The C++ bits look good to my casual non-maintainer eyes. Let's CC
Jason.
Thanks.
Jonathan Wakely <jwakely....@gmail.com> a écrit:
> This adds a warning switch for the existing "returning address of
> local variable" warnings in the C and C++ FEs which are enabled by
> default but have no switch controlling them. Adding a switch allows it
> to be turned into an error with -Werror=return-local-addr. I've added
> two tests checking the -Werror form works.
>
> gcc/c-family:
> PR c++/54930
> * c.opt (Wreturn_local_addr): Define new option.
>
> gcc/c:
> PR c++/54930
> * c-typeck.c (c_finish_return): Use OPT_Wreturn_local_addr.
>
> gcc/cp:
> PR c++/54930
> * typeck.c (maybe_warn_about_returning_address_of_local): Use
> OPT_Wreturn_local_addr.
>
> gcc:
> PR c++/54930
> * doc/invoke.texi (Warning Options): Document -Wno-return-local-addr.
>
> gcc/testsuite:
> PR c++/54930
> * gcc.dg/Wreturn-local-addr.c: New.
> * g++.dg/warn/Wno-return-local-addr.C: New.
> * g++.dg/warn/Wreturn-local-addr.C: New.
>
> Tested x86_64-linux, OK for trunk?
>
> commit 77abe727e837e052680be8020fa2990cce4d1e9a
> Author: Jonathan Wakely <jwakely....@gmail.com>
> Date: Wed Oct 17 19:32:10 2012 +0100
>
> gcc/c-family:
> PR c++/54930
> * c.opt (Wreturn_local_addr): Define new option.
>
> gcc/c:
> PR c++/54930
> * c-typeck.c (c_finish_return): Use OPT_Wreturn_local_addr.
>
> gcc/cp:
> PR c++/54930
> * typeck.c (maybe_warn_about_returning_address_of_local): Use
> OPT_Wreturn_local_addr.
>
> gcc:
> PR c++/54930
> * doc/invoke.texi (Warning Options): Document -Wno-return-local-addr.
>
> gcc/testsuite:
> PR c++/54930
> * gcc.dg/Wreturn-local-addr.c: New.
> * g++.dg/warn/Wno-return-local-addr.C: New.
> * g++.dg/warn/Wreturn-local-addr.C: New.
>
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index 3166984..f75b58c 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -601,6 +601,10 @@ Wreorder
> C++ ObjC++ Var(warn_reorder) Warning LangEnabledBy(C++ ObjC++,Wall)
> Warn when the compiler reorders code
>
> +Wreturn-local-addr
> +C ObjC C++ ObjC++ Var(warn_return_local_addr) Init(1) Warning
> +Warn about returning a pointer/reference to a local or temporary variable.
> +
> Wreturn-type
> C ObjC C++ ObjC++ Var(warn_return_type) Warning
> Warn whenever a function's return type defaults to \"int\" (C), or about
> inconsistent return types (C++)
> diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
> index 4855933..cf63355 100644
> --- a/gcc/c/c-typeck.c
> +++ b/gcc/c/c-typeck.c
> @@ -8742,7 +8742,8 @@ c_finish_return (location_t loc, tree retval, tree
> origtype)
> && !TREE_STATIC (inner)
> && DECL_CONTEXT (inner) == current_function_decl)
> warning_at (loc,
> - 0, "function returns address of local variable");
> + OPT_Wreturn_local_addr, "function returns address "
> + "of local variable");
> break;
>
> default:
> diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
> index eaa0935..d2944d3 100644
> --- a/gcc/cp/typeck.c
> +++ b/gcc/cp/typeck.c
> @@ -8019,14 +8019,14 @@ maybe_warn_about_returning_address_of_local (tree
> retval)
> if (TREE_CODE (whats_returned) == AGGR_INIT_EXPR
> || TREE_CODE (whats_returned) == TARGET_EXPR)
> {
> - warning (0, "returning reference to temporary");
> + warning (OPT_Wreturn_local_addr, "returning reference to temporary");
> return;
> }
> if (TREE_CODE (whats_returned) == VAR_DECL
> && DECL_NAME (whats_returned)
> && TEMP_NAME_P (DECL_NAME (whats_returned)))
> {
> - warning (0, "reference to non-lvalue returned");
> + warning (OPT_Wreturn_local_addr, "reference to non-lvalue returned");
> return;
> }
> }
> @@ -8042,10 +8042,10 @@ maybe_warn_about_returning_address_of_local (tree
> retval)
> || TREE_PUBLIC (whats_returned)))
> {
> if (TREE_CODE (valtype) == REFERENCE_TYPE)
> - warning (0, "reference to local variable %q+D returned",
> + warning (OPT_Wreturn_local_addr, "reference to local variable %q+D
> returned",
> whats_returned);
> else
> - warning (0, "address of local variable %q+D returned",
> + warning (OPT_Wreturn_local_addr, "address of local variable %q+D
> returned",
> whats_returned);
> return;
> }
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index f8c9230..2e36de1 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -261,7 +261,7 @@ Objective-C and Objective-C++ Dialects}.
