* Re: C PATCH to add -Wswitch-unreachable (PR c/49859)
[not found] ` <20160520163634.GN1611@redhat.com>
@ 2016-05-21 8:30 ` Bernhard Reutner-Fischer
2016-05-23 11:11 ` Marek Polacek
0 siblings, 1 reply; 2+ messages in thread
From: Bernhard Reutner-Fischer @ 2016-05-21 8:30 UTC (permalink / raw)
To: Marek Polacek; +Cc: gfortran
On May 20, 2016 6:36:34 PM GMT+02:00, Marek Polacek <polacek@redhat.com> wrote:
>On Thu, May 19, 2016 at 11:53:52AM -0400, Jason Merrill wrote:
>> Why implement this in the front end rather than at the gimple level?
>
>I was afraid that I wouldn't have as good a location info as in the FE
>and
>I wasn't sure if I'd be able to handle declarations well.
>
>Now that I've rewritten this to GIMPLE, I no longer fear so. Locations
>are
>ok for various gimple_assigns and I don't have to care about
>DECL_EXPRs.
>Moreover, this works fine even for the C++ FE now. (But I had to
>disable the
>warning for Fortran.)
Why did you have to disable it for Fortran? Worth a PR?
Can you elaborate, please?
thanks,
>
>I also discovered a bug in my previous version - it wouldn't warn for
> switch (i)
> {
> int i;
> int j = 10;
> case 4: ...
> }
>because it only looked at the first statement after switch (i) and
>punted
>for DECL_EXPRs. This now works as it should.
>
>Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
>2016-05-20 Marek Polacek <polacek@redhat.com>
>
> PR c/49859
> * c.opt (Wswitch-unreachable): New option.
>
> * doc/invoke.texi: Document -Wswitch-unreachable.
> * gimplify.c (gimplify_switch_expr): Implement the
>-Wswitch-unreachable
> warning.
>
> * c-c++-common/Wswitch-unreachable-1.c: New test.
> * gcc.dg/Wswitch-unreachable-1.c: New test.
> * c-c++-common/goacc/sb-2.c (void foo): Add dg-warning.
> * g++.dg/cpp0x/lambda/lambda-switch.C (main): Likewise.
> * g++.dg/gomp/block-10.C: Likewise.
> * gcc.dg/gomp/block-10.c: Likewise.
> * g++.dg/gomp/block-9.C: Likewise.
> * gcc.dg/gomp/block-9.c: Likewise.
> * g++.dg/gomp/target-1.C: Likewise.
> * g++.dg/gomp/target-2.C: Likewise.
> * gcc.dg/gomp/target-1.c: Likewise.
> * gcc.dg/gomp/target-2.c: Likewise.
> * g++.dg/gomp/taskgroup-1.C: Likewise.
> * gcc.dg/gomp/taskgroup-1.c: Likewise.
> * gcc.dg/gomp/teams-1.c: Likewise.
> * g++.dg/gomp/teams-1.C: Likewise.
> * g++.dg/overload/error3.C: Likewise.
> * g++.dg/tm/jump1.C: Likewise.
> * g++.dg/torture/pr40335.C: Likewise.
> * gcc.dg/c99-vla-jump-5.c: Likewise.
> * gcc.dg/switch-warn-1.c: Likewise.
> * gcc.dg/Wjump-misses-init-1.c: Use -Wno-switch-unreachable.
> * gcc.dg/nested-func-1.c: Likewise.
> * gcc.dg/pr67784-4.c: Likewise.
>
>diff --git gcc/c-family/c.opt gcc/c-family/c.opt
>index 918df16..ed98503 100644
>--- gcc/c-family/c.opt
>+++ gcc/c-family/c.opt
>@@ -634,6 +634,11 @@ Wswitch-bool
> C ObjC C++ ObjC++ Var(warn_switch_bool) Warning Init(1)
> Warn about switches with boolean controlling expression.
>
>+Wswitch-unreachable
>+C ObjC C++ ObjC++ Var(warn_switch_unreachable) Warning Init(1)
>+Warn about statements between switch's controlling expression and the
>first
>+case.
