OK.
On Wed, Aug 28, 2019 at 7:56 PM Marek Polacek <pola...@redhat.com> wrote:
>
> On Wed, Aug 28, 2019 at 04:08:39PM -0400, Jason Merrill wrote:
> > On 8/26/19 1:46 PM, Marek Polacek wrote:
> > > +Wvolatile
> > > +C++ ObjC++ Var(warn_volatile) Warning
> > > +Warn about certain uses of volatile qualifier.
> >
> > Maybe "deprecated uses"?
>
> Ok, changed.
>
> > > --- gcc/cp/expr.c
> > > +++ gcc/cp/expr.c
> > > @@ -207,6 +207,27 @@ mark_use (tree expr, bool rvalue_p, bool read_p,
> > > recurse_op[0] = true;
> > > break;
> > > + case MODIFY_EXPR:
> > > + {
> > > + tree lhs = TREE_OPERAND (expr, 0);
> > > + /* [expr.ass] "A simple assignment whose left operand is of
> > > + a volatile-qualified type is deprecated unless the assignment
> > > + is either a discarded-value expression or appears in an
> > > + unevaluated context." */
> > > + if (read_p
> > > + && (TREE_THIS_VOLATILE (lhs)
> > > + || CP_TYPE_VOLATILE_P (TREE_TYPE (lhs)))
> > > + && !TREE_THIS_VOLATILE (expr))
> > > + {
> > > + warning_at (location_of (expr), OPT_Wvolatile,
> > > + "assignment with %<volatile%>-qualified left "
> > > + "operand is deprecated");
> >
> > This should be more specific; the assignment itself isn't deprecated, but
> > rather using the assignment as an lvalue or rvalue.
>
> This now reads "using value of simple assignment with volatile-qualified left
> operand is deprecated".
>
> > > + /* An expression of the form E1 op= E2. [expr.ass] says:
> > > + "Such expressions are deprecated if E1 has volatile-qualified
> > > + type." We warn here rather than in cp_genericize_r because
> > > + for compound assignments we are supposed to warn even if the
> > > + assignment is a discarded-value expression. */
> > > + if (TREE_THIS_VOLATILE (lhs) || CP_TYPE_VOLATILE_P (lhstype))
> > > + warning_at (loc, OPT_Wvolatile,
> > > + "assignment with %<volatile%>-qualified left operand "
> > > + "is deprecated");
> >
> > And this should say "compound assignment ..."
>
> Fixed.
>
> > > +@item -Wvolatile @r{(C++ and Objective-C++ only)}
> > > +@opindex Wvolatile
> > > +@opindex Wno-volatile
> > > +Warn about certain uses of volatile qualifier. This includes postfix
> > > +@code{++} and @code{--} expressions, prefix @code{++} and @code{--}
> > > +expressions, certain assignments where the left operand is a
> > > +volatile-qualified non-class type
> >
> > This should also be more specific.
>
> Improved (hopefully).
>
> > > +
> > > + // Unevaluated operand.
> > > + decltype(vi = 42) x = vi;
> >
> > I guess we should also test that there's no warning for
> >
> > decltype(i = vi = 42)
> >
> > since this is also an unevaluated context. It's a bit odd the proposal uses
> > "unevaluated context" rather than "unevaluated operand".
>
> Yes we should, and *of course* it was a case where my patch emitted a bogus
> warning. But it was trivial to fix by checking cp_unevaluated_operand.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2019-08-28 Marek Polacek <pola...@redhat.com>
>
> Implement P1152R4: Deprecating some uses of volatile.
> PR c++/91361
> * c-opts.c (c_common_post_options): Enable -Wvolatile by
> default for C++2a, unless -Wno-deprecated.
> * c.opt (Wvolatile): New warning.
>
> * cp-gimplify.c (cp_fold): Set TREE_THIS_VOLATILE.
> * decl.c (grokdeclarator): Warn about a volatile-qualified structured
> binding and return type.
> (grokparms): Warn about a volatile-qualified function parameter.
> * expr.c (mark_use) <case MODIFY_EXPR>: Emit a -Wvolatile warning.
> * typeck.c (cp_build_unary_op): Emit a -Wvolatile warning for pre and
> post ++/-- on a volatile operand.
> (genericize_compound_lvalue): Use a better location. Don't lose
> TREE_THIS_VOLATILE.
> (cp_build_modify_expr): Emit a -Wvolatile warning for a compound
> assignment whose LHS is volatile-qualified. Build the assignment with
> a more precise location.
>
> * doc/invoke.texi: Document -Wvolatile.
>
> * c-c++-common/Wbool-operation-1.c: Use -Wno-volatile in C++.
> * c-c++-common/gomp/atomic-1.c: Likewise.
> * c-c++-common/gomp/atomic-9.c: Likewise.
> * c-c++-common/gomp/depend-iterator-1.c: Likewise.
> * c-c++-common/gomp/loop-1.c: Adjust warning location for C++.
> * c-c++-common/gomp/order-3.c: Likewise.
> * c-c++-common/pr69733.c: Use -Wno-volatile in C++.
> * c-c++-common/spec-barrier-2.c: Likewise.
> * c-c++-common/tm/pr54893.c: Likewise.
> * g++.dg/cpp0x/pr65327.C: Add dg-warning.
> * g++.dg/cpp0x/rv-conv2.C: Likewise.
> * g++.dg/cpp0x/rv1n.C: Likewise.
> * g++.dg/cpp0x/rv1p.C: Likewise.
> * g++.dg/cpp0x/rv2n.C: Likewise.
> * g++.dg/cpp0x/rv2p.C: Likewise.
> * g++.dg/cpp0x/rv3n.C: Likewise.
> * g++.dg/cpp0x/rv3p.C: Likewise.
> * g++.dg/cpp0x/rv4n.C: Likewise.
> * g++.dg/cpp0x/rv4p.C: Likewise.
> * g++.dg/cpp0x/rv5n.C: Likewise.
> * g++.dg/cpp0x/rv5p.C: Likewise.
> * g++.dg/cpp0x/rv6n.C: Likewise.
> * g++.dg/cpp0x/rv6p.C: Likewise.
> * g++.dg/cpp0x/rv7n.C: Likewise.
> * g++.dg/cpp0x/rv7p.C: Likewise.
> * g++.dg/cpp0x/rv8p.C: Likewise.
> * g++.dg/cpp0x/trailing14.C: Use -Wno-volatile.
> * g++.dg/cpp1y/new1.C: Add dg-warning.
> * g++.dg/cpp2a/volatile1.C: New test.
> * g++.dg/cpp2a/volatile2.C: New test.
> * g++.dg/cpp2a/volatile3.C: New test.
> * g++.dg/cpp2a/volatile4.C: New test.
> * g++.dg/expr/bool3.C: Add dg-warning.
> * g++.dg/expr/bool4.C: Likewise.
> * g++.dg/expr/cond9.C: Likewise.
> * g++.dg/ext/vector25.C: Likewise.
> * g++.dg/gomp/depend-iterator-1.C: Use -Wno-volatile.
