Author: rsmith
Date: Fri Jul 6 22:58:48 2018
New Revision: 336480
URL: http://llvm.org/viewvc/llvm-project?rev=336480&view=rev
Log:
P0806R2 Implicit capture of this with a capture-default of [=] is
deprecated.
Add a -Wdeprecated warning for this in C++2a onwards. (In C++17 and
before, there isn't a reasonable alternative because [=,this] is
ill-formed.)
Modified:
cfe/trunk/include/clang/Basic/DiagnosticGroups.td
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaLambda.cpp
cfe/trunk/test/SemaCXX/cxx2a-lambda-equals-this.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=336480&r1=336479&r2=336480&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Fri Jul 6 22:58:48 2018
@@ -120,6 +120,7 @@ def DeprecatedDynamicExceptionSpec
def DeprecatedImplementations :DiagGroup<"deprecated-implementations">;
def DeprecatedIncrementBool : DiagGroup<"deprecated-increment-bool">;
def DeprecatedRegister : DiagGroup<"deprecated-register">;
+def DeprecatedThisCapture : DiagGroup<"deprecated-this-capture">;
def DeprecatedWritableStr : DiagGroup<"deprecated-writable-strings",
[CXX11CompatDeprecatedWritableStr]>;
// FIXME: Why is DeprecatedImplementations not in this group?
@@ -128,6 +129,7 @@ def Deprecated : DiagGroup<"deprecated",
DeprecatedDynamicExceptionSpec,
DeprecatedIncrementBool,
DeprecatedRegister,
+ DeprecatedThisCapture,
DeprecatedWritableStr]>,
DiagCategory<"Deprecations">;
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=336480&r1=336479&r2=336480&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Jul 6 22:58:48
2018
@@ -6545,6 +6545,11 @@ let CategoryName = "Lambda Issue" in {
def ext_equals_this_lambda_capture_cxx2a : ExtWarn<
"explicit capture of 'this' with a capture default of '=' "
"is a C++2a extension">, InGroup<CXX2a>;
+ def warn_deprecated_this_capture : Warning<
+ "implicit capture of 'this' with a capture default of '=' is deprecated">,
+ InGroup<DeprecatedThisCapture>, DefaultIgnore;
+ def note_deprecated_this_capture : Note<
+ "add an explicit capture of 'this' to capture '*this' by reference">;
}
def err_return_in_captured_stmt : Error<
Modified: cfe/trunk/lib/Sema/SemaLambda.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLambda.cpp?rev=336480&r1=336479&r2=336480&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaLambda.cpp (original)
+++ cfe/trunk/lib/Sema/SemaLambda.cpp Fri Jul 6 22:58:48 2018
@@ -1548,6 +1548,17 @@ ExprResult Sema::BuildLambdaExpr(SourceL
// Handle 'this' capture.
if (From.isThisCapture()) {
+ // Capturing 'this' implicitly with a default of '[=]' is deprecated,
+ // because it results in a reference capture. Don't warn prior to
+ // C++2a; there's nothing that can be done about it before then.
+ if (getLangOpts().CPlusPlus2a && IsImplicit &&
+ CaptureDefault == LCD_ByCopy) {
+ Diag(From.getLocation(), diag::warn_deprecated_this_capture);
+ Diag(CaptureDefaultLoc, diag::note_deprecated_this_capture)
+ << FixItHint::CreateInsertion(
+ getLocForEndOfToken(CaptureDefaultLoc), ", this");
+ }
+
Captures.push_back(
LambdaCapture(From.getLocation(), IsImplicit,
From.isCopyCapture() ? LCK_StarThis : LCK_This));
Modified: cfe/trunk/test/SemaCXX/cxx2a-lambda-equals-this.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx2a-lambda-equals-this.cpp?rev=336480&r1=336479&r2=336480&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/cxx2a-lambda-equals-this.cpp (original)
+++ cfe/trunk/test/SemaCXX/cxx2a-lambda-equals-this.cpp Fri Jul 6 22:58:48 2018
@@ -1,5 +1,4 @@
-// RUN: %clang_cc1 -std=c++2a -verify %s
-// expected-no-diagnostics
+// RUN: %clang_cc1 -std=c++2a -verify %s -Wdeprecated
// This test does two things.
// Deleting the copy constructor ensures that an [=, this] capture doesn't
copy the object.
@@ -13,3 +12,12 @@ class A {
L();
}
};
+
+struct B {
+ int i;
+ void f() {
+ (void) [=] { // expected-note {{add an explicit capture of 'this'}}
+ return i; // expected-warning {{implicit capture of 'this' with a
capture default of '=' is deprecated}}
+ };
+ }
+};
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