On Thu, Jun 08, 2017 at 01:24:09PM -0400, David Malcolm wrote:
> On Thu, 2017-06-08 at 18:49 +0200, Marek Polacek wrote:
> > This is the hopefully last incarnation of the patch. The change from
> > the
> > last time[0] is simpy that I've added a new test and the warning has
> > been
> > renamed to -Wmultistatement-macros.
> >
> > David - any another comments?
>
> Thanks for working on this; looks useful.
>
> The new name is more accurate, but is rather long; oh well. As part of
> -Wall, users won't typically have to type it, so that's OK.
Yeah, I'm not in love with the name either, but it's the best we could come up
with.
> [...]
>
> > diff --git gcc/c-family/c-warn.c gcc/c-family/c-warn.c
> > index 35321a6..d883330 100644
> > --- gcc/c-family/c-warn.c
> > +++ gcc/c-family/c-warn.c
> [...]
>
> > + if (warning_at (body_loc, OPT_Wmultistatement_macros,
> > + "macro expands to multiple statements"))
> > + inform (guard_loc, "some parts of macro expansion are not
> > guarded by "
> > + "this conditional");
>
> Is the guard necessarily a "conditional"? I take a "conditional" to
> mean an "if"; the guard could be a "for" or a "while" (or an "else",
> which still seems something of a stretch to me to call a
> "conditional").
>
> Suggestion: word "this conditional" as "this %qs clause" and either (a)
> rework the code in c-indentation.c's guard_tinfo_to_string so that it's
> shared between these two warnings (i.e. to go from a RID_ to a const
> char *), or (b) just pass in a const char * identifying the guard
> clause token.
I prefer (a) so I tweaked guard_tinfo_to_string. Of course, the name is
not that accurate anymore...
> > diff --git gcc/c-family/c.opt gcc/c-family/c.opt
> > index 37bb236..9dbe211 100644
> > --- gcc/c-family/c.opt
> > +++ gcc/c-family/c.opt
> > @@ -698,6 +698,10 @@ Wmissing-field-initializers
> > C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning
> > EnabledBy(Wextra)
> > Warn about missing fields in struct initializers.
> >
> > +Wmultistatement-macros
> > +C ObjC C++ ObjC++ Var(warn_multistatement_macros) Warning
> > LangEnabledBy(C ObjC C++ ObjC++,Wall)
> > +Warn about macros expanding to multiple statements in a body of a
> > conditional such as if, else, while, or for.
>
> Likewise; is "conditional" the right word here? Also, whether of not
> the statements are actually "in" the body of the guard is the issue
> here.
>
> How about:
>
> "Warn about unsafe multiple statement macros that appear to be guarded
> by a clause such as if, else, while, or for, in which only the first
> statement is actually guarded after the macro is expanded."
>
> or somesuch?
I think this is too long for c.opt, so I used:
"Warn about unsafe macros expanding to multiple statements used as a body
of a clause such as if, else, while, switch, or for."
And I forgot to mention "switch" there.
> > diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
> > index c116882..2fe16dd 100644
> > --- gcc/doc/invoke.texi
> > +++ gcc/doc/invoke.texi
> > @@ -4496,6 +4497,29 @@ This warning is enabled by @option{-Wall}.
> > @opindex Wno-missing-include-dirs
> > Warn if a user-supplied include directory does not exist.
> >
> > +@item -Wmultistatement-macros
> > +@opindex Wmultistatement-macros
> > +@opindex Wno-multistatement-macros
> > +Warn about macros expanding to multiple statements in a body of a
> > conditional,
> > +such as @code{if}, @code{else}, @code{for}, or @code{while}.
>
> (as above).
But I used the longer form here.
> > +For example:
> > +
> > +@smallexample
> > +#define DOIT x++; y++
> > +if (c)
> > + DOIT;
> > +@end smallexample
> > +
> > +will increment @code{y} unconditionally, not just when @code{c}
> > holds.
