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Re: C/C++ PATCH to smarten up -Wswitch-bool (PR c/66322)
- From: Marek Polacek <polacek at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Joseph Myers <joseph at codesourcery dot com>, Jason Merrill <jason at redhat dot com>
- Date: Thu, 25 Jun 2015 14:46:11 +0200
- Subject: Re: C/C++ PATCH to smarten up -Wswitch-bool (PR c/66322)
- Authentication-results: sourceware.org; auth=none
- References: <20150610180201 dot GW2756 at redhat dot com> <20150618115034 dot GB10139 at redhat dot com>
Ping.
On Thu, Jun 18, 2015 at 01:50:34PM +0200, Marek Polacek wrote:
> Ping.
>
> On Wed, Jun 10, 2015 at 08:02:01PM +0200, Marek Polacek wrote:
> > Linus's kind words here <https://lkml.org/lkml/2015/5/27/941> prodded
> > me to improving the -Wswitch-bool warning. In particular, this patch
> > makes the warning not warn when the case values aren't outside bool
> > range. But it will still warn about
> >
> > switch (boolean)
> > {
> > case false ... true: ...
> > default: ...
> > }
> >
> > That of course means that the warning must be delayed to the point where
> > all the case labels have been parsed. Then there are these annoying
> > differences between C and C++ (type of a comparison), which means some
> > splay trees fun. Another problem stems from the fact that case labels
> > that are outside the range of the original type of the switch controlling
> > expression are dropped on the floor, so I had to add the OUTSIDE_RANGE_P
> > flag. Case ranges are fun as well.
> >
> > If this patch is approved, I'd like to backport it even to 5 branch after
> > some time so it's fixed in 5.2.
> >
> > There's also the possibility to add -Wswitch-bool=2 that would warn every
> > time the compiler sees a switch with a boolean controlling expr, i.e. do
> > what we're doing now. But that would be something for trunk only.
> >
> > Thoughts?
> >
> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> >
> > 2015-06-10 Marek Polacek <polacek@redhat.com>
> >
> > PR c/66322
> > * c-common.c (check_case_bounds): Add bool * parameter. Set
> > OUTSIDE_RANGE_P.
> > (c_add_case_label): Add bool * parameter. Pass it down to
> > check_case_bounds.
> > (c_do_switch_warnings): Add bool parameters. Implement -Wswitch-bool
> > warning here.
> > * c-common.h (c_add_case_label, c_do_switch_warnings): Update
> > declarations.
> >
> > * c-typeck.c (struct c_switch): Add BOOL_COND_P and OUTSIDE_RANGE_P.
> > (c_start_case): Set BOOL_COND_P and OUTSIDE_RANGE_P. Don't warn
> > about -Wswitch-bool here.
> > (do_case): Update c_add_case_label call.
> > (c_finish_case): Update c_do_switch_warnings call.
> >
> > * decl.c (struct cp_switch): Add OUTSIDE_RANGE_P.
> > (push_switch): Set OUTSIDE_RANGE_P.
> > (pop_switch): Update c_do_switch_warnings call.
> > (finish_case_label): Update c_add_case_label call.
> > * semantics.c (finish_switch_cond): Don't warn about -Wswitch-bool
> > here.
> >
> > * function.c (stack_protect_epilogue): Remove a cast to int.
> > * doc/invoke.texi: Update -Wswitch-bool description.
> >
> > * c-c++-common/pr60439.c: Add dg-prune-output and add switch cases.
> > * c-c++-common/pr66322.c: New test.
> > * g++.dg/eh/scope1.C: Remove dg-warning.
> >
> > diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
> > index 5903c75..3746de7 100644
> > --- gcc/doc/invoke.texi
> > +++ gcc/doc/invoke.texi
> > @@ -4012,7 +4012,8 @@ warning about an omitted enumeration code even if there is a
> > @item -Wswitch-bool
> > @opindex Wswitch-bool
> > @opindex Wno-switch-bool
> > -Warn whenever a @code{switch} statement has an index of boolean type.