> * g++.dg/inherit/covariant21.C: Add dg-warning.
> * g++.dg/init/ref18.C: Likewise.
> * g++.dg/ipa/pr63838.C: Likewise.
> * g++.dg/overload/rvalue2.C: Likewise.
> * g++.dg/parse/semicolon4.C: Likewise.
> * g++.dg/warn/Wreturn-type-4.C: Likewise.
> * g++.dg/warn/pr36069.C: Likewise.
> * g++.old-deja/g++.mike/p9506.C: Likewise.
> * g++.old-deja/g++.other/volatile1.C: Likewise.
>
> diff --git gcc/c-family/c-opts.c gcc/c-family/c-opts.c
> index da783e4990c..fa8cd0ccb09 100644
> --- gcc/c-family/c-opts.c
> +++ gcc/c-family/c-opts.c
> @@ -919,6 +919,10 @@ c_common_post_options (const char **pfilename)
> if (!global_options_set.x_warn_comma_subscript)
> warn_comma_subscript = (cxx_dialect >= cxx2a && warn_deprecated);
>
> + /* -Wvolatile is enabled by default in C++20. */
> + if (!global_options_set.x_warn_volatile)
> + warn_volatile = (cxx_dialect >= cxx2a && warn_deprecated);
> +
> /* Declone C++ 'structors if -Os. */
> if (flag_declone_ctor_dtor == -1)
> flag_declone_ctor_dtor = optimize_size;
> diff --git gcc/c-family/c.opt gcc/c-family/c.opt
> index 4c468d0f6c2..f8a1a1dbdad 100644
> --- gcc/c-family/c.opt
> +++ gcc/c-family/c.opt
> @@ -1228,6 +1228,10 @@ Wno-vla-larger-than
> C ObjC C++ LTO ObjC++ Alias(Wvla-larger-than=,18446744073709551615EiB,none)
> Warning
> -Wno-vla-larger-than Disable Wvla-larger-than= warning. Equivalent to
> Wvla-larger-than=<SIZE_MAX> or larger.
>
> +Wvolatile
> +C++ ObjC++ Var(warn_volatile) Warning
> +Warn about deprecated uses of volatile qualifier.
> +
> Wvolatile-register-var
> C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning LangEnabledBy(C
> ObjC C++ ObjC++,Wall)
> Warn when a register variable is declared volatile.
> diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
> index 065dcb7ba06..49fa47ac3af 100644
> --- gcc/cp/cp-gimplify.c
> +++ gcc/cp/cp-gimplify.c
> @@ -2507,6 +2507,9 @@ cp_fold (tree x)
> else
> x = org_x;
> }
> + if (code == MODIFY_EXPR && TREE_CODE (x) == MODIFY_EXPR)
> + TREE_THIS_VOLATILE (x) = TREE_THIS_VOLATILE (org_x);
> +
> break;
>
> case VEC_COND_EXPR:
> diff --git gcc/cp/decl.c gcc/cp/decl.c
> index c5cc22a8d6d..2aef330455f 100644
> --- gcc/cp/decl.c
> +++ gcc/cp/decl.c
> @@ -11233,6 +11233,10 @@ grokdeclarator (const cp_declarator *declarator,
> if (concept_p)
> error_at (declspecs->locations[ds_concept],
> "structured binding declaration cannot be %qs", "concept");
> + /* [dcl.struct.bind] "A cv that includes volatile is deprecated." */
> + if (type_quals & TYPE_QUAL_VOLATILE)
> + warning_at (declspecs->locations[ds_volatile], OPT_Wvolatile,
> + "%<volatile%>-qualified structured binding is
> deprecated");
> switch (storage_class)
> {
> case sc_none:
> @@ -11623,6 +11627,13 @@ grokdeclarator (const cp_declarator *declarator,
> if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type))
> warning_at (typespec_loc, OPT_Wignored_qualifiers, "type "
> "qualifiers ignored on function return type");
> + /* [dcl.fct] "A volatile-qualified return type is
> + deprecated." */
> + if (type_quals & TYPE_QUAL_VOLATILE)
> + warning_at (typespec_loc, OPT_Wvolatile,
> + "%<volatile%>-qualified return type is "
> + "deprecated");
> +
> /* We now know that the TYPE_QUALS don't apply to the
> decl, but to its return type. */
> type_quals = TYPE_UNQUALIFIED;
> @@ -13378,6 +13389,13 @@ grokparms (tree parmlist, tree *parms)
> cp_warn_deprecated_use (deptype);
> }
>
> + /* [dcl.fct] "A parameter with volatile-qualified type is
> + deprecated." */
> + if (CP_TYPE_VOLATILE_P (type))
> + warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wvolatile,
> + "%<volatile%>-qualified parameter is "
> + "deprecated");
> +
> /* Top-level qualifiers on the parameters are
> ignored for function types. */
> type = cp_build_qualified_type (type, 0);
> diff --git gcc/cp/expr.c gcc/cp/expr.c
> index 9160043ed11..212a7f93c5a 100644
> --- gcc/cp/expr.c
> +++ gcc/cp/expr.c
> @@ -207,6 +207,28 @@ mark_use (tree expr, bool rvalue_p, bool read_p,
> recurse_op[0] = true;
> break;
>
> + case MODIFY_EXPR:
> + {
> + tree lhs = TREE_OPERAND (expr, 0);
> + /* [expr.ass] "A simple assignment whose left operand is of
> + a volatile-qualified type is deprecated unless the assignment
> + is either a discarded-value expression or appears in an
> + unevaluated context." */
> + if (read_p
> + && !cp_unevaluated_operand
> + && (TREE_THIS_VOLATILE (lhs)
> + || CP_TYPE_VOLATILE_P (TREE_TYPE (lhs)))
> + && !TREE_THIS_VOLATILE (expr))
> + {
> + warning_at (location_of (expr), OPT_Wvolatile,
> + "using value of simple assignment with
> %<volatile%>-"
> + "qualified left operand is deprecated");
> + /* Make sure not to warn about this assignment again. */
> + TREE_THIS_VOLATILE (expr) = true;
> + }
> + break;
> + }
> +
> default:
> break;
> }
> diff --git gcc/cp/typeck.c gcc/cp/typeck.c
> index c09bb309142..d4f2d98143b 100644
> --- gcc/cp/typeck.c
> +++ gcc/cp/typeck.c
> @@ -6459,6 +6459,17 @@ cp_build_unary_op (enum tree_code code, tree xarg,
> bool noconvert,
> complain))
> return error_mark_node;
>
> + /* [depr.volatile.type] "Postfix ++ and -- expressions and
> + prefix ++ and -- expressions of volatile-qualified arithmetic
> + and pointer types are deprecated." */
> + if (TREE_THIS_VOLATILE (arg) || CP_TYPE_VOLATILE_P (TREE_TYPE (arg)))
> + warning_at (location, OPT_Wvolatile,
> + "%qs expression of %<volatile%>-qualified type is "
> + "deprecated",
> + ((code == PREINCREMENT_EXPR
> + || code == POSTINCREMENT_EXPR)
> + ? "++" : "--"));
> +
> /* Forbid using -- or ++ in C++17 on `bool'. */
> if (TREE_CODE (declared_type) == BOOLEAN_TYPE)
> {
> @@ -8278,6 +8289,15 @@ cp_build_modify_expr (location_t loc, tree lhs, enum
> tree_code modifycode,
> && MAYBE_CLASS_TYPE_P (TREE_TYPE (lhstype)))
> || MAYBE_CLASS_TYPE_P (lhstype)));
>
> + /* An expression of the form E1 op= E2. [expr.ass] says:
> + "Such expressions are deprecated if E1 has volatile-qualified
> + type." We warn here rather than in cp_genericize_r because
> + for compound assignments we are supposed to warn even if the
> + assignment is a discarded-value expression. */
> + if (TREE_THIS_VOLATILE (lhs) || CP_TYPE_VOLATILE_P (lhstype))
> + warning_at (loc, OPT_Wvolatile,
> + "compound assignment with %<volatile%>-qualified left
> "
> + "operand is deprecated");
> /* Preevaluate the RHS to make sure its evaluation is complete
> before the lvalue-to-rvalue conversion of the LHS:
>
> @@ -8450,8 +8470,8 @@ cp_build_modify_expr (location_t loc, tree lhs, enum
> tree_code modifycode,
> goto ret;
> }
>
> - result = build2 (modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
> - lhstype, lhs, newrhs);
> + result = build2_loc (loc, modifycode == NOP_EXPR ? MODIFY_EXPR : INIT_EXPR,
> + lhstype, lhs, newrhs);
>
> TREE_SIDE_EFFECTS (result) = 1;
> if (!plain_assign)
> diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
> index 1391a562c35..aa9886ee09f 100644
> --- gcc/doc/invoke.texi
> +++ gcc/doc/invoke.texi
> @@ -243,7 +243,7 @@ in the following sections.