> > +The can usually be fixed by wrapping the macro in a do-while loop:
> > +@smallexample
> > +#define DOIT do @{ x++; y++; @} while (0)
> > +if (c)
> > + DOIT;
> > +@end smallexample
> > +
> > +This warning is enabled by @option{-Wall} in C and C++.
> > +
> > @item -Wparentheses
> > @opindex Wparentheses
> > @opindex Wno-parentheses
>
> Hope this is constructive
As usually ;).
Updated version of the patch here. Thanks,
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2017-06-13 Marek Polacek <pola...@redhat.com>
PR c/80116
* c-common.h (warn_for_multistatement_macros): Declare.
* c-warn.c: Include "c-family/c-indentation.h".
(warn_for_multistatement_macros): New function.
* c.opt (Wmultistatement-macros): New option.
* c-indentation.c (guard_tinfo_to_string): No longer static.
Change the parameter type to "enum rid". Handle RID_SWITCH.
* c-indentation.h (guard_tinfo_to_string): Declare.
* c-parser.c (c_parser_if_body): Set the location of the
body of the conditional after parsing all the labels. Call
warn_for_multistatement_macros.
(c_parser_else_body): Likewise.
(c_parser_switch_statement): Likewise.
(c_parser_while_statement): Likewise.
(c_parser_for_statement): Likewise.
(c_parser_statement): Add a default argument. Save the location
after labels have been parsed.
(c_parser_c99_block_statement): Likewise.
* parser.c (cp_parser_statement): Add a default argument. Save the
location of the expression-statement after labels have been parsed.
(cp_parser_implicitly_scoped_statement): Set the location of the
body of the conditional after parsing all the labels. Call
warn_for_multistatement_macros.
(cp_parser_already_scoped_statement): Likewise.
* doc/invoke.texi: Document -Wmultistatement-macros.
* c-c++-common/Wmultistatement-macros-1.c: New test.
* c-c++-common/Wmultistatement-macros-2.c: New test.
* c-c++-common/Wmultistatement-macros-3.c: New test.
* c-c++-common/Wmultistatement-macros-4.c: New test.
* c-c++-common/Wmultistatement-macros-5.c: New test.
* c-c++-common/Wmultistatement-macros-6.c: New test.
* c-c++-common/Wmultistatement-macros-7.c: New test.
* c-c++-common/Wmultistatement-macros-8.c: New test.
* c-c++-common/Wmultistatement-macros-9.c: New test.
* c-c++-common/Wmultistatement-macros-10.c: New test.
* c-c++-common/Wmultistatement-macros-11.c: New test.
diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
index 79072e6..f046a37 100644
--- gcc/c-family/c-common.h
+++ gcc/c-family/c-common.h
@@ -1539,6 +1539,8 @@ extern bool maybe_warn_shift_overflow (location_t, tree,
tree);
extern void warn_duplicated_cond_add_or_warn (location_t, tree, vec<tree> **);
extern bool diagnose_mismatched_attributes (tree, tree);
extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
+extern void warn_for_multistatement_macros (location_t, location_t,
+ location_t, enum rid);
/* In c-attribs.c. */
extern bool attribute_takes_identifier_p (const_tree);
diff --git gcc/c-family/c-indentation.c gcc/c-family/c-indentation.c
index 8300788..7ca21e8 100644
--- gcc/c-family/c-indentation.c
+++ gcc/c-family/c-indentation.c
@@ -542,10 +542,10 @@ should_warn_for_misleading_indentation (const
token_indent_info &guard_tinfo,
/* Return the string identifier corresponding to the given guard token. */
-static const char *
-guard_tinfo_to_string (const token_indent_info &guard_tinfo)
+const char *
+guard_tinfo_to_string (enum rid keyword)
{
- switch (guard_tinfo.keyword)
+ switch (keyword)
{
case RID_FOR:
return "for";
@@ -557,6 +557,8 @@ guard_tinfo_to_string (const token_indent_info &guard_tinfo)
return "while";
case RID_DO:
return "do";
+ case RID_SWITCH:
+ return "switch";
default:
gcc_unreachable ();
}