> > +Warn whenever a @code{switch} statement has an index of boolean type
> > +and the case values are outside the range of a boolean type.
> > It is possible to suppress this warning by casting the controlling
> > expression to a type other than @code{bool}. For example:
> > @smallexample
> > diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
> > index 5b76567..6f9f056 100644
> > --- gcc/c-family/c-common.c
> > +++ gcc/c-family/c-common.c
> > @@ -312,7 +312,8 @@ struct visibility_flags visibility_options;
> >
> > static tree c_fully_fold_internal (tree expr, bool, bool *, bool *, bool);
> > static tree check_case_value (location_t, tree);
> > -static bool check_case_bounds (location_t, tree, tree, tree *, tree *);
> > +static bool check_case_bounds (location_t, tree, tree, tree *, tree *,
> > + bool *);
> >
> > static tree handle_packed_attribute (tree *, tree, tree, int, bool *);
> > static tree handle_nocommon_attribute (tree *, tree, tree, int, bool *);
> > @@ -3639,13 +3640,15 @@ check_case_value (location_t loc, tree value)
> > bound of the case label, and CASE_HIGH_P is the upper bound or NULL
> > if the case is not a case range.
> > The caller has to make sure that we are not called with NULL for
> > - CASE_LOW_P (i.e. the default case).
> > + CASE_LOW_P (i.e. the default case). OUTSIDE_RANGE_P says whether there
> > + was a case value that doesn't fit into the range of the ORIG_TYPE.
> > Returns true if the case label is in range of ORIG_TYPE (saturated or
> > untouched) or false if the label is out of range. */
> >
> > static bool
> > check_case_bounds (location_t loc, tree type, tree orig_type,
> > - tree *case_low_p, tree *case_high_p)
> > + tree *case_low_p, tree *case_high_p,
> > + bool *outside_range_p)
> > {
> > tree min_value, max_value;
> > tree case_low = *case_low_p;
> > @@ -3664,6 +3667,7 @@ check_case_bounds (location_t loc, tree type, tree orig_type,
> > {
> > warning_at (loc, 0, "case label value is less than minimum value "
> > "for type");
> > + *outside_range_p = true;
> > return false;
> > }
> >
> > @@ -3672,6 +3676,7 @@ check_case_bounds (location_t loc, tree type, tree orig_type,
> > && tree_int_cst_compare (case_high, max_value) > 0)
> > {
> > warning_at (loc, 0, "case label value exceeds maximum value for type");
> > + *outside_range_p = true;
> > return false;
> > }
> >
> > @@ -3681,6 +3686,7 @@ check_case_bounds (location_t loc, tree type, tree orig_type,
> > {
> > warning_at (loc, 0, "lower value in case label range"
> > " less than minimum value for type");
> > + *outside_range_p = true;
> > case_low = min_value;
> > }
> >
> > @@ -3690,6 +3696,7 @@ check_case_bounds (location_t loc, tree type, tree orig_type,
> > {
> > warning_at (loc, 0, "upper value in case label range"
> > " exceeds maximum value for type");
> > + *outside_range_p = true;
> > case_high = max_value;
> > }
> >
> > @@ -6383,13 +6390,14 @@ case_compare (splay_tree_key k1, splay_tree_key k2)
> > HIGH_VALUE is NULL_TREE, then case label was declared using the
> > usual C/C++ syntax, rather than the GNU case range extension.
> > CASES is a tree containing all the case ranges processed so far;
> > - COND is the condition for the switch-statement itself. Returns the
> > - CASE_LABEL_EXPR created, or ERROR_MARK_NODE if no CASE_LABEL_EXPR
> > - is created. */
> > + COND is the condition for the switch-statement itself.