> -Wno-non-template-friend -Wold-style-cast @gol
> -Woverloaded-virtual -Wno-pmf-conversions @gol
> -Wno-class-conversion -Wno-terminate @gol
> --Wsign-promo -Wvirtual-inheritance}
> +-Wsign-promo -Wvirtual-inheritance -Wvolatile}
>
> @item Objective-C and Objective-C++ Language Options
> @xref{Objective-C and Objective-C++ Dialect Options,,Options Controlling
> @@ -3516,6 +3516,19 @@ result in a call to @code{terminate}.
> Disable the warning about the case when a conversion function converts an
> object to the same type, to a base class of that type, or to void; such
> a conversion function will never be called.
> +
> +@item -Wvolatile @r{(C++ and Objective-C++ only)}
> +@opindex Wvolatile
> +@opindex Wno-volatile
> +Warn about deprecated uses of the volatile qualifier. This includes postfix
> +and prefix @code{++} and @code{--} expressions of volatile-qualified types,
> +using simple assignments where the left operand is a volatile-qualified
> +non-class type for their value, compound assignments where the left operand
> +is a volatile-qualified non-class type, volatile-qualified function return
> +type, volatile-qualified parameter type, and structured bindings of a
> +volatile-qualified type. This usage was deprecated in C++20.
> +
> +Enabled by default with @option{-std=c++2a}.
> @end table
>
> @node Objective-C and Objective-C++ Dialect Options
> diff --git gcc/testsuite/c-c++-common/Wbool-operation-1.c
> gcc/testsuite/c-c++-common/Wbool-operation-1.c
> index 04891878155..ce87705692a 100644
> --- gcc/testsuite/c-c++-common/Wbool-operation-1.c
> +++ gcc/testsuite/c-c++-common/Wbool-operation-1.c
> @@ -1,6 +1,7 @@
> /* PR c/77490 */
> /* { dg-do compile } */
> /* { dg-options "-Wall -Wno-psabi" } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
>
> #ifndef __cplusplus
> # define bool _Bool
> diff --git gcc/testsuite/c-c++-common/gomp/atomic-1.c
> gcc/testsuite/c-c++-common/gomp/atomic-1.c
> index 3e4bc569ba7..1facf4586f5 100644
> --- gcc/testsuite/c-c++-common/gomp/atomic-1.c
> +++ gcc/testsuite/c-c++-common/gomp/atomic-1.c
> @@ -1,4 +1,5 @@
> /* { dg-do compile } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
>
> int x;
> volatile int y;
> diff --git gcc/testsuite/c-c++-common/gomp/atomic-9.c
> gcc/testsuite/c-c++-common/gomp/atomic-9.c
> index c07da8fc712..35548395f36 100644
> --- gcc/testsuite/c-c++-common/gomp/atomic-9.c
> +++ gcc/testsuite/c-c++-common/gomp/atomic-9.c
> @@ -1,5 +1,6 @@
> /* { dg-do compile } */
> /* { dg-options "-fopenmp -fdump-tree-ompexp" } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
> /* { dg-require-effective-target cas_int } */
>
> volatile int *bar(void);
> diff --git gcc/testsuite/c-c++-common/gomp/depend-iterator-1.c
> gcc/testsuite/c-c++-common/gomp/depend-iterator-1.c
> index 4fb01c174ec..6fa60215f43 100644
> --- gcc/testsuite/c-c++-common/gomp/depend-iterator-1.c
> +++ gcc/testsuite/c-c++-common/gomp/depend-iterator-1.c
> @@ -1,3 +1,5 @@
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
> +
> int arr[64], arr2[64];
> struct S { int a[4]; } k;
> short arr4[4];
> diff --git gcc/testsuite/c-c++-common/gomp/loop-1.c
> gcc/testsuite/c-c++-common/gomp/loop-1.c
> index d2f943aea54..4fb995c02a7 100644
> --- gcc/testsuite/c-c++-common/gomp/loop-1.c
> +++ gcc/testsuite/c-c++-common/gomp/loop-1.c
> @@ -100,8 +100,8 @@ f4 (int *a)
> #pragma omp loop order(concurrent) bind(parallel)
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a 'loop'
> region" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" "" { target c } } */
> }
> #pragma omp loop order(concurrent) bind(parallel)
> for (i = 0; i < 64; i++)
> @@ -172,8 +172,8 @@ f5 (int *a)
> #pragma omp loop
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a 'loop'
> region" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" "" { target c } } */
> }
> #pragma omp loop
> for (i = 0; i < 64; i++)
> @@ -245,8 +245,8 @@ f6 (int *a)
> #pragma omp loop
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a 'loop'
> region" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> 'loop' region" "" { target c } } */
> }
> #pragma omp loop
> for (i = 0; i < 64; i++)
> diff --git gcc/testsuite/c-c++-common/gomp/order-3.c
> gcc/testsuite/c-c++-common/gomp/order-3.c
> index 2d51bf37749..e33386dd5cc 100644
> --- gcc/testsuite/c-c++-common/gomp/order-3.c
> +++ gcc/testsuite/c-c++-common/gomp/order-3.c
> @@ -50,8 +50,8 @@ f1 (int *a)
> #pragma omp simd order(concurrent)
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a region
> with the 'order\\(concurrent\\)' clause" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" "" { target c } } */
> }
> #pragma omp simd order(concurrent)
> for (i = 0; i < 64; i++)
> @@ -112,8 +112,8 @@ f2 (int *a)
> #pragma omp for simd order(concurrent)
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a region
> with the 'order\\(concurrent\\)' clause" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" "" { target c } } */
> }
> #pragma omp for simd order(concurrent)
> for (i = 0; i < 64; i++)
> @@ -174,8 +174,8 @@ f3 (int *a)
> #pragma omp for order(concurrent)
> for (i = 0; i < 64; i++)
> {
> - #pragma omp atomic read
> - a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" } */
> + #pragma omp atomic read /* { dg-error "OpenMP constructs
> other than 'parallel', 'loop' or 'simd' may not be nested inside a region
> with the 'order\\(concurrent\\)' clause" "" { target c++ } } */
> + a[i] = v; /* { dg-error "OpenMP
> constructs other than 'parallel', 'loop' or 'simd' may not be nested inside a
> region with the 'order\\(concurrent\\)' clause" "" { target c } } */
> }
> #pragma omp for order(concurrent)
> for (i = 0; i < 64; i++)
> diff --git gcc/testsuite/c-c++-common/pr69733.c
> gcc/testsuite/c-c++-common/pr69733.c
> index 57ec1eccb9f..ab70f49009c 100644
> --- gcc/testsuite/c-c++-common/pr69733.c
> +++ gcc/testsuite/c-c++-common/pr69733.c
> @@ -1,5 +1,6 @@
> /* { dg-do compile } */
> /* { dg-options "-W -fdiagnostics-show-caret" } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
>
> typedef const double cd;
> double val;
> @@ -21,4 +22,3 @@ cd val2() {return val;} /* { dg-warning "qualifiers
> ignored" } */
> cd val2() {return val;}
> ^~
> { dg-end-multiline-output "" } */
> -
> diff --git gcc/testsuite/c-c++-common/spec-barrier-2.c
> gcc/testsuite/c-c++-common/spec-barrier-2.c
