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re PR c/70436 (-Wparentheses missing ambiguous else warning) 

PR c/70436
	* c-parser.c (c_parser_statement_after_labels): Add IF_P argument and
	adjust callers.
	(c_parser_statement): Likewise.
	(c_parser_c99_block_statement): Likewise.
	(c_parser_while_statement): Likewise.
	(c_parser_for_statement): Likewise.
	(c_parser_if_body): Don't set IF_P here.
	(c_parser_if_statement): Add IF_P argument.  Set IF_P here.  Warn
	about dangling else here.
	* c-tree.h (c_finish_if_stmt): Adjust declaration.
	* c-typeck.c (c_finish_if_stmt): Remove NESTED_IF parameter.  Don't
	warn about dangling else here.

	* testsuite/gcc.dg/Wparentheses-12.c: New test.
	* testsuite/gcc.dg/Wparentheses-13.c: New test.

From-SVN: r234949
This commit is contained in:
Marek Polacek 2016-04-13 16:00:52 +00:00 committed by Marek Polacek
parent 5267cfcc82
commit 99cd9857c0
7 changed files with 306 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
gcc/c/ChangeLog
View File

@ -1,3 +1,19 @@
2016-04-13 Marek Polacek <polacek@redhat.com>
PR c/70436
* c-parser.c (c_parser_statement_after_labels): Add IF_P argument and
adjust callers.
(c_parser_statement): Likewise.
(c_parser_c99_block_statement): Likewise.
(c_parser_while_statement): Likewise.
(c_parser_for_statement): Likewise.
(c_parser_if_body): Don't set IF_P here.
(c_parser_if_statement): Add IF_P argument. Set IF_P here. Warn
about dangling else here.
* c-tree.h (c_finish_if_stmt): Adjust declaration.
* c-typeck.c (c_finish_if_stmt): Remove NESTED_IF parameter. Don't
warn about dangling else here.
2016-04-04 Marek Polacek <polacek@redhat.com>
PR c/70307