@@ -605,10 +607,10 @@ warn_for_misleading_indentation (const token_indent_info
&guard_tinfo,
{
if (warning_at (guard_tinfo.location, OPT_Wmisleading_indentation,
"this %qs clause does not guard...",
- guard_tinfo_to_string (guard_tinfo)))
+ guard_tinfo_to_string (guard_tinfo.keyword)))
inform (next_tinfo.location,
"...this statement, but the latter is misleadingly indented"
" as if it were guarded by the %qs",
- guard_tinfo_to_string (guard_tinfo));
+ guard_tinfo_to_string (guard_tinfo.keyword));
}
}
diff --git gcc/c-family/c-indentation.h gcc/c-family/c-indentation.h
index a436697..e4cad26 100644
--- gcc/c-family/c-indentation.h
+++ gcc/c-family/c-indentation.h
@@ -48,5 +48,7 @@ extern void
warn_for_misleading_indentation (const token_indent_info &guard_tinfo,
const token_indent_info &body_tinfo,
const token_indent_info &next_tinfo);
+extern const char *
+guard_tinfo_to_string (enum rid keyword);
#endif /* ! GCC_C_INDENTATION_H */
diff --git gcc/c-family/c-warn.c gcc/c-family/c-warn.c
index 35321a6..72af573 100644
--- gcc/c-family/c-warn.c
+++ gcc/c-family/c-warn.c
@@ -31,6 +31,7 @@ along with GCC; see the file COPYING3. If not see
#include "asan.h"
#include "gcc-rich-location.h"
#include "gimplify.h"
+#include "c-family/c-indentation.h"
/* Print a warning if a constant expression had overflow in folding.
Invoke this function on every expression that the language
@@ -2401,3 +2402,91 @@ do_warn_duplicated_branches_r (tree *tp, int *, void *)
do_warn_duplicated_branches (*tp);
return NULL_TREE;
}
+
+/* Implementation of -Wmultistatement-macros. This warning warns about
+ cases when a macro expands to multiple statements not wrapped in
+ do {} while (0) or ({ }) and is used as a body of if/else/for/while
+ conditionals. For example,
+
+ #define DOIT x++; y++
+
+ if (c)
+ DOIT;
+
+ will increment y unconditionally.
+
+ BODY_LOC is the location of the first token in the body after labels
+ have been parsed, NEXT_LOC is the location of the next token after the
+ body of the conditional has been parsed, and GUARD_LOC is the location
+ of the conditional. */
+
+void
+warn_for_multistatement_macros (location_t body_loc, location_t next_loc,
+ location_t guard_loc, enum rid keyword)
+{
+ if (!warn_multistatement_macros)
+ return;
+
+ /* Ain't got time to waste. We only care about macros here. */
+ if (!from_macro_expansion_at (body_loc)
+ || !from_macro_expansion_at (next_loc))
+ return;
+
+ /* Let's skip macros defined in system headers. */
+ if (in_system_header_at (body_loc)
+ || in_system_header_at (next_loc))
+ return;
+
+ /* Find the actual tokens in the macro definition. BODY_LOC and
+ NEXT_LOC have to come from the same spelling location, but they
+ will resolve to different locations in the context of the macro
+ definition. */
+ location_t body_loc_exp
+ = linemap_resolve_location (line_table, body_loc,
+ LRK_MACRO_DEFINITION_LOCATION, NULL);
+ location_t next_loc_exp
+ = linemap_resolve_location (line_table, next_loc,
+ LRK_MACRO_DEFINITION_LOCATION, NULL);
+ location_t guard_loc_exp
+ = linemap_resolve_location (line_table, guard_loc,
+ LRK_MACRO_DEFINITION_LOCATION, NULL);
+
+ /* These are some funky cases we don't want to warn about. */
+ if (body_loc_exp == guard_loc_exp
+ || next_loc_exp == guard_loc_exp
+ || body_loc_exp == next_loc_exp)
+ return;
+
+ /* Find the macro map for the macro expansion BODY_LOC. */
+ const line_map *map = linemap_lookup (line_table, body_loc);
+ const line_map_macro *macro_map = linemap_check_macro (map);
+
+ /* Now see if the following token is coming from the same macro
+ expansion. If it is, it's a problem, because it should've been
+ parsed at this point. We only look at odd-numbered indexes
