On 5/29/24 09:58, Julian Waters wrote:
Currently, gcc warns about noreturn marked functions that return both
explicitly and implicitly, with no way to turn this warning off. clang does
have an option for these classes of warnings, -Winvalid-noreturn. However, we
can do better. Instead of just having 1 option that switches the warnings for
both on and off, we can define an extra layer of granularity, and have a
separate options for implicit returns and explicit returns, as in
-Winvalid-return=explicit and -Winvalid-noreturn=implicit. This patch adds both
to gcc, for compatibility with clang.
Thanks!
Do note that I am relatively new to gcc's codebase, and as such couldn't figure
out how to cleanly define a general -Winvalid-noreturn warning that switch both
on and off, for better compatibility with clang. If someone should point out
how to do so, I'll happily rewrite my patch.
See -fstrong-eval-order for an example of an option that can be used
with or without =arg.
I also do not have write access to gcc, and will need help pushing this patch
once the green light is given
Good to know, I can take care of that.
best regards,
Julian
gcc/c-family/ChangeLog:
* c.opt: Introduce -Winvalid-noreturn=explicit and
-Winvalid-noreturn=implicit
gcc/ChangeLog:
* tree-cfg.cc (pass_warn_function_return::execute): Use it
gcc/c/ChangeLog:
* c-typeck.cc (c_finish_return): Use it
* gimple-parser.cc (c_finish_gimple_return): Use it
gcc/config/mingw/ChangeLog:
* mingw32.h (EXTRA_OS_CPP_BUILTINS): Fix semicolons
gcc/cp/ChangeLog:
* coroutines.cc (finish_co_return_stmt): Use it
* typeck.cc (check_return_expr): Use it
gcc/doc/ChangeLog:
* invoke.texi: Document new options
From 4daf884f8bbc1e318ba93121a6fdf4139da80b64 Mon Sep 17 00:00:00 2001
From: TheShermanTanker <tanksherma...@gmail.com>
Date: Wed, 29 May 2024 21:32:08 +0800
Subject: [PATCH] Introduce the -Winvalid-noreturn flag from clang with extra
tuneability
The rationale and ChangeLog entries should be part of the commit message
(and so the git format-patch output).
Signed-off-by: TheShermanTanker <tanksherma...@gmail.com>
A DCO sign-off can't use a pseudonym, sorry; please either sign off
using your real name or file a copyright assignment for the pseudonym
with the FSF.
See https://gcc.gnu.org/contribute.html#legal for more detail.
---
gcc/c-family/c.opt | 8 ++++++++
gcc/c/c-typeck.cc | 2 +-
gcc/c/gimple-parser.cc | 2 +-
gcc/config/mingw/mingw32.h | 6 +++---
gcc/cp/coroutines.cc | 2 +-
gcc/cp/typeck.cc | 2 +-
gcc/doc/invoke.texi | 13 +++++++++++++
gcc/tree-cfg.cc | 2 +-
8 files changed, 29 insertions(+), 8 deletions(-)
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index fb34c3b7031..32a2859fdcc 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -886,6 +886,14 @@ Winvalid-constexpr
C++ ObjC++ Var(warn_invalid_constexpr) Init(-1) Warning
Warn when a function never produces a constant expression.
+Winvalid-noreturn=explicit
+C ObjC C++ ObjC++ Warning
+Warn when a function marked noreturn returns explicitly.
+
+Winvalid-noreturn=implicit
+C ObjC C++ ObjC++ Warning
+Warn when a function marked noreturn returns implicitly.
+
Winvalid-offsetof
C++ ObjC++ Var(warn_invalid_offsetof) Init(1) Warning
Warn about invalid uses of the \"offsetof\" macro.