119
gcc/c/c-parser.c
View File

@ -1301,13 +1301,14 @@ static void c_parser_initval (c_parser *, struct c_expr *,
static tree c_parser_compound_statement (c_parser *);
static void c_parser_compound_statement_nostart (c_parser *);
static void c_parser_label (c_parser *);
static void c_parser_statement (c_parser *);
static void c_parser_statement_after_labels (c_parser *, vec<tree> * = NULL);
static void c_parser_if_statement (c_parser *, vec<tree> *);
static void c_parser_statement (c_parser *, bool *);
static void c_parser_statement_after_labels (c_parser *, bool *,
vec<tree> * = NULL);
static void c_parser_if_statement (c_parser *, bool *, vec<tree> *);
static void c_parser_switch_statement (c_parser *);
static void c_parser_while_statement (c_parser *, bool);
static void c_parser_while_statement (c_parser *, bool, bool *);
static void c_parser_do_statement (c_parser *, bool);
static void c_parser_for_statement (c_parser *, bool);
static void c_parser_for_statement (c_parser *, bool, bool *);
static tree c_parser_asm_statement (c_parser *);
static tree c_parser_asm_operands (c_parser *);
static tree c_parser_asm_goto_operands (c_parser *);
@ -4853,7 +4854,7 @@ c_parser_compound_statement_nostart (c_parser *parser)
last_label = false;
last_stmt = true;
mark_valid_location_for_stdc_pragma (false);
c_parser_statement_after_labels (parser);
c_parser_statement_after_labels (parser, NULL);
}
parser->error = false;
@ -5095,25 +5096,35 @@ c_parser_label (c_parser *parser)
statement:
transaction-statement
transaction-cancel-statement
*/
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static void
c_parser_statement (c_parser *parser)
c_parser_statement (c_parser *parser, bool *if_p)
{
c_parser_all_labels (parser);
c_parser_statement_after_labels (parser);
c_parser_statement_after_labels (parser, if_p, NULL);
}
/* Parse a statement, other than a labeled statement. CHAIN is a vector
of if-else-if conditions. */
of if-else-if conditions.
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static void
c_parser_statement_after_labels (c_parser *parser, vec<tree> *chain)
c_parser_statement_after_labels (c_parser *parser, bool *if_p,
vec<tree> *chain)
{
location_t loc = c_parser_peek_token (parser)->location;
tree stmt = NULL_TREE;
bool in_if_block = parser->in_if_block;
parser->in_if_block = false;
if (if_p != NULL)
*if_p = false;
switch (c_parser_peek_token (parser)->type)
{
case CPP_OPEN_BRACE:
@ -5123,19 +5134,19 @@ c_parser_statement_after_labels (c_parser *parser, vec<tree> *chain)
switch (c_parser_peek_token (parser)->keyword)
{
case RID_IF:
c_parser_if_statement (parser, chain);
c_parser_if_statement (parser, if_p, chain);
break;
case RID_SWITCH:
c_parser_switch_statement (parser);
break;
case RID_WHILE:
c_parser_while_statement (parser, false);
c_parser_while_statement (parser, false, if_p);
break;
case RID_DO:
c_parser_do_statement (parser, false);
break;
case RID_FOR:
c_parser_for_statement (parser, false);
c_parser_for_statement (parser, false, if_p);
break;
case RID_CILK_FOR:
if (!flag_cilkplus)
@ -5321,14 +5332,18 @@ c_parser_paren_condition (c_parser *parser)
return cond;
}
/* Parse a statement which is a block in C99. */
/* Parse a statement which is a block in C99.
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static tree
c_parser_c99_block_statement (c_parser *parser)
c_parser_c99_block_statement (c_parser *parser, bool *if_p)
{
tree block = c_begin_compound_stmt (flag_isoc99);
location_t loc = c_parser_peek_token (parser)->location;
c_parser_statement (parser);
c_parser_statement (parser, if_p);
return c_end_compound_stmt (loc, block, flag_isoc99);
}
@ -5338,7 +5353,11 @@ c_parser_c99_block_statement (c_parser *parser)
we handle an empty body specially for the sake of -Wempty-body
warnings, and (d) we call parser_compound_statement directly
because c_parser_statement_after_labels resets
parser->in_if_block. */
parser->in_if_block.
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static tree
c_parser_if_body (c_parser *parser, bool *if_p,
@ -5350,7 +5369,6 @@ c_parser_if_body (c_parser *parser, bool *if_p,
= get_token_indent_info (c_parser_peek_token (parser));
c_parser_all_labels (parser);
*if_p = c_parser_next_token_is_keyword (parser, RID_IF);
if (c_parser_next_token_is (parser, CPP_SEMICOLON))
{
location_t loc = c_parser_peek_token (parser)->location;
@ -5363,7 +5381,7 @@ c_parser_if_body (c_parser *parser, bool *if_p,
else if (c_parser_next_token_is (parser, CPP_OPEN_BRACE))
add_stmt (c_parser_compound_statement (parser));
else
c_parser_statement_after_labels (parser);
c_parser_statement_after_labels (parser, if_p);
token_indent_info next_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
@ -5397,7 +5415,7 @@ c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo,
c_parser_consume_token (parser);
}
else
c_parser_statement_after_labels (parser, chain);
c_parser_statement_after_labels (parser, NULL, chain);
token_indent_info next_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
@ -5412,15 +5430,18 @@ c_parser_else_body (c_parser *parser, const token_indent_info &else_tinfo,
if ( expression ) statement
if ( expression ) statement else statement
CHAIN is a vector of if-else-if conditions. */
CHAIN is a vector of if-else-if conditions.
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static void
c_parser_if_statement (c_parser *parser, vec<tree> *chain)
c_parser_if_statement (c_parser *parser, bool *if_p, vec<tree> *chain)
{
tree block;