>+
> Wtemplates
> C++ ObjC++ Var(warn_templates) Warning
> Warn on primary template declaration.
>diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
>index f3d087f..5909b9d 100644
>--- gcc/doc/invoke.texi
>+++ gcc/doc/invoke.texi
>@@ -297,7 +297,8 @@ Objective-C and Objective-C++ Dialects}.
>-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]}
>@gol
>-Wsuggest-final-types @gol -Wsuggest-final-methods -Wsuggest-override
>@gol
> -Wmissing-format-attribute -Wsubobject-linkage @gol
>--Wswitch -Wswitch-default -Wswitch-enum -Wswitch-bool -Wsync-nand
>@gol
>+-Wswitch -Wswitch-default -Wswitch-enum -Wswitch-bool @gol
>+-Wswitch-unreachable -Wsync-nand @gol
>-Wsystem-headers -Wtautological-compare -Wtrampolines -Wtrigraphs
>@gol
> -Wtype-limits -Wundef @gol
> -Wuninitialized -Wunknown-pragmas -Wunsafe-loop-optimizations @gol
>@@ -4144,6 +4145,39 @@ switch ((int) (a == 4))
> @end smallexample
> This warning is enabled by default for C and C++ programs.
>
>+@item -Wswitch-unreachable
>+@opindex Wswitch-unreachable
>+@opindex Wno-switch-unreachable
>+Warn whenever a @code{switch} statement contains statements between
>the
>+controlling expression and the first case label, which will never be
>+executed. For example:
>+@smallexample
>+@group
>+switch (cond)
>+ @{
>+ i = 15;
>+ @dots{}
>+ case 5:
>+ @dots{}
>+ @}
>+@end group
>+@end smallexample
>+@option{-Wswitch-unreachable} will not warn if the statement between
>the
>+controlling expression and the first case label is just a declaration:
>+@smallexample
>+@group
>+switch (cond)
>+ @{
>+ int i;
>+ @dots{}
>+ case 5:
>+ i = 5;
>+ @dots{}
>+ @}
>+@end group
>+@end smallexample
>+This warning is enabled by default for C and C++ programs.
>+
> @item -Wsync-nand @r{(C and C++ only)}
> @opindex Wsync-nand
> @opindex Wno-sync-nand
>diff --git gcc/gimplify.c gcc/gimplify.c
>index c433a84..57eca85 100644
>--- gcc/gimplify.c
>+++ gcc/gimplify.c
>@@ -1595,6 +1595,32 @@ gimplify_switch_expr (tree *expr_p, gimple_seq
>*pre_p)
> gimplify_ctxp->case_labels.create (8);
>
> gimplify_stmt (&SWITCH_BODY (switch_expr), &switch_body_seq);
>+
>+ /* Possibly warn about unreachable statements between switch's
>+ controlling expression and the first case. */
>+ if (warn_switch_unreachable
>+ /* This warning doesn't play well with Fortran when optimizations
>+ are on. */
>+ && !lang_GNU_Fortran ()
>+ && switch_body_seq != NULL)
>+ {
>+ gimple_seq seq = switch_body_seq;
>+ if (gimple_code (switch_body_seq) == GIMPLE_BIND)
>+ seq = gimple_bind_body (as_a <gbind *> (switch_body_seq));
>+ gimple *stmt = gimple_seq_first_stmt (seq);
>+ enum gimple_code code = gimple_code (stmt);
>+ if (code != GIMPLE_LABEL && code != GIMPLE_TRY)
>+ {
>+ if (code == GIMPLE_GOTO
>+ && TREE_CODE (gimple_goto_dest (stmt)) == LABEL_DECL
>+ && DECL_ARTIFICIAL (gimple_goto_dest (stmt)))
>+ /* Don't warn for compiler-generated gotos. These occur
>+ in Duff's devices, for example. */;
>+ else
>+ warning_at (gimple_location (stmt), OPT_Wswitch_unreachable,
>+ "statement will never be executed");