> index b09567e62a9..a27ec54f0d3 100644
> --- gcc/testsuite/c-c++-common/spec-barrier-2.c
> +++ gcc/testsuite/c-c++-common/spec-barrier-2.c
> @@ -1,4 +1,5 @@
> /* { dg-do run } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
>
> /* Even on targets that don't need the optional failval parameter,
> side-effects on the operand should still be calculated. */
> diff --git gcc/testsuite/c-c++-common/tm/pr54893.c
> gcc/testsuite/c-c++-common/tm/pr54893.c
> index 3766078d31e..266cbe9c652 100644
> --- gcc/testsuite/c-c++-common/tm/pr54893.c
> +++ gcc/testsuite/c-c++-common/tm/pr54893.c
> @@ -1,5 +1,6 @@
> /* { dg-do compile } */
> /* { dg-options "-fgnu-tm -fdump-ipa-tmipa" } */
> +/* { dg-additional-options "-Wno-volatile" { target c++ } } */
>
> /* Test that volatiles are allowed inside relaxed transactions. */
>
> diff --git gcc/testsuite/g++.dg/cpp0x/pr65327.C
> gcc/testsuite/g++.dg/cpp0x/pr65327.C
> index 5176b3c3204..6e888ebff2c 100644
> --- gcc/testsuite/g++.dg/cpp0x/pr65327.C
> +++ gcc/testsuite/g++.dg/cpp0x/pr65327.C
> @@ -11,7 +11,7 @@ foo ()
> static constexpr volatile int k = 5;
> }
>
> -constexpr volatile int
> +constexpr volatile int // { dg-warning "deprecated" "" { target c++2a } }
> bar ()
> {
> return i;
> diff --git gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
> gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
> index 9b9b154995b..2f2a1fa702a 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv-conv2.C
> @@ -1,16 +1,16 @@
> // PR c++/89705
> // { dg-do compile { target c++11 } }
>
> -struct W { operator const volatile int(); };
> +struct W { operator const volatile int(); }; // { dg-warning "deprecated" ""
> { target c++2a } }
> const int& rci = W();
>
> struct X { operator const int(); };
> int&& rri = X();
>
> -struct Y { operator volatile int(); };
> +struct Y { operator volatile int(); }; // { dg-warning "deprecated" "" {
> target c++2a } }
> int&& rri2 = Y();
>
> -struct Z { operator const volatile int(); };
> +struct Z { operator const volatile int(); }; // { dg-warning "deprecated" ""
> { target c++2a } }
> volatile int&& rri3 = Z();
>
> enum E { A };
> diff --git gcc/testsuite/g++.dg/cpp0x/rv1n.C gcc/testsuite/g++.dg/cpp0x/rv1n.C
> index f5e75681758..a762fc85862 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv1n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv1n.C
> @@ -26,8 +26,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 1 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv1p.C gcc/testsuite/g++.dg/cpp0x/rv1p.C
> index a9097276d5a..e2a983a7708 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv1p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv1p.C
> @@ -26,8 +26,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 1 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv2n.C gcc/testsuite/g++.dg/cpp0x/rv2n.C
> index 65eda80fba0..2871ccf9ab3 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv2n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv2n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 2 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv2p.C gcc/testsuite/g++.dg/cpp0x/rv2p.C
> index 25a42ba2af8..bab0dce3d97 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv2p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv2p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 2 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv3n.C gcc/testsuite/g++.dg/cpp0x/rv3n.C
> index 4549438f8ef..35cdba95858 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv3n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv3n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 3 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv3p.C gcc/testsuite/g++.dg/cpp0x/rv3p.C
> index 2d7d78df6be..b25aa26c9b0 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv3p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv3p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 3 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv4n.C gcc/testsuite/g++.dg/cpp0x/rv4n.C
> index 29deb3fc81b..6941a13de6c 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv4n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv4n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 4 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv4p.C gcc/testsuite/g++.dg/cpp0x/rv4p.C
> index 0e4903bc291..cd0d631d780 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv4p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv4p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 4 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv5n.C gcc/testsuite/g++.dg/cpp0x/rv5n.C
> index f11d07a3921..086aa460c68 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv5n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv5n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 5 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv5p.C gcc/testsuite/g++.dg/cpp0x/rv5p.C
> index 63441a3f0da..34c1017f578 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv5p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv5p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 5 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv6n.C gcc/testsuite/g++.dg/cpp0x/rv6n.C
> index 0ebbe33e1d1..b21d22a5b87 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv6n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv6n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 6 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv6p.C gcc/testsuite/g++.dg/cpp0x/rv6p.C
> index 26714f0c9aa..fee692bb08f 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv6p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv6p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 6 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv7n.C gcc/testsuite/g++.dg/cpp0x/rv7n.C
> index d9e371b8adb..5bc313cc07f 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv7n.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv7n.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 7 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv7p.C gcc/testsuite/g++.dg/cpp0x/rv7p.C
> index 60a35835c7d..b0b8f965498 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv7p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv7p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 7 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/rv8p.C gcc/testsuite/g++.dg/cpp0x/rv8p.C