> -Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded @gol
> -Wparentheses -Wpedantic-ms-format -Wno-pedantic-ms-format @gol
> -Wpointer-arith -Wno-pointer-to-int-cast @gol
> --Wredundant-decls @gol
> +-Wredundant-decls -Wno-return-local-addr @gol
> -Wreturn-type -Wsequence-point -Wshadow @gol
> -Wsign-compare -Wsign-conversion -Wsizeof-pointer-memaccess @gol
> -Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol
> @@ -3526,6 +3526,12 @@ definitions, may be found on the GCC readings page, at
>
> This warning is enabled by @option{-Wall} for C and C++.
>
> +@item -Wno-return-local-addr
> +@opindex Wno-return-local-addr
> +@opindex Wreturn-local-addr
> +Do not warn about returning a pointer (or in C++, a reference) to a
> +variable that goes out of scope after the function returns.
> +
> @item -Wreturn-type
> @opindex Wreturn-type
> @opindex Wno-return-type
> diff --git a/gcc/testsuite/g++.dg/warn/Wno-return-local-addr.C
> b/gcc/testsuite/g++.dg/warn/Wno-return-local-addr.C
> new file mode 100644
> index 0000000..e15bfa2
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wno-return-local-addr.C
> @@ -0,0 +1,26 @@
> +// { dg-do assemble }
> +// { dg-options "-Wno-return-local-addr" }
> +
> +int& bad1()
> +{
> + int x = 0;
> + return x;
> +}
> +
> +int* bad2()
> +{
> + int x = 0;
> + return &x;
> +}
> +
> +int f();
> +
> +const int& bad3()
> +{
> + return f();
> +}
> +
> +const int& bad4()
> +{
> + return int();
> +}
> diff --git a/gcc/testsuite/g++.dg/warn/Wreturn-local-addr.C
> b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr.C
> new file mode 100644
> index 0000000..faa3a34
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr.C
> @@ -0,0 +1,20 @@
> +// { dg-do assemble }
> +// { dg-options "-Werror=return-local-addr" }
> +// { dg-message "some warnings being treated as errors" "" {target "*-*-*"}
> 0 }
> +
> +int& bad1()
> +{
> + int x = 0; // { dg-error "reference to local variable" }
> + return x;
> +}
> +
> +int* bad2()
> +{
> + int x = 0; // { dg-error "address of local variable" }
> + return &x;
> +}
> +
> +const int& bad4()
> +{
> + return int(); // { dg-error "returning reference to
> temporary" }
> +}
> diff --git a/gcc/testsuite/gcc.dg/Wreturn-local-addr.c
> b/gcc/testsuite/gcc.dg/Wreturn-local-addr.c
> new file mode 100644
> index 0000000..d496d20
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/Wreturn-local-addr.c
> @@ -0,0 +1,9 @@
> +/* { dg-do assemble } */
> +/* { dg-options "-Werror=return-local-addr" } */
> +/* { dg-message "some warnings being treated as errors" "" {target "*-*-*"}
> 0 } */
> +
> +int* bad()
> +{
> + int x = 0;
> + return &x; /* { dg-error "address of local variable" } */
> +}
--
Dodji