+ within the MACRO_MAP_LOCATIONS array, i.e. the spelling locations
+ of the tokens. */
+ bool found_guard = false;
+ bool found_next = false;
+ for (unsigned int i = 1;
+ i < 2 * MACRO_MAP_NUM_MACRO_TOKENS (macro_map);
+ i += 2)
+ {
+ if (MACRO_MAP_LOCATIONS (macro_map)[i] == next_loc_exp)
+ found_next = true;
+ if (MACRO_MAP_LOCATIONS (macro_map)[i] == guard_loc_exp)
+ found_guard = true;
+ }
+
+ /* The conditional itself must not come from the same expansion, because
+ we don't want to warn about
+ #define IF if (x) x++; y++
+ and similar. */
+ if (!found_next || found_guard)
+ return;
+
+ if (warning_at (body_loc, OPT_Wmultistatement_macros,
+ "macro expands to multiple statements"))
+ inform (guard_loc, "some parts of macro expansion are not guarded by "
+ "this %qs clause", guard_tinfo_to_string (keyword));
+}
diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 37bb236..34b4a61 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -698,6 +698,10 @@ Wmissing-field-initializers
C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning
EnabledBy(Wextra)
Warn about missing fields in struct initializers.
+Wmultistatement-macros
+C ObjC C++ ObjC++ Var(warn_multistatement_macros) Warning LangEnabledBy(C ObjC
C++ ObjC++,Wall)
+Warn about unsafe macros expanding to multiple statements used as a body of a
clause such as if, else, while, switch, or for.
+
Wmultiple-inheritance
C++ ObjC++ Var(warn_multiple_inheritance) Warning
Warn on direct multiple inheritance.
diff --git gcc/c/c-parser.c gcc/c/c-parser.c
index 6f954f2..f8fbc92 100644
--- gcc/c/c-parser.c
+++ gcc/c/c-parser.c
@@ -1218,9 +1218,11 @@ 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 *, bool *);
+static void c_parser_statement (c_parser *, bool *, location_t * = NULL);
static void c_parser_statement_after_labels (c_parser *, bool *,
vec<tree> * = NULL);
+static tree c_parser_c99_block_statement (c_parser *, bool *,
+ location_t * = NULL);
static void c_parser_if_statement (c_parser *, bool *, vec<tree> *);
static void c_parser_switch_statement (c_parser *, bool *);
static void c_parser_while_statement (c_parser *, bool, bool *);
@@ -5204,9 +5206,11 @@ c_parser_label (c_parser *parser)
implement -Wparentheses. */
static void
-c_parser_statement (c_parser *parser, bool *if_p)
+c_parser_statement (c_parser *parser, bool *if_p, location_t *loc_after_labels)
{
c_parser_all_labels (parser);
+ if (loc_after_labels)
+ *loc_after_labels = c_parser_peek_token (parser)->location;
c_parser_statement_after_labels (parser, if_p, NULL);
}
@@ -5466,11 +5470,12 @@ c_parser_paren_condition (c_parser *parser)
implement -Wparentheses. */
static tree
-c_parser_c99_block_statement (c_parser *parser, bool *if_p)
+c_parser_c99_block_statement (c_parser *parser, bool *if_p,
+ location_t *loc_after_labels)
{
tree block = c_begin_compound_stmt (flag_isoc99);
location_t loc = c_parser_peek_token (parser)->location;
- c_parser_statement (parser, if_p);
+ c_parser_statement (parser, if_p, loc_after_labels);
return c_end_compound_stmt (loc, block, flag_isoc99);
}
@@ -5492,6 +5497,7 @@ c_parser_if_body (c_parser *parser, bool *if_p,
{
tree block = c_begin_compound_stmt (flag_isoc99);
location_t body_loc = c_parser_peek_token (parser)->location;
+ location_t body_loc_after_labels = UNKNOWN_LOCATION;
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
@@ -5508,11 +5514,18 @@ 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, if_p);
+ {
+ body_loc_after_labels = c_parser_peek_token (parser)->location;
+ c_parser_statement_after_labels (parser, if_p);
+ }
token_indent_info next_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
warn_for_misleading_indentation (if_tinfo, body_tinfo, next_tinfo);