> index e12da4b8d79..287fb93b432 100644
> --- gcc/testsuite/g++.dg/cpp0x/rv8p.C
> +++ gcc/testsuite/g++.dg/cpp0x/rv8p.C
> @@ -25,8 +25,8 @@ struct A
>
> A source();
> const A c_source();
> - volatile A v_source();
> -const volatile A cv_source();
> + volatile A v_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
> +const volatile A cv_source(); // { dg-warning "deprecated" "" { target c++2a
> } }
>
> // 8 at a time
>
> diff --git gcc/testsuite/g++.dg/cpp0x/trailing14.C
> gcc/testsuite/g++.dg/cpp0x/trailing14.C
> index 2544d0bab5e..4ebb37406ad 100644
> --- gcc/testsuite/g++.dg/cpp0x/trailing14.C
> +++ gcc/testsuite/g++.dg/cpp0x/trailing14.C
> @@ -1,6 +1,6 @@
> // PR c++/65775
> // { dg-do compile { target c++11 } }
> -// { dg-options "-Wignored-qualifiers" }
> +// { dg-options "-Wignored-qualifiers -Wno-volatile" }
>
> using Qi = int const volatile;
> Qi q1(); // { dg-warning "1: type qualifiers ignored" }
> diff --git gcc/testsuite/g++.dg/cpp1y/new1.C gcc/testsuite/g++.dg/cpp1y/new1.C
> index 5e4f1bf6b0b..b9ad64dfcc0 100644
> --- gcc/testsuite/g++.dg/cpp1y/new1.C
> +++ gcc/testsuite/g++.dg/cpp1y/new1.C
> @@ -65,7 +65,7 @@ void
> test_unused() {
> volatile double d = 0.0;
> double *p = new double ();
> - d += 1.0;
> + d += 1.0; // { dg-warning "deprecated" "" { target c++2a } }
> delete p;
> }
>
> diff --git gcc/testsuite/g++.dg/cpp2a/volatile1.C
> gcc/testsuite/g++.dg/cpp2a/volatile1.C
> new file mode 100644
> index 00000000000..e47591b13bc
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp2a/volatile1.C
> @@ -0,0 +1,141 @@
> +// PR c++/91361 - P1152R4: Deprecating some uses of volatile.
> +// { dg-do compile { target c++17 } }
> +
> +#define ACCESS_ONCE(x) (*(volatile __typeof(x) *)&(x))
> +
> +struct S {
> + volatile int a : 4;
> + int b : 2;
> +};
> +
> +struct T {
> + int a : 4;
> + int b : 2;
> +};
> +
> +union U {
> + char c;
> + int i;
> +};
> +
> +struct W {
> + W();
> + W(volatile W&);
> + W& operator=(volatile W&) volatile;
> +};
> +
> +volatile int // { dg-warning ".volatile.-qualified return type is
> deprecated" "" { target c++2a } }
> +fn (volatile int i) // { dg-warning ".volatile.-qualified parameter is
> deprecated" "" { target c++2a } }
> +{
> + volatile int v = 10;
> + int *volatile p = nullptr;
> +
> + // Pre/post ++/--.
> + v++; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + ++v; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + v--; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + --v; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + p++; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + ++p; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + p--; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + --p; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" "" { target c++2a } }
> + return v + i + *p;
> +}
> +
> +void
> +fn2 ()
> +{
> + volatile int vi = 42;
> + int i = 24;
> +
> + // Discarded-value expression ([expr.context]).
> + // The lvalue-to-rvalue conversion is applied here:
> + vi;
> + // ...but not here. Otherwise we'd write to VI and then immediately read
> it.
> + vi = 42;
> + vi = i;
> + vi = i = 42;
> + i = vi = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + &(vi = i); // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + (vi = 42, 45);
> + (i = vi = 42, 10); // { dg-warning "assignment with .volatile.-qualified
> left operand is deprecated" "" { target c++2a } }
> + i = vi; // LHS not volatile.
> + i = (vi = i, 42);
> + static_cast<void>(vi = i);
> + static_cast<void>(i = vi = 42); // { dg-warning "assignment with
> .volatile.-qualified left operand is deprecated" "" { target c++2a } }
> + (void)(vi = i);
> + (void)(i = vi = 42); // { dg-warning "assignment with .volatile.-qualified
> left operand is deprecated" "" { target c++2a } }
> +
> + // Unevaluated operand.
> + decltype(vi = 42) x = vi;
> + decltype(i = vi = 42) x3 = i;
> +
> + // Compound assignments.
> + vi += i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi -= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi %= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi ^= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi |= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi /= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi = vi += 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + vi += vi = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + i *= vi;
> + decltype(vi -= 42) x2 = vi; // { dg-warning "assignment with
> .volatile.-qualified left operand is deprecated" "" { target c++2a } }
> +
> + // Structured bindings.
> + int a[] = { 10, 5 };
> + const auto & [cxr, cyr] = a;
> + const volatile auto & [cvxr, cvyr] = a; // { dg-warning
> ".volatile.-qualified structured binding is deprecated" "" { target c++2a } }
> + volatile auto & [vxr, vyr] = a; // { dg-warning ".volatile.-qualified
> structured binding is deprecated" "" { target c++2a } }
> +}
> +
> +void
> +fn3 ()
> +{
> + volatile int i, j, k = 0;
> + i = j = k; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> +
> + ACCESS_ONCE(j);
> +
> + S s;
> + s.b = 1;
> +
> + volatile U u;
> + u.c = 42;
> + i = u.c = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + u.c += 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> +
> + volatile T t;
> + t.a = 3;
> + j = t.a = 3; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + t.a += 3; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> +
> + volatile int *src = &i;
> + *src; // No assignment, don't warn.
> +}
> +
> +void
> +fn4 ()
> +{
> + volatile W vw;
> + W w;
> + // Assignment to objects of a class is defined by the copy/move assignment
> + // operator.
> + vw = w;
> + w = vw;
> +}
> +
> +template<typename T>
> +void raccoon ()
> +{
> + volatile T t, u;
> + t = 42;
> + u = t = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> + t &= 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" "" { target c++2a } }
> +}
> +
> +void
> +fn5 ()
> +{
> + raccoon<int>();
> +}
> diff --git gcc/testsuite/g++.dg/cpp2a/volatile2.C
> gcc/testsuite/g++.dg/cpp2a/volatile2.C
> new file mode 100644
> index 00000000000..1a7889a6a8c
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp2a/volatile2.C
> @@ -0,0 +1,142 @@
> +// PR c++/91361 - P1152R4: Deprecating some uses of volatile.