location_t loc;
tree cond;
bool first_if = false;
bool nested_if = false;
tree first_body, second_body;
bool in_if_block;
tree if_stmt;
@ -5439,7 +5460,7 @@ c_parser_if_statement (c_parser *parser, vec<tree> *chain)
}
in_if_block = parser->in_if_block;
parser->in_if_block = true;
first_body = c_parser_if_body (parser, &first_if, if_tinfo);
first_body = c_parser_if_body (parser, &nested_if, if_tinfo);
parser->in_if_block = in_if_block;
if (warn_duplicated_cond)
@ -5470,10 +5491,22 @@ c_parser_if_statement (c_parser *parser, vec<tree> *chain)
}
}
second_body = c_parser_else_body (parser, else_tinfo, chain);
/* Set IF_P to true to indicate that this if statement has an
else clause. This may trigger the Wparentheses warning
below when we get back up to the parent if statement. */
if (if_p != NULL)
*if_p = true;
}
else
{
second_body = NULL_TREE;
/* Diagnose an ambiguous else if if-then-else is nested inside
if-then. */
if (nested_if)
warning_at (loc, OPT_Wparentheses,
"suggest explicit braces to avoid ambiguous %<else%>");
if (warn_duplicated_cond)
{
/* This if statement does not have an else clause. We don't
@ -5482,7 +5515,7 @@ c_parser_if_statement (c_parser *parser, vec<tree> *chain)
chain = NULL;
}
}
c_finish_if_stmt (loc, cond, first_body, second_body, first_if);
c_finish_if_stmt (loc, cond, first_body, second_body);
if_stmt = c_end_compound_stmt (loc, block, flag_isoc99);
/* If the if statement contains array notations, then we expand them. */
@ -5533,7 +5566,7 @@ c_parser_switch_statement (c_parser *parser)
c_start_case (switch_loc, switch_cond_loc, expr, explicit_cast_p);
save_break = c_break_label;
c_break_label = NULL_TREE;
body = c_parser_c99_block_statement (parser);
body = c_parser_c99_block_statement (parser, NULL/*if??*/);
c_finish_case (body, ce.original_type);
if (c_break_label)
{
@ -5550,10 +5583,13 @@ c_parser_switch_statement (c_parser *parser)
while-statement:
while (expression) statement
*/
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static void
c_parser_while_statement (c_parser *parser, bool ivdep)
c_parser_while_statement (c_parser *parser, bool ivdep, bool *if_p)
{
tree block, cond, body, save_break, save_cont;
location_t loc;
@ -5580,7 +5616,7 @@ c_parser_while_statement (c_parser *parser, bool ivdep)
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
body = c_parser_c99_block_statement (parser);
body = c_parser_c99_block_statement (parser, if_p);
c_finish_loop (loc, cond, NULL, body, c_break_label, c_cont_label, true);
add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
@ -5615,7 +5651,7 @@ c_parser_do_statement (c_parser *parser, bool ivdep)
c_break_label = NULL_TREE;
save_cont = c_cont_label;
c_cont_label = NULL_TREE;
body = c_parser_c99_block_statement (parser);
body = c_parser_c99_block_statement (parser, NULL);
c_parser_require_keyword (parser, RID_WHILE, "expected %<while%>");
new_break = c_break_label;
c_break_label = save_break;
@ -5690,10 +5726,13 @@ c_parser_do_statement (c_parser *parser, bool ivdep)
like the beginning of the for-statement, and we can tell it is a
foreach-statement only because the initial declaration or
expression is terminated by 'in' instead of ';'.
*/
IF_P is used to track whether there's a (possibly labeled) if statement
which is not enclosed in braces and has an else clause. This is used to
implement -Wparentheses. */
static void
c_parser_for_statement (c_parser *parser, bool ivdep)
c_parser_for_statement (c_parser *parser, bool ivdep, bool *if_p)
{
tree block, cond, incr, save_break, save_cont, body;
/* The following are only used when parsing an ObjC foreach statement. */
@ -5869,7 +5908,7 @@ c_parser_for_statement (c_parser *parser, bool ivdep)
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
body = c_parser_c99_block_statement (parser);
body = c_parser_c99_block_statement (parser, if_p);
if (is_foreach_statement)
objc_finish_foreach_loop (loc, object_expression, collection_expression, body, c_break_label, c_cont_label);
@ -10118,9 +10157,9 @@ c_parser_pragma (c_parser *parser, enum pragma_context context)
return false;
}
if (c_parser_next_token_is_keyword (parser, RID_FOR))
c_parser_for_statement (parser, true);
c_parser_for_statement (parser, true, NULL);
else if (c_parser_next_token_is_keyword (parser, RID_WHILE))
c_parser_while_statement (parser, true);
c_parser_while_statement (parser, true, NULL);
else
c_parser_do_statement (parser, true);
return false;
@ -13441,7 +13480,7 @@ static tree
c_parser_omp_structured_block (c_parser *parser)
{
tree stmt = push_stmt_list ();
c_parser_statement (parser);
c_parser_statement (parser, NULL);
return pop_stmt_list (stmt);
}
@ -14843,7 +14882,7 @@ c_parser_omp_for_loop (location_t loc, c_parser *parser, enum tree_code code,
add_stmt (c_end_compound_stmt (here, stmt, true));
}
else
add_stmt (c_parser_c99_block_statement (parser));
add_stmt (c_parser_c99_block_statement (parser, NULL));
if (c_cont_label)
{
tree t = build1 (LABEL_EXPR, void_type_node, c_cont_label);
@ -15397,7 +15436,7 @@ c_parser_omp_parallel (location_t loc, c_parser *parser,
}
block = c_begin_omp_parallel ();
c_parser_statement (parser);
c_parser_statement (parser, NULL);
stmt = c_finish_omp_parallel (loc, clauses, block);
return stmt;
@ -15458,7 +15497,7 @@ c_parser_omp_task (location_t loc, c_parser *parser)
"#pragma omp task");
block = c_begin_omp_task ();
c_parser_statement (parser);
c_parser_statement (parser, NULL);
return c_finish_omp_task (loc, clauses, block);
}