>+ }
>+ }
> labels = gimplify_ctxp->case_labels;
> gimplify_ctxp->case_labels = saved_labels;
>
>diff --git gcc/testsuite/c-c++-common/Wswitch-unreachable-1.c
>gcc/testsuite/c-c++-common/Wswitch-unreachable-1.c
>index e69de29..ee6ecc1 100644
>--- gcc/testsuite/c-c++-common/Wswitch-unreachable-1.c
>+++ gcc/testsuite/c-c++-common/Wswitch-unreachable-1.c
>@@ -0,0 +1,116 @@
>+/* PR c/49859 */
>+/* { dg-do compile } */
>+
>+extern void foo (int);
>+extern int j;
>+
>+void
>+fn0 (int i)
>+{
>+ switch (i)
>+ {
>+ int k;
>+ case 1:
>+ k = 11;
>+ foo (k);
>+ }
>+
>+ switch (i)
>+ j = 10; /* { dg-warning "statement will never be executed" } */
>+
>+ switch (i)
>+ ;
>+
>+ switch (i)
>+ {
>+ j = 12; /* { dg-warning "statement will never be executed" } */
>+ default:
>+ foo (j);
>+ }
>+
>+ int o;
>+ switch (i)
>+ {
>+ o = 333; /* { dg-warning "statement will never be executed" } */
>+ case 4: break;
>+ default:
>+ foo (o);
>+ }
>+
>+ switch (i)
>+ switch (j) /* { dg-warning "statement will never be executed" } */
>+ {
>+ o = 42; /* { dg-warning "statement will never be executed" } */
>+ case 8:;
>+ }
>+
>+ switch (i)
>+ {
>+ int l = 3; /* { dg-warning "statement will never be executed" }
>*/
>+ o = 5;
>+ j = 7;
>+ ++l;
>+ }
>+
>+ switch (i)
>+ {
>+ int x;
>+ int l = 3; /* { dg-warning "statement will never be executed" }
>*/
>+ ++l, ++x;
>+ }
>+
>+ switch (i)
>+ if (j != 3) /* { dg-warning "statement will never be executed" }
>*/
>+ foo (j);
>+
>+ switch (i)
>+ while (1)
>+ foo (0);
>+
>+ switch (i)
>+ while (i > 5) { }
>+
>+ switch (i)
>+ goto X; /* { dg-warning "statement will never be executed" } */
>+X:
>+
>+ switch (i)
>+ do
>+ foo (1);
>+ while (1);
>+
>+ switch (i)
>+ for (;;)
>+ foo (-1);
>+
>+ switch (i)
>+ default:
>+ j = 6;
>+
>+ switch (i)
>+ {
>+ typedef int T;
>+ case 3:
>+ {
>+ T x = 5;
>+ foo (x);
>+ }
>+ }
>+
>+ switch (i)
>+ {
>+ static int g;
>+ default:
>+ foo (g);
>+ }
>+
>+ switch (i)
>+ {
>+L:
>+ j = 16;
>+ default:
>+ if (j < 5)
>+ goto L;
>+ break;
>+ }
>+}
>diff --git gcc/testsuite/c-c++-common/goacc/sb-2.c
>gcc/testsuite/c-c++-common/goacc/sb-2.c
>index a6760ec..e986af3 100644
>--- gcc/testsuite/c-c++-common/goacc/sb-2.c
>+++ gcc/testsuite/c-c++-common/goacc/sb-2.c
>@@ -4,19 +4,19 @@ void foo(int i)
> {
> switch (i) // { dg-error "invalid entry to OpenACC structured block" }
> {
>- #pragma acc parallel
>+ #pragma acc parallel // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> }
>
> switch (i) // { dg-error "invalid entry to OpenACC structured block" }
> {
>- #pragma acc kernels
>+ #pragma acc kernels // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> }
>
> switch (i) // { dg-error "invalid entry to OpenACC structured block" }
> {
>- #pragma acc data
>+ #pragma acc data // { dg-warning "statement will never be executed"
>}
> { case 0:; }
> }
> }
>diff --git gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch.C
>gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch.C
>index 1cac211..d71d3ad 100644
>--- gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch.C