> +// { dg-do compile { target c++2a } }
> +// { dg-options "-Wno-volatile" }
> +
> +#define ACCESS_ONCE(x) (*(volatile __typeof(x) *)&(x))
> +
> +struct S {
> + volatile int a : 4;
> + int b : 2;
> +};
> +
> +struct T {
> + int a : 4;
> + int b : 2;
> +};
> +
> +union U {
> + char c;
> + int i;
> +};
> +
> +struct W {
> + W();
> + W(volatile W&);
> + W& operator=(volatile W&) volatile;
> +};
> +
> +volatile int
> +fn (volatile int i)
> +{
> + volatile int v = 10;
> + int *volatile p = nullptr;
> +
> + // Pre/post ++/--.
> + v++;
> + ++v;
> + v--;
> + --v;
> + p++;
> + ++p;
> + p--;
> + --p;
> + return v + i + *p;
> +}
> +
> +void
> +fn2 ()
> +{
> + volatile int vi = 42;
> + int i = 24;
> +
> + // Discarded-value expression ([expr.context]).
> + // The lvalue-to-rvalue conversion is applied here:
> + vi;
> + // ...but not here. Otherwise we'd write to VI and then immediately read
> it.
> + vi = 42;
> + vi = i;
> + vi = i = 42;
> + i = vi = 42;
> + &(vi = i);
> + (vi = 42, 45);
> + (i = vi = 42, 10);
> + i = vi; // LHS not volatile.
> + i = (vi = i, 42);
> + static_cast<void>(vi = i);
> + static_cast<void>(i = vi = 42);
> + (void)(vi = i);
> + (void)(i = vi = 42);
> +
> + // Unevaluated operand.
> + decltype(vi = 42) x = vi;
> + decltype(i = vi = 42) x3 = i;
> +
> + // Compound assignments.
> + vi += i;
> + vi -= i;
> + vi %= i;
> + vi ^= i;
> + vi |= i;
> + vi /= i;
> + vi = vi += 42;
> + vi += vi = 42;
> + i *= vi;
> + decltype(vi -= 42) x2 = vi;
> +
> + // Structured bindings.
> + int a[] = { 10, 5 };
> + const auto & [cxr, cyr] = a;
> + const volatile auto & [cvxr, cvyr] = a;
> + volatile auto & [vxr, vyr] = a;
> +}
> +
> +void
> +fn3 ()
> +{
> + volatile int i, j, k = 0;
> + i = j = k;
> +
> + ACCESS_ONCE(j);
> +
> + S s;
> + s.b = 1;
> +
> + volatile U u;
> + u.c = 42;
> + i = u.c = 42;
> + u.c += 42;
> +
> + volatile T t;
> + t.a = 3;
> + j = t.a = 3;
> + t.a += 3;
> +
> + volatile int *src = &i;
> + *src; // No assignment, don't warn.
> +}
> +
> +void
> +fn4 ()
> +{
> + volatile W vw;
> + W w;
> + // Assignment to objects of a class is defined by the copy/move assignment
> + // operator.
> + vw = w;
> + w = vw;
> +}
> +
> +template<typename T>
> +void raccoon ()
> +{
> + volatile T t, u;
> + t = 42;
> + u = t = 42;
> + t &= 42;
> +}
> +
> +void
> +fn5 ()
> +{
> + raccoon<int>();
> +}
> diff --git gcc/testsuite/g++.dg/cpp2a/volatile3.C
> gcc/testsuite/g++.dg/cpp2a/volatile3.C
> new file mode 100644
> index 00000000000..f10a29756a9
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp2a/volatile3.C
> @@ -0,0 +1,142 @@
> +// PR c++/91361 - P1152R4: Deprecating some uses of volatile.
> +// { dg-do compile { target c++17 } }
> +// { dg-options "-Wvolatile" }
> +
> +#define ACCESS_ONCE(x) (*(volatile __typeof(x) *)&(x))
> +
> +struct S {
> + volatile int a : 4;
> + int b : 2;
> +};
> +
> +struct T {
> + int a : 4;
> + int b : 2;
> +};
> +
> +union U {
> + char c;
> + int i;
> +};
> +
> +struct W {
> + W();
> + W(volatile W&);
> + W& operator=(volatile W&) volatile;
> +};
> +
> +volatile int // { dg-warning ".volatile.-qualified return type is
> deprecated" }
> +fn (volatile int i) // { dg-warning ".volatile.-qualified parameter is
> deprecated" }
> +{
> + volatile int v = 10;
> + int *volatile p = nullptr;
> +
> + // Pre/post ++/--.
> + v++; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + ++v; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + v--; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + --v; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + p++; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + ++p; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + p--; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + --p; // { dg-warning "expression of .volatile.-qualified type is
> deprecated" }
> + return v + i + *p;
> +}
> +
> +void
> +fn2 ()
> +{
> + volatile int vi = 42;
> + int i = 24;
> +
> + // Discarded-value expression ([expr.context]).
> + // The lvalue-to-rvalue conversion is applied here:
> + vi;
> + // ...but not here. Otherwise we'd write to VI and then immediately read
> it.
> + vi = 42;
> + vi = i;
> + vi = i = 42;
> + i = vi = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + &(vi = i); // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + (vi = 42, 45);
> + (i = vi = 42, 10); // { dg-warning "assignment with .volatile.-qualified
> left operand is deprecated" }
> + i = vi; // LHS not volatile.
> + i = (vi = i, 42);
> + static_cast<void>(vi = i);
> + static_cast<void>(i = vi = 42); // { dg-warning "assignment with
> .volatile.-qualified left operand is deprecated" }
> + (void)(vi = i);
> + (void)(i = vi = 42); // { dg-warning "assignment with .volatile.-qualified
> left operand is deprecated" }
> +
> + // Unevaluated operand.
> + decltype(vi = 42) x = vi;
> + decltype(i = vi = 42) x3 = i;
> +
> + // Compound assignments.
> + vi += i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi -= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi %= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi ^= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi |= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi /= i; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi = vi += 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + vi += vi = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + i *= vi;
> + decltype(vi -= 42) x2 = vi; // { dg-warning "assignment with
> .volatile.-qualified left operand is deprecated" }
> +
> + // Structured bindings.
> + int a[] = { 10, 5 };
> + const auto & [cxr, cyr] = a;
> + const volatile auto & [cvxr, cvyr] = a; // { dg-warning
> ".volatile.-qualified structured binding is deprecated" }
> + volatile auto & [vxr, vyr] = a; // { dg-warning ".volatile.-qualified
> structured binding is deprecated" }
> +}
> +
> +void
> +fn3 ()
> +{
> + volatile int i, j, k = 0;
> + i = j = k; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> +
> + ACCESS_ONCE(j);
> +
> + S s;
> + s.b = 1;
> +
> + volatile U u;
> + u.c = 42;
> + i = u.c = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + u.c += 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> +
> + volatile T t;
> + t.a = 3;
> + j = t.a = 3; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + t.a += 3; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> +
> + volatile int *src = &i;
> + *src; // No assignment, don't warn.
> +}
> +
> +void
> +fn4 ()
> +{
> + volatile W vw;
> + W w;
> + // Assignment to objects of a class is defined by the copy/move assignment
> + // operator.