+ if (body_loc_after_labels != UNKNOWN_LOCATION
+ && next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (body_loc_after_labels, next_tinfo.location,
+ if_tinfo.location, RID_IF);
return c_end_compound_stmt (body_loc, block, flag_isoc99);
}
@@ -5530,6 +5543,7 @@ c_parser_else_body (c_parser *parser, const
token_indent_info &else_tinfo,
tree block = c_begin_compound_stmt (flag_isoc99);
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
+ location_t body_loc_after_labels = UNKNOWN_LOCATION;
c_parser_all_labels (parser);
if (c_parser_next_token_is (parser, CPP_SEMICOLON))
@@ -5542,11 +5556,18 @@ 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, NULL, chain);
+ {
+ body_loc_after_labels = c_parser_peek_token (parser)->location;
+ c_parser_statement_after_labels (parser, NULL, chain);
+ }
token_indent_info next_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
warn_for_misleading_indentation (else_tinfo, body_tinfo, next_tinfo);
+ if (body_loc_after_labels != UNKNOWN_LOCATION
+ && next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (body_loc_after_labels, next_tinfo.location,
+ else_tinfo.location, RID_ELSE);
return c_end_compound_stmt (body_loc, block, flag_isoc99);
}
@@ -5732,7 +5753,13 @@ c_parser_switch_statement (c_parser *parser, bool *if_p)
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, if_p);
+ location_t loc_after_labels;
+ bool open_brace_p = c_parser_peek_token (parser)->type == CPP_OPEN_BRACE;
+ body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
+ location_t next_loc = c_parser_peek_token (parser)->location;
+ if (!open_brace_p && c_parser_peek_token (parser)->type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (loc_after_labels, next_loc, switch_loc,
+ RID_SWITCH);
c_finish_case (body, ce.original_type);
if (c_break_label)
{
@@ -5783,7 +5810,8 @@ c_parser_while_statement (c_parser *parser, bool ivdep,
bool *if_p)
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
- body = c_parser_c99_block_statement (parser, if_p);
+ location_t loc_after_labels;
+ body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
c_finish_loop (loc, cond, NULL, body, c_break_label, c_cont_label, true);
add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
c_parser_maybe_reclassify_token (parser);
@@ -5792,6 +5820,10 @@ c_parser_while_statement (c_parser *parser, bool ivdep,
bool *if_p)
= get_token_indent_info (c_parser_peek_token (parser));
warn_for_misleading_indentation (while_tinfo, body_tinfo, next_tinfo);
+ if (next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
+ while_tinfo.location, RID_WHILE);
+
c_break_label = save_break;
c_cont_label = save_cont;
}
@@ -6076,7 +6108,8 @@ c_parser_for_statement (c_parser *parser, bool ivdep,
bool *if_p)
token_indent_info body_tinfo
= get_token_indent_info (c_parser_peek_token (parser));
- body = c_parser_c99_block_statement (parser, if_p);
+ location_t loc_after_labels;
+ body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
if (is_foreach_statement)
objc_finish_foreach_loop (loc, object_expression, collection_expression,
body, c_break_label, c_cont_label);
@@ -6089,6 +6122,10 @@ c_parser_for_statement (c_parser *parser, bool ivdep,
bool *if_p)
= get_token_indent_info (c_parser_peek_token (parser));
warn_for_misleading_indentation (for_tinfo, body_tinfo, next_tinfo);
+ if (next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
+ for_tinfo.location, RID_FOR);
+
c_break_label = save_break;
c_cont_label = save_cont;
}
diff --git gcc/cp/parser.c gcc/cp/parser.c
index d02ad36..1107c03 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -2102,7 +2102,7 @@ static void cp_parser_lambda_body
/* Statements [gram.stmt.stmt] */