> > + OUTSIDE_RANGE_P says whether there was a case value that doesn't
> > + fit into the range of the ORIG_TYPE. Returns the CASE_LABEL_EXPR
> > + created, or ERROR_MARK_NODE if no CASE_LABEL_EXPR is created. */
> >
> > tree
> > c_add_case_label (location_t loc, splay_tree cases, tree cond, tree orig_type,
> > - tree low_value, tree high_value)
> > + tree low_value, tree high_value, bool *outside_range_p)
> > {
> > tree type;
> > tree label;
> > @@ -6450,7 +6458,8 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond, tree orig_type,
> > don't insert the case label and return NULL_TREE. */
> > if (low_value
> > && !check_case_bounds (loc, type, orig_type,
> > - &low_value, high_value ? &high_value : NULL))
> > + &low_value, high_value ? &high_value : NULL,
> > + outside_range_p))
> > return NULL_TREE;
> >
> > /* Look up the LOW_VALUE in the table of case labels we already
> > @@ -6611,13 +6620,15 @@ match_case_to_enum (splay_tree_node node, void *data)
> >
> > void
> > c_do_switch_warnings (splay_tree cases, location_t switch_location,
> > - tree type, tree cond)
> > + tree type, tree cond, bool bool_cond_p,
> > + bool outside_range_p)
> > {
> > splay_tree_node default_node;
> > splay_tree_node node;
> > tree chain;
> >
> > - if (!warn_switch && !warn_switch_enum && !warn_switch_default)
> > + if (!warn_switch && !warn_switch_enum && !warn_switch_default
> > + && !warn_switch_bool)
> > return;
> >
> > default_node = splay_tree_lookup (cases, (splay_tree_key) NULL);
> > @@ -6625,6 +6636,52 @@ c_do_switch_warnings (splay_tree cases, location_t switch_location,
> > warning_at (switch_location, OPT_Wswitch_default,
> > "switch missing default case");
> >
> > + /* There are certain cases where -Wswitch-bool warnings aren't
> > + desirable, such as
> > + switch (boolean)
> > + {
> > + case true: ...
> > + case false: ...
> > + }
> > + so be careful here. */
> > + if (warn_switch_bool && bool_cond_p)
> > + {
> > + splay_tree_node min_node;
> > + /* If there's a default node, it's also the value with the minimal
> > + key. So look at the penultimate key (if any). */
> > + if (default_node)
> > + min_node = splay_tree_successor (cases, (splay_tree_key) NULL);
> > + else
> > + min_node = splay_tree_min (cases);
> > + tree min = min_node ? (tree) min_node->key : NULL_TREE;
> > +
> > + splay_tree_node max_node = splay_tree_max (cases);
> > + /* This might be a case range, so look at the value with the
> > + maximal key and then check CASE_HIGH. */
> > + tree max = max_node ? (tree) max_node->value : NULL_TREE;
> > + if (max)
> > + max = CASE_HIGH (max) ? CASE_HIGH (max) : CASE_LOW (max);
> > +
> > + /* If there's a case value > 1 or < 0, that is outside bool
> > + range, warn. */
> > + if (outside_range_p
> > + || (max && wi::gts_p (max, 1))
> > + || (min && wi::lts_p (min, 0))
> > + /* And handle the
> > + switch (boolean)
> > + {
> > + case true: ...
> > + case false: ...
> > + default: ...
> > + }
> > + case, where we want to warn. */
> > + || (default_node
> > + && max && wi::eq_p (max, 1)
> > + && min && wi::eq_p (min, 0)))
> > + warning_at (switch_location, OPT_Wswitch_bool,
> > + "switch condition has boolean value");
> > + }
> > +
> > /* From here on, we only care about about enumerated types. */
> > if (!type || TREE_CODE (type) != ENUMERAL_TYPE)
> > return;
> > diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
> > index 7ba81c4..3578929 100644
> > --- gcc/c-family/c-common.h
> > +++ gcc/c-family/c-common.h
> > @@ -947,9 +947,11 @@ extern tree boolean_increment (enum tree_code, tree);
> >
> > extern int case_compare (splay_tree_key, splay_tree_key);
> >
> > -extern tree c_add_case_label (location_t, splay_tree, tree, tree, tree, tree);
> > +extern tree c_add_case_label (location_t, splay_tree, tree, tree, tree, tree,
> > + bool *);
> >
> > -extern void c_do_switch_warnings (splay_tree, location_t, tree, tree);
> > +extern void c_do_switch_warnings (splay_tree, location_t, tree, tree, bool,
> > + bool);
> >
> > extern tree build_function_call (location_t, tree, tree);
> >
> > diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
> > index 636e0bb..04a50c7 100644
> > --- gcc/c/c-typeck.c
> > +++ gcc/c/c-typeck.c
> > @@ -9529,6 +9529,14 @@ struct c_switch {
> >
> > /* The next node on the stack. */
> > struct c_switch *next;
> > +
> > + /* Remember whether the controlling expression had boolean type
> > + before integer promotions for the sake of -Wswitch-bool. */
> > + bool bool_cond_p;
> > +
> > + /* Remember whether there was a case value that is outside the
> > + range of the ORIG_TYPE. */
> > + bool outside_range_p;
> > };
> >
> > /* A stack of the currently active switch statements. The innermost
> > @@ -9542,7 +9550,7 @@ struct c_switch *c_switch_stack;
> > /* Start a C switch statement, testing expression EXP. Return the new
> > SWITCH_EXPR. SWITCH_LOC is the location of the `switch'.