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index ad4c7add562..1941fbc44cb 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -11468,7 +11468,7 @@ c_finish_return (location_t loc, tree retval, tree
origtype)
location_t xloc = expansion_point_location_if_in_system_header (loc);
if (TREE_THIS_VOLATILE (current_function_decl))
- warning_at (xloc, 0,
+ warning_at (xloc, OPT_Winvalid_noreturn_explicit,
"function declared %<noreturn%> has a %<return%> statement");
if (retval)
diff --git a/gcc/c/gimple-parser.cc b/gcc/c/gimple-parser.cc
index d156d83cd37..1acaf75f844 100644
--- a/gcc/c/gimple-parser.cc
+++ b/gcc/c/gimple-parser.cc
@@ -2593,7 +2593,7 @@ c_finish_gimple_return (location_t loc, tree retval)
location_t xloc = expansion_point_location_if_in_system_header (loc);
if (TREE_THIS_VOLATILE (current_function_decl))
- warning_at (xloc, 0,
+ warning_at (xloc, OPT_Winvalid_noreturn_explicit,
"function declared %<noreturn%> has a %<return%> statement");
if (! retval)
diff --git a/gcc/config/mingw/mingw32.h b/gcc/config/mingw/mingw32.h
index fa6e307476c..a69926133b1 100644
--- a/gcc/config/mingw/mingw32.h
+++ b/gcc/config/mingw/mingw32.h
@@ -35,9 +35,9 @@ along with GCC; see the file COPYING3. If not see
| MASK_MS_BITFIELD_LAYOUT)
#ifdef TARGET_USING_MCFGTHREAD
-#define DEFINE_THREAD_MODEL builtin_define ("__USING_MCFGTHREAD__");
+#define DEFINE_THREAD_MODEL builtin_define ("__USING_MCFGTHREAD__")
#elif defined(TARGET_USE_PTHREAD_BY_DEFAULT)
-#define DEFINE_THREAD_MODEL builtin_define ("__USING_POSIXTHREAD__");
+#define DEFINE_THREAD_MODEL builtin_define ("__USING_POSIXTHREAD__")
#else
#define DEFINE_THREAD_MODEL
#endif
@@ -60,7 +60,7 @@ along with GCC; see the file COPYING3. If not see
builtin_define_std ("WIN64"); \
builtin_define ("_WIN64"); \
} \
- DEFINE_THREAD_MODEL \
+ DEFINE_THREAD_MODEL; \
} \
while (0)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 97bc211ff67..53e56bd4959 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -1375,7 +1375,7 @@ finish_co_return_stmt (location_t kw, tree expr)
/* Makes no sense for a co-routine really. */
if (TREE_THIS_VOLATILE (current_function_decl))
- warning_at (kw, 0,
+ warning_at (kw, OPT_Winvalid_noreturn_explicit,
"function declared %<noreturn%> has a"
" %<co_return%> statement");
diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 1b7a31d32f3..74cc59bfb87 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -11062,7 +11062,7 @@ check_return_expr (tree retval, bool *no_warning, bool
*dangling)
(This is a G++ extension, used to get better code for functions
that call the `volatile' function.) */
if (TREE_THIS_VOLATILE (current_function_decl))
- warning (0, "function declared %<noreturn%> has a %<return%> statement");
+ warning (OPT_Winvalid_noreturn_explicit, "function declared %<noreturn%> has a
%<return%> statement");
/* Check for various simple errors. */
if (DECL_DESTRUCTOR_P (current_function_decl))
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 2cba380718b..27d880fd4f0 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -376,6 +376,7 @@ Objective-C and Objective-C++ Dialects}.
-Winfinite-recursion
-Winit-self -Winline -Wno-int-conversion -Wint-in-bool-context
-Wno-int-to-pointer-cast -Wno-invalid-memory-model
+-Winvalid-noreturn=explicit -Winvalid-noreturn=implicit
-Winvalid-pch -Winvalid-utf8 -Wno-unicode -Wjump-misses-init
-Wlarger-than=@var{byte-size} -Wlogical-not-parentheses -Wlogical-op
-Wlong-long -Wno-lto-type-mismatch -Wmain -Wmaybe-uninitialized
@@ -10482,6 +10483,18 @@ an error. @option{Wint-to-pointer-cast} is enabled by
default.
Suppress warnings from casts from a pointer to an integer type of a
different size.
+@opindex Winvalid-noreturn=explicit
+@opindex Wno-invalid-noreturn=explicit
+@item -Winvalid-noreturn=explicit
+Warn if a function marked noreturn returns explicitly, that is, it
+contains a return statement.
+
+@opindex Winvalid-noreturn=implicit
+@opindex Wno-invalid-noreturn=implicit
+@item -Winvalid-noreturn=implicit
+Warn if a function marked noreturn returns implicitly, that is, it
+has a path in its control flow that can reach the end of its body.
+
@opindex Winvalid-pch
@opindex Wno-invalid-pch
@item -Winvalid-pch
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index 7fb7b92966b..cfe91038dd1 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -9817,7 +9817,7 @@ pass_warn_function_return::execute (function *fun)
}
if (location == UNKNOWN_LOCATION)
location = cfun->function_end_locus;
- warning_at (location, 0, "%<noreturn%> function does return");
+ warning_at (location, OPT_Winvalid_noreturn_implicit, "%<noreturn%> function
does return");
}
/* If we see "return;" in some basic block, then we do reach the end