static void cp_parser_statement
- (cp_parser *, tree, bool, bool *, vec<tree> * = NULL);
+ (cp_parser *, tree, bool, bool *, vec<tree> * = NULL, location_t * = NULL);
static void cp_parser_label_for_labeled_statement
(cp_parser *, tree);
static tree cp_parser_expression_statement
@@ -10535,7 +10535,8 @@ cp_parser_lambda_body (cp_parser* parser, tree
lambda_expr)
static void
cp_parser_statement (cp_parser* parser, tree in_statement_expr,
- bool in_compound, bool *if_p, vec<tree> *chain)
+ bool in_compound, bool *if_p, vec<tree> *chain,
+ location_t *loc_after_labels)
{
tree statement, std_attrs = NULL_TREE;
cp_token *token;
@@ -10728,6 +10729,10 @@ cp_parser_statement (cp_parser* parser, tree
in_statement_expr,
if (cp_parser_parse_definitely (parser))
return;
}
+ /* All preceding labels have been parsed at this point. */
+ if (loc_after_labels != NULL)
+ *loc_after_labels = statement_location;
+
/* Look for an expression-statement instead. */
statement = cp_parser_expression_statement (parser, in_statement_expr);
@@ -12268,6 +12273,7 @@ cp_parser_implicitly_scoped_statement (cp_parser*
parser, bool *if_p,
{
tree statement;
location_t body_loc = cp_lexer_peek_token (parser->lexer)->location;
+ location_t body_loc_after_labels = UNKNOWN_LOCATION;
token_indent_info body_tinfo
= get_token_indent_info (cp_lexer_peek_token (parser->lexer));
@@ -12297,7 +12303,8 @@ cp_parser_implicitly_scoped_statement (cp_parser*
parser, bool *if_p,
/* Create a compound-statement. */
statement = begin_compound_stmt (0);
/* Parse the dependent-statement. */
- cp_parser_statement (parser, NULL_TREE, false, if_p, chain);
+ cp_parser_statement (parser, NULL_TREE, false, if_p, chain,
+ &body_loc_after_labels);
/* Finish the dummy compound-statement. */
finish_compound_stmt (statement);
}
@@ -12306,6 +12313,11 @@ cp_parser_implicitly_scoped_statement (cp_parser*
parser, bool *if_p,
= get_token_indent_info (cp_lexer_peek_token (parser->lexer));
warn_for_misleading_indentation (guard_tinfo, body_tinfo, next_tinfo);
+ if (body_loc_after_labels != UNKNOWN_LOCATION
+ && next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (body_loc_after_labels, next_tinfo.location,
+ guard_tinfo.location, guard_tinfo.keyword);
+
/* Return the statement. */
return statement;
}
@@ -12324,11 +12336,18 @@ cp_parser_already_scoped_statement (cp_parser*
parser, bool *if_p,
{
token_indent_info body_tinfo
= get_token_indent_info (cp_lexer_peek_token (parser->lexer));
+ location_t loc_after_labels;
- cp_parser_statement (parser, NULL_TREE, false, if_p);
+ cp_parser_statement (parser, NULL_TREE, false, if_p, NULL,
+ &loc_after_labels);
token_indent_info next_tinfo
= get_token_indent_info (cp_lexer_peek_token (parser->lexer));
warn_for_misleading_indentation (guard_tinfo, body_tinfo, next_tinfo);
+
+ if (next_tinfo.type != CPP_SEMICOLON)
+ warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
+ guard_tinfo.location,
+ guard_tinfo.keyword);
}
else
{
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index 5d41649..ec59682 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -293,7 +293,7 @@ Objective-C and Objective-C++ Dialects}.
-Wmain -Wmaybe-uninitialized -Wmemset-elt-size -Wmemset-transposed-args @gol
-Wmisleading-indentation -Wmissing-braces @gol
-Wmissing-field-initializers -Wmissing-include-dirs @gol
--Wno-multichar -Wnonnull -Wnonnull-compare @gol
+-Wno-multichar -Wmultistatement-macros -Wnonnull -Wnonnull-compare @gol
-Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} @gol
-Wnull-dereference -Wodr -Wno-overflow -Wopenmp-simd @gol
-Woverride-init-side-effects -Woverlength-strings @gol
@@ -3824,6 +3824,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect
Options}.