>+++ gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch.C
>@@ -20,7 +20,7 @@ main ()
> {
> case 3: // { dg-error "case" }
> break; // { dg-error "break" }
>- };
>+ }; // { dg-warning "statement will never be executed" }
> }
> }
> }
>diff --git gcc/testsuite/g++.dg/gomp/block-10.C
>gcc/testsuite/g++.dg/gomp/block-10.C
>index b273c1f..4aa41cd 100644
>--- gcc/testsuite/g++.dg/gomp/block-10.C
>+++ gcc/testsuite/g++.dg/gomp/block-10.C
>@@ -5,28 +5,28 @@ void foo(int i)
> int j;
> switch (i)
> {
>- #pragma omp parallel
>+ #pragma omp parallel // { dg-warning "statement will never be
>executed" }
> { case 0:; } // { dg-error "jump|enters" }
> }
> switch (i)
> {
>- #pragma omp for
>+ #pragma omp for // { dg-warning "statement will never be executed" }
> for (j = 0; j < 10; ++ j)
> { case 1:; } // { dg-error "jump|enters" }
> }
> switch (i)
> {
>- #pragma omp critical
>+ #pragma omp critical // { dg-warning "statement will never be
>executed" }
> { case 2:; } // { dg-error "jump|enters" }
> }
> switch (i)
> {
>- #pragma omp master
>+ #pragma omp master // { dg-warning "statement will never be
>executed" }
> { case 3:; } // { dg-error "jump|enters" }
> }
> switch (i)
> {
>- #pragma omp sections
>+ #pragma omp sections // { dg-warning "statement will never be
>executed" }
> { case 4:; // { dg-error "jump|enters" }
> #pragma omp section
> { case 5:; } // { dg-error "jump|enters" }
>@@ -34,7 +34,7 @@ void foo(int i)
> }
> switch (i)
> {
>- #pragma omp ordered
>+ #pragma omp ordered // { dg-warning "statement will never be
>executed" }
> { default:; } // { dg-error "jump|enters" }
> }
> }
>diff --git gcc/testsuite/g++.dg/gomp/block-9.C
>gcc/testsuite/g++.dg/gomp/block-9.C
>index 8012e5a..1de40a9 100644
>--- gcc/testsuite/g++.dg/gomp/block-9.C
>+++ gcc/testsuite/g++.dg/gomp/block-9.C
>@@ -5,7 +5,7 @@ void foo(int i)
> int j;
> switch (i)
> {
>- #pragma omp parallel
>+ #pragma omp parallel // { dg-warning "statement will never be
>executed" }
> { case 0:; } // { dg-error "jump|enters" }
> #pragma omp for
> for (j = 0; j < 10; ++ j)
>diff --git gcc/testsuite/g++.dg/gomp/target-1.C
>gcc/testsuite/g++.dg/gomp/target-1.C
>index bcdac61..9750873 100644
>--- gcc/testsuite/g++.dg/gomp/target-1.C
>+++ gcc/testsuite/g++.dg/gomp/target-1.C
>@@ -24,7 +24,7 @@ foo (int x)
>
> switch (x)
> {
>- #pragma omp target
>+ #pragma omp target // { dg-warning "statement will never be
>executed" }
> { case 0:; } // { dg-error "jump" }
> // { dg-message "enters" "" { target *-*-* } 28 }
> }
>diff --git gcc/testsuite/g++.dg/gomp/target-2.C
>gcc/testsuite/g++.dg/gomp/target-2.C
>index 273f8d5..333b4d0 100644
>--- gcc/testsuite/g++.dg/gomp/target-2.C
>+++ gcc/testsuite/g++.dg/gomp/target-2.C
>@@ -24,7 +24,7 @@ foo (int x, int y)
>
> switch (x)
> {
>- #pragma omp target data map(tofrom: y)
>+ #pragma omp target data map(tofrom: y) // { dg-warning "statement
>will never be executed" }
> { case 0:; } // { dg-error "jump" }
> // { dg-message "enters" "" { target *-*-* } 28 }
> }
>diff --git gcc/testsuite/g++.dg/gomp/taskgroup-1.C