> > SWITCH_COND_LOC is the location of the switch's condition.
> > - EXPLICIT_CAST_P is true if the expression EXP has explicit cast. */
> > + EXPLICIT_CAST_P is true if the expression EXP has an explicit cast. */
> >
> > tree
> > c_start_case (location_t switch_loc,
> > @@ -9550,6 +9558,7 @@ c_start_case (location_t switch_loc,
> > tree exp, bool explicit_cast_p)
> > {
> > tree orig_type = error_mark_node;
> > + bool bool_cond_p = false;
> > struct c_switch *cs;
> >
> > if (exp != error_mark_node)
> > @@ -9579,8 +9588,7 @@ c_start_case (location_t switch_loc,
> > /* Explicit cast to int suppresses this warning. */
> > && !(TREE_CODE (type) == INTEGER_TYPE
> > && explicit_cast_p))
> > - warning_at (switch_cond_loc, OPT_Wswitch_bool,
> > - "switch condition has boolean value");
> > + bool_cond_p = true;
> >
> > if (!in_system_header_at (input_location)
> > && (type == long_integer_type_node
> > @@ -9604,6 +9612,8 @@ c_start_case (location_t switch_loc,
> > cs->orig_type = orig_type;
> > cs->cases = splay_tree_new (case_compare, NULL, NULL);
> > cs->bindings = c_get_switch_bindings ();
> > + cs->bool_cond_p = bool_cond_p;
> > + cs->outside_range_p = false;
> > cs->next = c_switch_stack;
> > c_switch_stack = cs;
> >
> > @@ -9650,7 +9660,8 @@ do_case (location_t loc, tree low_value, tree high_value)
> > label = c_add_case_label (loc, c_switch_stack->cases,
> > SWITCH_COND (c_switch_stack->switch_expr),
> > c_switch_stack->orig_type,
> > - low_value, high_value);
> > + low_value, high_value,
> > + &c_switch_stack->outside_range_p);
> > if (label == error_mark_node)
> > label = NULL_TREE;
> > return label;
> > @@ -9671,7 +9682,8 @@ c_finish_case (tree body, tree type)
> > switch_location = EXPR_LOCATION (cs->switch_expr);
> > c_do_switch_warnings (cs->cases, switch_location,
> > type ? type : TREE_TYPE (cs->switch_expr),
> > - SWITCH_COND (cs->switch_expr));
> > + SWITCH_COND (cs->switch_expr),
> > + cs->bool_cond_p, cs->outside_range_p);
> >
> > /* Pop the stack. */
> > c_switch_stack = cs->next;
> > diff --git gcc/cp/decl.c gcc/cp/decl.c
> > index 3bed538..c7b27ff 100644
> > --- gcc/cp/decl.c
> > +++ gcc/cp/decl.c
> > @@ -3212,6 +3212,9 @@ struct cp_switch
> > label. We need a tree, rather than simply a hash table, because
> > of the GNU case range extension. */
> > splay_tree cases;
> > + /* Remember whether there was a case value that is outside the
> > + range of the original type of the controlling expression. */
> > + bool outside_range_p;
> > };
> >
> > /* A stack of the currently active switch statements. The innermost
> > @@ -3233,6 +3236,7 @@ push_switch (tree switch_stmt)
> > p->next = switch_stack;
> > p->switch_stmt = switch_stmt;
> > p->cases = splay_tree_new (case_compare, NULL, NULL);
> > + p->outside_range_p = false;
> > switch_stack = p;
> > }
> >
> > @@ -3244,10 +3248,14 @@ pop_switch (void)
> >
> > /* Emit warnings as needed. */
> > switch_location = EXPR_LOC_OR_LOC (cs->switch_stmt, input_location);
> > + const bool bool_cond_p
> > + = (SWITCH_STMT_TYPE (cs->switch_stmt)
> > + && TREE_CODE (SWITCH_STMT_TYPE (cs->switch_stmt)) == BOOLEAN_TYPE);
> > if (!processing_template_decl)
> > c_do_switch_warnings (cs->cases, switch_location,
> > SWITCH_STMT_TYPE (cs->switch_stmt),
> > - SWITCH_STMT_COND (cs->switch_stmt));
> > + SWITCH_STMT_COND (cs->switch_stmt),
> > + bool_cond_p, cs->outside_range_p);