> + vw = w;
> + w = vw;
> +}
> +
> +template<typename T>
> +void raccoon ()
> +{
> + volatile T t, u;
> + t = 42;
> + u = t = 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> + t &= 42; // { dg-warning "assignment with .volatile.-qualified left
> operand is deprecated" }
> +}
> +
> +void
> +fn5 ()
> +{
> + raccoon<int>();
> +}
> diff --git gcc/testsuite/g++.dg/cpp2a/volatile4.C
> gcc/testsuite/g++.dg/cpp2a/volatile4.C
> new file mode 100644
> index 00000000000..2148cdeb3d1
> --- /dev/null
> +++ gcc/testsuite/g++.dg/cpp2a/volatile4.C
> @@ -0,0 +1,142 @@
> +// PR c++/91361 - P1152R4: Deprecating some uses of volatile.
> +// { dg-do compile { target c++2a } }
> +// { dg-options "-Wno-deprecated" }
> +
> +#define ACCESS_ONCE(x) (*(volatile __typeof(x) *)&(x))
> +
> +struct S {
> + volatile int a : 4;
> + int b : 2;
> +};
> +
> +struct T {
> + int a : 4;
> + int b : 2;
> +};
> +
> +union U {
> + char c;
> + int i;
> +};
> +
> +struct W {
> + W();
> + W(volatile W&);
> + W& operator=(volatile W&) volatile;
> +};
> +
> +volatile int
> +fn (volatile int i)
> +{
> + volatile int v = 10;
> + int *volatile p = nullptr;
> +
> + // Pre/post ++/--.
> + v++;
> + ++v;
> + v--;
> + --v;
> + p++;
> + ++p;
> + p--;
> + --p;
> + return v + i + *p;
> +}
> +
> +void
> +fn2 ()
> +{
> + volatile int vi = 42;
> + int i = 24;
> +
> + // Discarded-value expression ([expr.context]).
> + // The lvalue-to-rvalue conversion is applied here:
> + vi;
> + // ...but not here. Otherwise we'd write to VI and then immediately read
> it.
> + vi = 42;
> + vi = i;
> + vi = i = 42;
> + i = vi = 42;
> + &(vi = i);
> + (vi = 42, 45);
> + (i = vi = 42, 10);
> + i = vi; // LHS not volatile.
> + i = (vi = i, 42);
> + static_cast<void>(vi = i);
> + static_cast<void>(i = vi = 42);
> + (void)(vi = i);
> + (void)(i = vi = 42);
> +
> + // Unevaluated operand.
> + decltype(vi = 42) x = vi;
> + decltype(i = vi = 42) x3 = i;
> +
> + // Compound assignments.
> + vi += i;
> + vi -= i;
> + vi %= i;
> + vi ^= i;
> + vi |= i;
> + vi /= i;
> + vi = vi += 42;
> + vi += vi = 42;
> + i *= vi;
> + decltype(vi -= 42) x2 = vi;
> +
> + // Structured bindings.
> + int a[] = { 10, 5 };
> + const auto & [cxr, cyr] = a;
> + const volatile auto & [cvxr, cvyr] = a;
> + volatile auto & [vxr, vyr] = a;
> +}
> +
> +void
> +fn3 ()
> +{
> + volatile int i, j, k = 0;
> + i = j = k;
> +
> + ACCESS_ONCE(j);
> +
> + S s;
> + s.b = 1;
> +
> + volatile U u;
> + u.c = 42;
> + i = u.c = 42;
> + u.c += 42;
> +
> + volatile T t;
> + t.a = 3;
> + j = t.a = 3;
> + t.a += 3;
> +
> + volatile int *src = &i;
> + *src; // No assignment, don't warn.
> +}
> +
> +void
> +fn4 ()
> +{
> + volatile W vw;
> + W w;
> + // Assignment to objects of a class is defined by the copy/move assignment
> + // operator.
> + vw = w;
> + w = vw;
> +}
> +
> +template<typename T>
> +void raccoon ()
> +{
> + volatile T t, u;
> + t = 42;
> + u = t = 42;
> + t &= 42;
> +}
> +
> +void
> +fn5 ()
> +{
> + raccoon<int>();
> +}
> diff --git gcc/testsuite/g++.dg/expr/bool3.C gcc/testsuite/g++.dg/expr/bool3.C
> index 373c202b800..f27399cfc8a 100644
> --- gcc/testsuite/g++.dg/expr/bool3.C
> +++ gcc/testsuite/g++.dg/expr/bool3.C
> @@ -13,8 +13,10 @@ int main()
>
> b++; // { dg-warning "deprecated" "" { target { ! c++17 } } }
> // { dg-error "forbidden" "" { target c++17 } .-1 }
> + // { dg-warning ".volatile.-qualified type is deprecated" "" { target
> c++2a } .-2 }
> b++; // { dg-warning "deprecated" "" { target { ! c++17 } } }
> // { dg-error "forbidden" "" { target c++17 } .-1 }
> + // { dg-warning ".volatile.-qualified type is deprecated" "" { target
> c++2a } .-2 }
> i = b;
> if (i != 1)
> abort ();
> diff --git gcc/testsuite/g++.dg/expr/bool4.C gcc/testsuite/g++.dg/expr/bool4.C
> index dce51ec332e..5891bc311bd 100644
> --- gcc/testsuite/g++.dg/expr/bool4.C
> +++ gcc/testsuite/g++.dg/expr/bool4.C
> @@ -8,6 +8,6 @@ int main()
> {
> my_bool b = false;
> b--; // { dg-error "" }
> + // { dg-warning ".volatile.-qualified type is deprecated" "" { target
> c++2a } .-1 }
> return 0;
> }
> -
> diff --git gcc/testsuite/g++.dg/expr/cond9.C gcc/testsuite/g++.dg/expr/cond9.C
> index b344c1f683a..f7e092e1445 100644
> --- gcc/testsuite/g++.dg/expr/cond9.C
> +++ gcc/testsuite/g++.dg/expr/cond9.C
> @@ -4,7 +4,7 @@ struct A { // { dg-message "A" }
> A(int);
> };
>
> -void foo(volatile A a) {
> +void foo(volatile A a) { // { dg-warning "deprecated" "" { target c++2a } }
> 1 ? a : 0; // { dg-error "qualifiers|lvalue|no match" }
> 1 ? 0 : a; // { dg-error "qualifiers|lvalue|no match" }
> }
> diff --git gcc/testsuite/g++.dg/ext/vector25.C
> gcc/testsuite/g++.dg/ext/vector25.C
> index 6c1f5d09878..339865d6942 100644
> --- gcc/testsuite/g++.dg/ext/vector25.C
> +++ gcc/testsuite/g++.dg/ext/vector25.C
> @@ -2,5 +2,5 @@ volatile int i __attribute__((vector_size(8)));
>
> void foo()
> {
> - i += i;
> + i += i; // { dg-warning "deprecated" "" { target c++2a } }
> }
> diff --git gcc/testsuite/g++.dg/gomp/depend-iterator-1.C
> gcc/testsuite/g++.dg/gomp/depend-iterator-1.C
> index 6f4aa97ee44..d12670c5159 100644