>gcc/testsuite/g++.dg/gomp/taskgroup-1.C
>index e15d59d..5542a4e 100644
>--- gcc/testsuite/g++.dg/gomp/taskgroup-1.C
>+++ gcc/testsuite/g++.dg/gomp/taskgroup-1.C
>@@ -24,7 +24,7 @@ foo (int x)
>
> switch (x)
> {
>- #pragma omp taskgroup
>+ #pragma omp taskgroup // { dg-warning "statement will never be
>executed" }
> { case 0:; } // { dg-error "jump" }
> // { dg-message "enters" "" { target *-*-* } 28 }
> }
>diff --git gcc/testsuite/g++.dg/gomp/teams-1.C
>gcc/testsuite/g++.dg/gomp/teams-1.C
>index 2b00bb6..d0460c3 100644
>--- gcc/testsuite/g++.dg/gomp/teams-1.C
>+++ gcc/testsuite/g++.dg/gomp/teams-1.C
>@@ -26,6 +26,7 @@ foo (int x)
> {
> #pragma omp target teams
> { case 0:; } // { dg-error "jump" }
>+ // { dg-warning "statement will never be executed" "" { target
>*-*-* } 28 }
> // { dg-message "enters" "" { target *-*-* } 28 }
> }
> }
>@@ -43,7 +44,7 @@ bar (int x)
> #pragma omp teams
> {
> bad2: ; // { dg-error "jump to label" }
>- // { dg-message "enters OpenMP" "" {
>target *-*-* } 45 }
>+ // { dg-message "enters OpenMP" "" {
>target *-*-* } 46 }
> }
>
> #pragma omp target
>@@ -57,14 +58,14 @@ bar (int x)
>
> switch (x)
> {
>- #pragma omp target
>+ #pragma omp target // { dg-warning "statement will never be
>executed" }
> #pragma omp teams
> { case 0:; } // { dg-error "jump" }
>- // { dg-message "enters" "" { target
>*-*-* } 62 }
>+ // { dg-message "enters" "" { target
>*-*-* } 63 }
> }
> }
>
>// { dg-error "invalid branch to/from OpenMP structured block" "" {
>target *-*-* } 8 }
>// { dg-error "invalid entry to OpenMP structured block" "" { target
>*-*-* } 10 }
>-// { dg-error "invalid branch to/from OpenMP structured block" "" {
>target *-*-* } 39 }
>-// { dg-error "invalid entry to OpenMP structured block" "" { target
>*-*-* } 41 }
>+// { dg-error "invalid branch to/from OpenMP structured block" "" {
>target *-*-* } 40 }
>+// { dg-error "invalid entry to OpenMP structured block" "" { target
>*-*-* } 42 }
>diff --git gcc/testsuite/g++.dg/overload/error3.C
>gcc/testsuite/g++.dg/overload/error3.C
>index e0003dd..8391875 100644
>--- gcc/testsuite/g++.dg/overload/error3.C
>+++ gcc/testsuite/g++.dg/overload/error3.C
>@@ -35,6 +35,7 @@ class MainWindow {
> void MainWindow::update_status(Result result) {
> switch (result) {
>status_frame.modify_bg(Gtk::STATE_NORMAL,Gdk::Color::Color("green"));
>// { dg-error "" }
>+ // { dg-warning "statement will never be executed" "" { target *-*-*
>} 37 }
>status_frame.modify_bg(Gtk::STATE_NORMAL,Gdk::Color::Color("red")); //
>{ dg-error "" }
> status_label.set_text("Out of memory");
> }
>diff --git gcc/testsuite/g++.dg/tm/jump1.C
>gcc/testsuite/g++.dg/tm/jump1.C
>index 003eed0..e28282d 100644
>--- gcc/testsuite/g++.dg/tm/jump1.C
>+++ gcc/testsuite/g++.dg/tm/jump1.C
>@@ -14,7 +14,7 @@ void f()
>
> switch (i)
> {
>- synchronized {
>+ synchronized { // { dg-warning "statement will never be
>executed" }
> ++i;
> case 42: // { dg-error "" }
> ++i;
>diff --git gcc/testsuite/g++.dg/torture/pr40335.C
>gcc/testsuite/g++.dg/torture/pr40335.C
>index 14ea95d..295a356 100644