-Wmemset-transposed-args @gol
-Wmisleading-indentation @r{(only for C/C++)} @gol
-Wmissing-braces @r{(only for C/ObjC)} @gol
+-Wmultistatement-macros @gol
-Wnarrowing @r{(only for C++)} @gol
-Wnonnull @gol
-Wnonnull-compare @gol
@@ -4496,6 +4497,32 @@ This warning is enabled by @option{-Wall}.
@opindex Wno-missing-include-dirs
Warn if a user-supplied include directory does not exist.
+@item -Wmultistatement-macros
+@opindex Wmultistatement-macros
+@opindex Wno-multistatement-macros
+Warn about unsafe multiple statement macros that appear to be guarded
+by a clause such as @code{if}, @code{else}, @code{for}, @code{switch}, or
+@code{while}, in which only the first statement is actually guarded after
+the macro is expanded.
+
+For example:
+
+@smallexample
+#define DOIT x++; y++
+if (c)
+ DOIT;
+@end smallexample
+
+will increment @code{y} unconditionally, not just when @code{c} holds.
+The can usually be fixed by wrapping the macro in a do-while loop:
+@smallexample
+#define DOIT do @{ x++; y++; @} while (0)
+if (c)
+ DOIT;
+@end smallexample
+
+This warning is enabled by @option{-Wall} in C and C++.
+
@item -Wparentheses
@opindex Wparentheses
@opindex Wno-parentheses
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-1.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-1.c
index e69de29..cdecbb4 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-1.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-1.c
@@ -0,0 +1,118 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(X, Y) \
+ tmp = X; /* { dg-warning "macro expands to multiple statements" } */ \
+ X = Y; \
+ Y = tmp
+
+#define STUFF \
+ if (0) x = y
+
+#define STUFF2 \
+ if (0) x = y; x++
+
+#define STUFF3 \
+ if (x) /* { dg-message "not guarded by this 'if' clause" } */ \
+ SWAP(x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define SET(X, Y) \
+ (X) = (Y)
+
+#define STUFF4 \
+ if (x) \
+ SET(x, y); \
+ SET(x, y)
+
+#define STUFF5 \
+ { tmp = x; x = y; }
+
+#define STUFF6 \
+ x++;;
+
+int x, y, tmp;
+
+void
+fn1 (void)
+{
+ if (x) /* { dg-message "not guarded by this 'if' clause" } */
+ SWAP(x, y); /* { dg-message "in expansion of macro .SWAP." } */
+}
+
+void
+fn2 (void)
+{
+ SWAP(x, y);
+}
+
+void
+fn3 (void)
+{
+ if (x)
+ {
+ SWAP(x, y);
+ }
+}
+
+void
+fn4 (void)
+{
+ if (x)
+ ({ x = 10; x++; });
+}
+
+void
+fn5 (void)
+{
+ if (x) /* { dg-message "not guarded by this 'if' clause" } */
+L1:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+ goto L1;
+}
+
+void
+fn6 (void)
+{
+ if (x)
+ SET (x, y);
+ SET (tmp, x);
+}
+
+void
+fn7 (void)
+{
+ STUFF;
+}
+
+void
+fn8 (void)
+{
+ STUFF2;
+}
+
+void
+fn9 (void)
+{
+ STUFF3; /* { dg-message "in expansion of macro .STUFF3." } */
+}
+
+void
+fn10 (void)
+{
+ STUFF4;
+}
+
+void
+fn11 (void)
+{
+ if (x)
+ STUFF5;
+}
+
+void
+fn12 (void)
+{
+ if (x)
+ STUFF6;
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-10.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-10.c
index e69de29..766ed25 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-10.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-10.c
@@ -0,0 +1,82 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(x, y) \
+ tmp = x; /* { dg-warning "macro expands to multiple statements" } */ \
+ x = y; \
+ y = tmp
+
+#define M1 \
+ switch (x) /* { dg-message "not guarded by this 'switch' clause" } */ \