> >
> > splay_tree_delete (cs->cases);
> > switch_stack = switch_stack->next;
> > @@ -3312,7 +3320,8 @@ finish_case_label (location_t loc, tree low_value, tree high_value)
> > high_value = case_conversion (type, high_value);
> >
> > r = c_add_case_label (loc, switch_stack->cases, cond, type,
> > - low_value, high_value);
> > + low_value, high_value,
> > + &switch_stack->outside_range_p);
> >
> > /* After labels, make any new cleanups in the function go into their
> > own new (temporary) binding contour. */
> > diff --git gcc/cp/semantics.c gcc/cp/semantics.c
> > index 59ec9047..aa43022 100644
> > --- gcc/cp/semantics.c
> > +++ gcc/cp/semantics.c
> > @@ -1161,11 +1161,6 @@ finish_switch_cond (tree cond, tree switch_stmt)
> > orig_type = TREE_TYPE (cond);
> > if (cond != error_mark_node)
> > {
> > - /* Warn if the condition has boolean value. */
> > - if (TREE_CODE (orig_type) == BOOLEAN_TYPE)
> > - warning_at (input_location, OPT_Wswitch_bool,
> > - "switch condition has type bool");
> > -
> > /* [stmt.switch]
> >
> > Integral promotions are performed. */
> > diff --git gcc/function.c gcc/function.c
> > index 8baaed7..0b45abf 100644
> > --- gcc/function.c
> > +++ gcc/function.c
> > @@ -4934,7 +4934,7 @@ stack_protect_epilogue (void)
> >
> > /* Allow the target to compare Y with X without leaking either into
> > a register. */
> > - switch ((int) (HAVE_stack_protect_test != 0))
> > + switch (HAVE_stack_protect_test != 0)
> > {
> > case 1:
> > tmp = gen_stack_protect_test (x, y, label);
> > diff --git gcc/testsuite/c-c++-common/pr60439.c gcc/testsuite/c-c++-common/pr60439.c
> > index 3368a0b..68bd33c 100644
> > --- gcc/testsuite/c-c++-common/pr60439.c
> > +++ gcc/testsuite/c-c++-common/pr60439.c
> > @@ -1,5 +1,6 @@
> > /* PR c/60439 */
> > /* { dg-do compile } */
> > +/* { dg-prune-output "case label value exceeds" } */
> >
> > #ifndef __cplusplus
> > # define bool _Bool
> > @@ -11,18 +12,30 @@ void
> > f1 (bool b)
> > {
> > switch (b) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > }
> >
> > void
> > f2 (int a, int b)
> > {
> > switch (a && b) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch ((bool) (a && b)) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch ((a && b) || a) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > /* No warnings on following. */
> > switch ((int) (a && b))
> > break;
> > @@ -38,35 +51,65 @@ void
> > f3 (int a)
> > {
> > switch (!!a) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (!a) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > }
> >
> > void
> > f4 (void)
> > {
> > switch (foo ()) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > }
> >
> > void
> > f5 (int a)
> > {
> > switch (a == 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a != 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a > 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a < 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a <= 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a >= 3) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (foo (), foo (), a >= 42) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (a == 3, a & 4, a ^ 5, a)
> > break;
> > switch ((int) (a == 3))
> > @@ -79,11 +122,20 @@ void
> > f6 (bool b)
> > {
> > switch (b) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (!b) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > switch (b++) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > }
> >
> > void
> > @@ -91,7 +143,10 @@ f7 (void)
> > {
> > bool b;
> > switch (b = 1) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 3:
> > + break;
> > + }
> > }
> >
> > void
> > @@ -104,5 +159,8 @@ f8 (int i)
> > switch ((unsigned int) i)
> > break;
> > switch ((bool) i) /* { dg-warning "switch condition has" } */
> > - break;
> > + {
> > + case 11:
> > + break;
> > + }
> > }
> > diff --git gcc/testsuite/c-c++-common/pr66322.c gcc/testsuite/c-c++-common/pr66322.c
> > index e69de29..eb1e9e4 100644
> > --- gcc/testsuite/c-c++-common/pr66322.c
> > +++ gcc/testsuite/c-c++-common/pr66322.c
> > @@ -0,0 +1,144 @@
> > +/* PR c/66322 */
> > +/* { dg-do compile } */
> > +
> > +#ifndef __cplusplus
> > +# define bool _Bool
> > +# define true 1
> > +# define false 0
> > +#endif
> > +
> > +void
> > +nowarn (bool b)
> > +{
> > + switch (b)
> > + ;
> > +
> > + switch (b)
> > + {
> > + case true:
> > + case false:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case true:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case true:
> > + default:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case false:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case false:
> > + default:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + default:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case false ... true:
> > + break;
> > + }
> > +
> > + switch (b)
> > + {
> > + case 1:
> > + switch (b)
> > + {
> > + case true:
> > + default:
> > + break;
> > + }
> > + default:
> > + break;
> > + }
> > +}
> > +
> > +void
> > +warn (bool b)
> > +{
> > + switch (b) /* { dg-warning "switch condition has" } */
> > + {
> > + case true:
> > + case false:
> > + default:
> > + break;
> > + }
> > +
> > + switch (b) /* { dg-warning "switch condition has" } */
> > + {
> > + case false ... true:
> > + default:
> > + break;
> > + }
> > +}
> > +
> > +void
> > +warn2 (int n)
> > +{
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case 0 ... 2: /* { dg-warning "upper value" "" { target c++ } } */
> > + default:
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case 1 ... 10: /* { dg-warning "upper value" "" { target c++ } } */
> > + default:
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case 2: /* { dg-warning "case label" "" { target c++ } } */
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case 0:
> > + case 1:
> > + case -1: /* { dg-warning "case label" "" { target c++ } } */
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case -1 ... 1: /* { dg-warning "lower value" "" { target c++ } } */
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case -1 ... 0: /* { dg-warning "lower value" "" { target c++ } } */
> > + default:
> > + break;
> > + }
> > +
> > + switch (n == 2) /* { dg-warning "switch condition has" } */
> > + {
> > + case -10 ... -1: /* { dg-warning "case label" "" { target c++ } } */
> > + default:
> > + break;
> > + }
> > +}
> > diff --git gcc/testsuite/g++.dg/eh/scope1.C gcc/testsuite/g++.dg/eh/scope1.C
> > index 8d553d8..276e0d6 100644
> > --- gcc/testsuite/g++.dg/eh/scope1.C
> > +++ gcc/testsuite/g++.dg/eh/scope1.C
> > @@ -31,7 +31,7 @@ void f3 ()
> >
> > void f4 ()
> > {
> > - switch (C br = C()) /* { dg-warning "switch condition has" } */
> > + switch (C br = C())
> > {
> > default:
> > abort ();
Marek