>--- gcc/testsuite/g++.dg/torture/pr40335.C
>+++ gcc/testsuite/g++.dg/torture/pr40335.C
>@@ -8,7 +8,7 @@ main (void)
> switch ((signed char) i)
> {
>case 255: /* { dg-bogus "exceeds maximum value" "" { xfail *-*-* } } */
>- abort ();
>+ abort (); /* { dg-warning "statement will never be executed" } */
> default:
> break;
> }
>diff --git gcc/testsuite/gcc.dg/Wjump-misses-init-1.c
>gcc/testsuite/gcc.dg/Wjump-misses-init-1.c
>index 86117f1..71809be 100644
>--- gcc/testsuite/gcc.dg/Wjump-misses-init-1.c
>+++ gcc/testsuite/gcc.dg/Wjump-misses-init-1.c
>@@ -1,5 +1,5 @@
> /* { dg-do compile } */
>-/* { dg-options "-Wjump-misses-init" } */
>+/* { dg-options "-Wjump-misses-init -Wno-switch-unreachable" } */
> int
> f1 (int a)
> {
>diff --git gcc/testsuite/gcc.dg/Wswitch-unreachable-1.c
>gcc/testsuite/gcc.dg/Wswitch-unreachable-1.c
>index e69de29..2e5c99b 100644
>--- gcc/testsuite/gcc.dg/Wswitch-unreachable-1.c
>+++ gcc/testsuite/gcc.dg/Wswitch-unreachable-1.c
>@@ -0,0 +1,35 @@
>+/* PR c/49859 */
>+/* { dg-do compile } */
>+/* { dg-options "-Wswitch-unreachable" } */
>+
>+extern void foo (int);
>+extern int j;
>+
>+void
>+fn0 (int i)
>+{
>+ switch (i)
>+ {
>+ int t = 10; /* { dg-warning "statement will never be executed" }
>*/
>+ default:
>+ foo (t);
>+ }
>+
>+ switch (i)
>+ { /* { dg-warning "statement will never be executed" } */
>+ int A[i];
>+ default: /* { dg-error "switch jumps into scope" } */
>+ break;
>+ }
>+
>+ switch (i)
>+ default:
>+ j = sizeof (struct { int i; });
>+
>+ switch (i)
>+ {
>+ int A[3];
>+ default:
>+ break;
>+ }
>+}
>diff --git gcc/testsuite/gcc.dg/c99-vla-jump-5.c
>gcc/testsuite/gcc.dg/c99-vla-jump-5.c
>index fc5e04d..5b5fc74 100644
>--- gcc/testsuite/gcc.dg/c99-vla-jump-5.c
>+++ gcc/testsuite/gcc.dg/c99-vla-jump-5.c
>@@ -14,7 +14,7 @@
> void
> f (int a, int b)
> {
>- switch (a) {
>+ switch (a) { /* { dg-warning "statement will never be executed" } */
> int v[b];
>case 2: /* { dg-error "switch jumps into scope of identifier with
>variably modified type" } */
>default: /* { dg-error "switch jumps into scope of identifier with
>variably modified type" } */
>diff --git gcc/testsuite/gcc.dg/gomp/block-10.c
>gcc/testsuite/gcc.dg/gomp/block-10.c
>index 69ae3c0..29c2d91 100644
>--- gcc/testsuite/gcc.dg/gomp/block-10.c
>+++ gcc/testsuite/gcc.dg/gomp/block-10.c
>@@ -5,28 +5,28 @@ void foo(int i)
> int j;
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp parallel
>+ #pragma omp parallel // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> }
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp for
>+ #pragma omp for // { dg-warning "statement will never be executed" }
> for (j = 0; j < 10; ++ j)
> { case 1:; }
> }
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp critical
>+ #pragma omp critical // { dg-warning "statement will never be
>executed" }
> { case 2:; }
> }
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp master
>+ #pragma omp master // { dg-warning "statement will never be
>executed" }
> { case 3:; }
> }