> --- gcc/testsuite/g++.dg/gomp/depend-iterator-1.C
> +++ gcc/testsuite/g++.dg/gomp/depend-iterator-1.C
> @@ -1,3 +1,5 @@
> +// { dg-additional-options "-Wno-volatile" }
> +
> int arr[64], arr2[64];
> struct S { int a[4]; } k;
> short arr4[4];
> diff --git gcc/testsuite/g++.dg/inherit/covariant21.C
> gcc/testsuite/g++.dg/inherit/covariant21.C
> index 42cdf870081..769cb14ecbc 100644
> --- gcc/testsuite/g++.dg/inherit/covariant21.C
> +++ gcc/testsuite/g++.dg/inherit/covariant21.C
> @@ -6,12 +6,12 @@ struct C : A, B {};
>
> struct X
> {
> - virtual B* foo(volatile int);
> + virtual B* foo(volatile int); // { dg-warning "deprecated" "" { target
> c++2a } }
> };
>
> struct Y : X
> {
> - virtual C* foo(volatile int);
> + virtual C* foo(volatile int); // { dg-warning "deprecated" "" { target
> c++2a } }
> };
>
> -C* Y::foo(volatile int) { return 0; }
> +C* Y::foo(volatile int) { return 0; } // { dg-warning "deprecated" "" {
> target c++2a } }
> diff --git gcc/testsuite/g++.dg/init/ref18.C gcc/testsuite/g++.dg/init/ref18.C
> index e704077c26b..81ac76a40d3 100644
> --- gcc/testsuite/g++.dg/init/ref18.C
> +++ gcc/testsuite/g++.dg/init/ref18.C
> @@ -1,6 +1,6 @@
> // PR c++/49395
>
> -volatile int foo();
> +volatile int foo(); // { dg-warning "deprecated" "" { target c++2a } }
> struct A { volatile int i; };
> typedef volatile int vi;
>
> diff --git gcc/testsuite/g++.dg/ipa/pr63838.C
> gcc/testsuite/g++.dg/ipa/pr63838.C
> index d23b3133748..5b6b11d70e5 100644
> --- gcc/testsuite/g++.dg/ipa/pr63838.C
> +++ gcc/testsuite/g++.dg/ipa/pr63838.C
> @@ -7,12 +7,12 @@
> __attribute__((noinline, noclone)) static void bar (int);
> volatile int v;
> void (*fn) ();
> -struct S { S () { v++; } ~S () { v++; } };
> +struct S { S () { v++; } ~S () { v++; } }; // { dg-warning "deprecated" "" {
> target c++2a } }
>
> __attribute__((noinline, noclone)) static void
> foo (int x)
> {
> - v++;
> + v++; // { dg-warning "deprecated" "" { target c++2a } }
> if (x == 5)
> bar (x);
> }
> @@ -20,7 +20,7 @@ foo (int x)
> __attribute__((noinline, noclone)) static void
> bar (int x)
> {
> - v++;
> + v++; // { dg-warning "deprecated" "" { target c++2a } }
> if (x == 6)
> foo (x);
> else if (x == 5)
> diff --git gcc/testsuite/g++.dg/overload/rvalue2.C
> gcc/testsuite/g++.dg/overload/rvalue2.C
> index 8a2290dc293..a829fb5e8cc 100644
> --- gcc/testsuite/g++.dg/overload/rvalue2.C
> +++ gcc/testsuite/g++.dg/overload/rvalue2.C
> @@ -7,5 +7,5 @@ template <class T> void f(const T&);
> int main()
> {
> volatile int i = 0;
> - f(i++);
> + f(i++); // { dg-warning "deprecated" "" { target c++2a } }
> }
> diff --git gcc/testsuite/g++.dg/parse/semicolon4.C
> gcc/testsuite/g++.dg/parse/semicolon4.C
> index 5135ec14b1f..bdd1c845187 100644
> --- gcc/testsuite/g++.dg/parse/semicolon4.C
> +++ gcc/testsuite/g++.dg/parse/semicolon4.C
> @@ -25,7 +25,7 @@ struct E1
> } const; // { dg-error "'const' can only be specified
> for objects and functions" }
>
> void foo (
> -struct E2
> +struct E2 // { dg-warning "deprecated" "" { target
> c++2a } }
> { // { dg-error "types may not be defined in
> parameter types" }
> int i;
> } volatile);
> diff --git gcc/testsuite/g++.dg/warn/Wreturn-type-4.C
> gcc/testsuite/g++.dg/warn/Wreturn-type-4.C
> index 4f02678e7f9..24a6b41cbd8 100644
> --- gcc/testsuite/g++.dg/warn/Wreturn-type-4.C
> +++ gcc/testsuite/g++.dg/warn/Wreturn-type-4.C
> @@ -3,6 +3,7 @@
> /* { dg-options "-Wignored-qualifiers" } */
>
> volatile void bar(); /* { dg-warning "type qualifiers ignored" } */
> +// { dg-warning ".volatile.-qualified return type is deprecated" "" { target
> c++2a } .-1 }
>
> struct A
> {
> diff --git gcc/testsuite/g++.dg/warn/pr36069.C
> gcc/testsuite/g++.dg/warn/pr36069.C
> index efb35c25716..7b166351a4b 100644
> --- gcc/testsuite/g++.dg/warn/pr36069.C
> +++ gcc/testsuite/g++.dg/warn/pr36069.C
> @@ -6,11 +6,13 @@ struct foo {
> bool a;
> volatile bool b,c;
> foo() { a = b = c = false; } // { dg-bogus "parentheses" }
> + // { dg-warning "deprecated" "" { target c++2a } .-1 }
> };
>
> int main() {
> bool a;
> volatile bool b,c;
> a = b = c = false; // { dg-bogus "parentheses" }
> + // { dg-warning "deprecated" "" { target c++2a } .-1 }
> foo A;
> }
> diff --git gcc/testsuite/g++.old-deja/g++.mike/p9506.C
> gcc/testsuite/g++.old-deja/g++.mike/p9506.C
> index db16e3738e2..97594640f96 100644
> --- gcc/testsuite/g++.old-deja/g++.mike/p9506.C
> +++ gcc/testsuite/g++.old-deja/g++.mike/p9506.C
> @@ -3,5 +3,5 @@
>
> char * volatile p;
> void foo() {
> - --p = 0;
> + --p = 0; // { dg-warning "deprecated" "" { target c++2a } }
> }
> diff --git gcc/testsuite/g++.old-deja/g++.other/volatile1.C
> gcc/testsuite/g++.old-deja/g++.other/volatile1.C
> index 7d818fbe9e1..a93ef58aa9f 100644
> --- gcc/testsuite/g++.old-deja/g++.other/volatile1.C
> +++ gcc/testsuite/g++.old-deja/g++.other/volatile1.C
> @@ -5,7 +5,7 @@
> class f_class // { dg-message "note" "candidates" }
> { };
>
> -volatile f_class
> +volatile f_class // { dg-warning "deprecated" "" { target c++2a
> } }
> ret_v_f_class()
> {
> f_class t;
