();
Expr *VarRef =
new (S.Context) DeclRefExpr(S.Context, VD, false, T, VK_LValue, Loc);
- ExprResult Result = S.PerformMoveOrCopyInitialization(
- InitializedEntity::InitializeBlock(Loc, T, false), VD, VD->getType(),
- VarRef, /*AllowNRVO=*/true);
+ ExprResult Result = S.PerformCopyInitialization(
+ InitializedEntity::InitializeBlock(Loc, T, false), SourceLocation(),
+ VarRef);
+
if (!Result.isInvalid()) {
Result = S.MaybeCreateExprWithCleanups(Result);
Expr *Init = Result.getAs<Expr>();
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -3436,9 +3436,8 @@
ExprResult PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
const VarDecl *NRVOCandidate,
- QualType ResultType,
- Expr *Value,
- bool AllowNRVO = true);
+ QualType ResultType, Expr *Value,
+ bool isMoveEligible);
bool CanPerformAggregateInitializationForOverloadResolution(
const InitializedEntity &Entity, InitListExpr *From);
@@ -4736,28 +4735,24 @@
SourceLocation Loc,
unsigned NumParams);
- enum CopyElisionSemanticsKind {
- CES_Strict = 0,
- CES_AllowParameters = 1,
- CES_AllowDifferentTypes = 2,
- CES_AllowExceptionVariables = 4,
- CES_AllowRValueReferenceType = 8,
- CES_ImplicitlyMovableCXX11CXX14CXX17 =
- (CES_AllowParameters | CES_AllowDifferentTypes),
- CES_ImplicitlyMovableCXX20 =
- (CES_AllowParameters | CES_AllowDifferentTypes |
- CES_AllowExceptionVariables | CES_AllowRValueReferenceType),
- };
+ struct NRVOResult {
+ const VarDecl *Candidate;
+
+ enum Status { None, MoveEligible, MoveEligibleAndCopyElidable };
+ Status S;
- VarDecl *getCopyElisionCandidate(QualType ReturnType, Expr *E,
- CopyElisionSemanticsKind CESK);
- bool isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD,
- CopyElisionSemanticsKind CESK);
+ bool isMoveEligible() { return S >= MoveEligible; };
+ bool isCopyElidable() { return S == MoveEligibleAndCopyElidable; }
+ };
+ NRVOResult getNRVOCandidate(Expr *&E, bool ForceCXX2b = false);
+ NRVOResult getNRVOResult(const VarDecl *VD, bool ForceCXX20 = false);
+ void getNRVOResultFnRetType(NRVOResult &Res, QualType ReturnType);
StmtResult ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
Scope *CurScope);
StmtResult BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp);
- StmtResult ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp);
+ StmtResult ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
+ NRVOResult &NRVORes);
StmtResult ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
bool IsVolatile, unsigned NumOutputs,
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