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp sections
>+ #pragma omp sections // { dg-warning "statement will never be
>executed" }
> { case 4:;
> #pragma omp section
> { case 5:; }
>@@ -34,7 +34,7 @@ void foo(int i)
> }
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp ordered
>+ #pragma omp ordered // { dg-warning "statement will never be
>executed" }
> { default:; }
> }
> }
>diff --git gcc/testsuite/gcc.dg/gomp/block-9.c
>gcc/testsuite/gcc.dg/gomp/block-9.c
>index 2fae3de..202599f 100644
>--- gcc/testsuite/gcc.dg/gomp/block-9.c
>+++ gcc/testsuite/gcc.dg/gomp/block-9.c
>@@ -5,7 +5,7 @@ void foo(int i)
> int j;
> switch (i) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp parallel
>+ #pragma omp parallel // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> #pragma omp for
> for (j = 0; j < 10; ++ j)
>diff --git gcc/testsuite/gcc.dg/gomp/target-1.c
>gcc/testsuite/gcc.dg/gomp/target-1.c
>index aaa6a14..6bc5eb9 100644
>--- gcc/testsuite/gcc.dg/gomp/target-1.c
>+++ gcc/testsuite/gcc.dg/gomp/target-1.c
>@@ -23,7 +23,7 @@ foo (int x)
>
> switch (x) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp target
>+ #pragma omp target // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> }
> }
>diff --git gcc/testsuite/gcc.dg/gomp/target-2.c
>gcc/testsuite/gcc.dg/gomp/target-2.c
>index 3a7afc4..c5c38d8 100644
>--- gcc/testsuite/gcc.dg/gomp/target-2.c
>+++ gcc/testsuite/gcc.dg/gomp/target-2.c
>@@ -23,7 +23,7 @@ foo (int x, int y)
>
> switch (x) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp target data map(tofrom: y)
>+ #pragma omp target data map(tofrom: y) // { dg-warning "statement
>will never be executed" }
> { case 0:; }
> }
> }
>diff --git gcc/testsuite/gcc.dg/gomp/taskgroup-1.c
>gcc/testsuite/gcc.dg/gomp/taskgroup-1.c
>index 1997e0c..f39b7ef 100644
>--- gcc/testsuite/gcc.dg/gomp/taskgroup-1.c
>+++ gcc/testsuite/gcc.dg/gomp/taskgroup-1.c
>@@ -23,7 +23,7 @@ foo (int x)
>
> switch (x) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp taskgroup
>+ #pragma omp taskgroup // { dg-warning "statement will never be
>executed" }
> { case 0:; }
> }
> }
>diff --git gcc/testsuite/gcc.dg/gomp/teams-1.c
>gcc/testsuite/gcc.dg/gomp/teams-1.c
>index ad5b100..a537047 100644
>--- gcc/testsuite/gcc.dg/gomp/teams-1.c
>+++ gcc/testsuite/gcc.dg/gomp/teams-1.c
>@@ -24,7 +24,7 @@ foo (int x)
> switch (x) // { dg-error "invalid entry to OpenMP structured block" }
> {
> #pragma omp target teams
>- { case 0:; }
>+ { case 0:; } // { dg-warning "statement will never be executed" }
> }
> }
>
>@@ -54,7 +54,7 @@ bar (int x)
>
> switch (x) // { dg-error "invalid entry to OpenMP structured block" }
> {
>- #pragma omp target
>+ #pragma omp target // { dg-warning "statement will never be
>executed" }
> #pragma omp teams
> { case 0:; }
> }
>diff --git gcc/testsuite/gcc.dg/nested-func-1.c
>gcc/testsuite/gcc.dg/nested-func-1.c
>index cb26e89..2052a6f 100644
>--- gcc/testsuite/gcc.dg/nested-func-1.c
>+++ gcc/testsuite/gcc.dg/nested-func-1.c
>@@ -1,7 +1,7 @@
>/* Test for proper errors for break and continue in nested functions.