2
gcc/c/c-tree.h
View File

@ -641,7 +641,7 @@ extern tree build_asm_stmt (tree, tree);
extern int c_types_compatible_p (tree, tree);
extern tree c_begin_compound_stmt (bool);
extern tree c_end_compound_stmt (location_t, tree, bool);
extern void c_finish_if_stmt (location_t, tree, tree, tree, bool);
extern void c_finish_if_stmt (location_t, tree, tree, tree);
extern void c_finish_loop (location_t, tree, tree, tree, tree, tree, bool);
extern tree c_begin_stmt_expr (void);
extern tree c_finish_stmt_expr (location_t, tree);

38
gcc/c/c-typeck.c
View File

@ -9974,12 +9974,11 @@ c_finish_case (tree body, tree type)
/* Emit an if statement. IF_LOCUS is the location of the 'if'. COND,
THEN_BLOCK and ELSE_BLOCK are expressions to be used; ELSE_BLOCK
may be null. NESTED_IF is true if THEN_BLOCK contains another IF
statement, and was not surrounded with parenthesis. */
may be null. */
void
c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
tree else_block, bool nested_if)
tree else_block)
{
tree stmt;
@ -10011,39 +10010,6 @@ c_finish_if_stmt (location_t if_locus, tree cond, tree then_block,
return;
}
}
/* Diagnose an ambiguous else if if-then-else is nested inside if-then. */
if (warn_parentheses && nested_if && else_block == NULL)
{
tree inner_if = then_block;
/* We know from the grammar productions that there is an IF nested
within THEN_BLOCK. Due to labels and c99 conditional declarations,
it might not be exactly THEN_BLOCK, but should be the last
non-container statement within. */
while (1)
switch (TREE_CODE (inner_if))
{
case COND_EXPR:
goto found;
case BIND_EXPR:
inner_if = BIND_EXPR_BODY (inner_if);
break;
case STATEMENT_LIST:
inner_if = expr_last (then_block);
break;
case TRY_FINALLY_EXPR:
case TRY_CATCH_EXPR:
inner_if = TREE_OPERAND (inner_if, 0);
break;
default:
gcc_unreachable ();
}
found:
if (COND_EXPR_ELSE (inner_if))
warning_at (if_locus, OPT_Wparentheses,
"suggest explicit braces to avoid ambiguous %<else%>");
}
stmt = build3 (COND_EXPR, void_type_node, cond, then_block, else_block);
SET_EXPR_LOCATION (stmt, if_locus);