>*/
> /* Origin: Joseph Myers <jsm@polyomino.org.uk> */
> /* { dg-do compile } */
>-/* { dg-options "" } */
>+/* { dg-options "-Wno-switch-unreachable" } */
>
> void
> foo (int a)
>diff --git gcc/testsuite/gcc.dg/pr67784-4.c
>gcc/testsuite/gcc.dg/pr67784-4.c
>index 81a43fd..5462080 100644
>--- gcc/testsuite/gcc.dg/pr67784-4.c
>+++ gcc/testsuite/gcc.dg/pr67784-4.c
>@@ -1,6 +1,6 @@
> /* PR c/67784 */
> /* { dg-do compile } */
>-/* { dg-options "" } */
>+/* { dg-options "-Wno-switch-unreachable" } */
>
> typedef int T;
>
>diff --git gcc/testsuite/gcc.dg/switch-warn-1.c
>gcc/testsuite/gcc.dg/switch-warn-1.c
>index 04ca4e3..58fbd7d 100644
>--- gcc/testsuite/gcc.dg/switch-warn-1.c
>+++ gcc/testsuite/gcc.dg/switch-warn-1.c
>@@ -11,7 +11,7 @@ foo1 (unsigned char i)
> {
> switch (i)
> {
>- case -1: /* { dg-warning "case label value is less than minimum
>value for type" } */
>+ case -1: /* { dg-warning "case label value is less than minimum
>value for type|statement will never be executed" } */
> return 1;
>case 256: /* { dg-warning "case label value exceeds maximum value for
>type" } */
> return 2;
>
> Marek
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: C PATCH to add -Wswitch-unreachable (PR c/49859)
2016-05-21 8:30 ` C PATCH to add -Wswitch-unreachable (PR c/49859) Bernhard Reutner-Fischer
@ 2016-05-23 11:11 ` Marek Polacek
0 siblings, 0 replies; 2+ messages in thread
From: Marek Polacek @ 2016-05-23 11:11 UTC (permalink / raw)
To: Bernhard Reutner-Fischer; +Cc: gfortran
On Sat, May 21, 2016 at 10:28:26AM +0200, Bernhard Reutner-Fischer wrote:
> On May 20, 2016 6:36:34 PM GMT+02:00, Marek Polacek <polacek@redhat.com> wrote:
> >On Thu, May 19, 2016 at 11:53:52AM -0400, Jason Merrill wrote:
> >> Why implement this in the front end rather than at the gimple level?
> >
> >I was afraid that I wouldn't have as good a location info as in the FE
> >and
> >I wasn't sure if I'd be able to handle declarations well.
> >
> >Now that I've rewritten this to GIMPLE, I no longer fear so. Locations
> >are
> >ok for various gimple_assigns and I don't have to care about
> >DECL_EXPRs.
> >Moreover, this works fine even for the C++ FE now. (But I had to
> >disable the
> >warning for Fortran.)
>
> Why did you have to disable it for Fortran? Worth a PR?
> Can you elaborate, please?
The problem was with testsuite/gfortran.dg/select_char_2.f90: there we have
select case (c)
case ('ea':'ez')
bar = 2
case ('e')
bar = 1
case default
bar = 3
case ('fd')
bar = 4
end select
and with -O the first case seems to be optimized away so the warning triggered.
This optimization didn't happen with optimizations turned off.
I don't know whether the warning makes sense for Fortran nor do I know if this
is worth a PR. Someone more knowledgeable about Fortran would have to decide.
That's why I disabled the warning for Fortran. It can be improved/adjusted
down the line, of course.
Marek
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2016-05-23 11:11 UTC | newest]
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2016-05-21 8:30 ` C PATCH to add -Wswitch-unreachable (PR c/49859) Bernhard Reutner-Fischer
2016-05-23 11:11 ` Marek Polacek
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