6
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,9 @@
2016-04-13 Marek Polacek <polacek@redhat.com>
PR c/70436
* testsuite/gcc.dg/Wparentheses-12.c: New test.
* testsuite/gcc.dg/Wparentheses-13.c: New test.
2016-04-13 Ilya Enkovich <ilya.enkovich@intel.com>
* gcc.target/i386/avx512bw-kunpckdq-2.c: New test.

135
gcc/testsuite/gcc.dg/Wparentheses-12.c Normal file
View File

@ -0,0 +1,135 @@
/* PR c/70436 */
/* { dg-options "-Wparentheses" } */
int a, b, c;
void bar (void);
void baz (void);
void
foo (void)
{
int i, j;
if (a) /* { dg-warning "ambiguous" } */
for (;;)
if (b)
bar ();
else
baz ();
if (a) /* { dg-warning "ambiguous" } */
while (1)
if (b)
bar ();
else
baz ();
if (a) /* { dg-warning "ambiguous" } */
while (1)
for (;;)
if (b)
bar ();
else
baz ();
if (a) /* { dg-warning "ambiguous" } */
while (1)
while (1)
if (b)
bar ();
else
baz ();
if (a) /* { dg-warning "ambiguous" } */
for (i = 0; i < 10; i++)
for (j = 0; j < 10; j++)
if (b)
bar ();
else
baz ();
if (a)
for (i = 0; i < 10; i++)
if (b) /* { dg-warning "ambiguous" } */
for (j = 0; j < 10; j++)
if (c)
bar ();
else
baz ();
if (a) /* { dg-warning "ambiguous" } */
for (i = 0; i < 10; i++)
if (b)
for (j = 0; j < 10; j++)
if (c)
bar ();
else
baz ();
else
bar ();
if (a) /* { dg-warning "ambiguous" } */
for (;;)
if (b)
while (1)
if (a)
bar ();
else
baz ();
else
bar ();
if (a) /* { dg-warning "ambiguous" } */
for (;;)
if (b)
while (1)
{
if (a) { bar (); } else { baz (); }
}
else
bar ();
if (a)
for (;;)
if (b)
bar ();
else
baz ();
else bar ();
if (a)
while (1)
if (b)
bar ();
else
baz ();
else bar ();
if (a)
for (;;)
{
if (b)
bar ();
else
baz ();
}
if (a)
{
for (;;)
if (b)
bar ();
}
else baz ();
if (a)
do
if (b) bar (); else baz ();
while (b);
if (a)
do
if (b) bar ();
while (b);
else baz ();
}

67
gcc/testsuite/gcc.dg/Wparentheses-13.c Normal file
View File

@ -0,0 +1,67 @@
/* PR c/70436 */
/* { dg-options "-Wparentheses" } */
int a, b, c;
void bar (int);
void
foo (void)
{
if (a) /* { dg-warning "ambiguous" } */
if (b)
{
if (c)
bar (0);
}
else
bar (1);
if (a > 0)
if (a > 1)
if (a > 2)
if (a > 3)
if (a > 4)
if (a > 5) /* { dg-warning "ambiguous" } */
if (a > 6)
while (1)
bar (0);
else
bar (1);
if (a) /* { dg-warning "ambiguous" } */
if (b)
switch (c);
else
bar (1);
switch (a)
{
default:
if (b) /* { dg-warning "ambiguous" } */
if (c)
for (;;)
bar (0);
else
bar (1);
}
if (a) /* { dg-warning "ambiguous" } */
if (a)
{
bar (2);
}
else
bar (3);
if (a)
do if (b) bar (4); while (1);
else bar (5);
do
{
if (a)
if (b) /* { dg-warning "ambiguous" } */
if (c) for (;;) bar (6);
else bar (7);
} while (0);
}