+ case 1: \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define M2 \
+ switch (x) \
+ case 1: \
+ x++
+
+#define M3 \
+ switch (x) \
+ case 1: \
+ x++;;
+
+#define M4 \
+ switch (x) /* { dg-message "not guarded by this 'switch' clause" } */ \
+L1: \
+ case 1: \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define INC \
+ x++;;
+
+int x, y, tmp;
+
+void
+fn0 (void)
+{
+ switch (x) /* { dg-message "not guarded by this 'switch' clause" } */
+ case 1:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+
+ switch (x) /* { dg-message "not guarded by this 'switch' clause" } */
+ case 1:
+ case 2:
+ case 3:
+ case 4:
+ case 5:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+}
+
+void
+fn1 (void)
+{
+ M1; /* { dg-message "in expansion of macro .M1." } */
+ M2;
+ M3;
+ M4; /* { dg-message "in expansion of macro .M4." } */
+ goto L1;
+}
+
+void
+fn2 (void)
+{
+ switch (x)
+ case 1:
+ INC
+
+ switch (x)
+ case 1:
+ ({ x = 10; x++; });
+}
+
+void
+fn3 (void)
+{
+ switch (x)
+ {
+ case 1:
+ SWAP (x, y);
+ }
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-11.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-11.c
index e69de29..4f4a123 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-11.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-11.c
@@ -0,0 +1,19 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+enum E { A, B };
+
+const char *
+foo (enum E e)
+{
+#define CASE(X) case X: return #X
+ switch (e)
+ {
+ CASE (A);
+ CASE (B);
+ default:
+ return "<unknown>";
+ }
+#undef CASE
+};
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-2.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-2.c
index e69de29..9fef901 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-2.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-2.c
@@ -0,0 +1,137 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(X, Y) \
+ tmp = X; /* { dg-warning "macro expands to multiple statements" } */ \
+ X = Y; \
+ Y = tmp
+
+#define STUFF \
+ if (0) {} else x = y
+
+#define STUFF2 \
+ if (0) {} else x = y; x++
+
+#define STUFF3 \
+ if (x) \
+ {} \
+ else /* { dg-message "not guarded by this 'else' clause" } */ \
+ SWAP(x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define SET(X, Y) \
+ (X) = (Y)
+
+#define STUFF4 \
+ if (x) \
+ {} \
+ else \
+ SET(x, y); \
+ SET(x, y)
+
+#define STUFF5 \
+ { tmp = x; x = y; }
+
+#define STUFF6 \
+ x++;;
+
+int x, y, tmp;
+
+void
+fn1 (void)
+{
+ if (x)
+ {
+ }
+ else /* { dg-message "not guarded by this 'else' clause" } */
+ SWAP(x, y); /* { dg-message "in expansion of macro .SWAP." } */
+}
+
+void
+fn2 (void)
+{
+ SWAP(x, y);
+}
+
+void
+fn3 (void)
+{
+ if (x)
+ {
+ }
+ else
+ {
+ SWAP(x, y);
+ }
+}
+
+void
+fn4 (void)
+{
+ if (x)
+ {
+ }
+ else
+ ({ x = 10; x++; });
+}
+
+void
+fn5 (void)
+{
+ if (x)
+ {
+ }
+ else /* { dg-message "not guarded by this 'else' clause" } */
+L1:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+ goto L1;
+}
+
+void
+fn6 (void)
+{
+ if (x)
+ {
+ }
+ else
+ SET (x, y);
+ SET (tmp, x);
+}
+
+void
+fn7 (void)
+{
+ STUFF;
+}
+
+void
+fn8 (void)
+{
+ STUFF2;
+}
+
+void
+fn9 (void)
+{
+ STUFF3; /* { dg-message "in expansion of macro .STUFF3." } */
+}
+
+void
+fn10 (void)
+{
+ STUFF4;
+}
+
+void
+fn11 (void)
+{
+ if (x)
+ STUFF5;
+}
+
+void
+fn12 (void)
+{
+ if (x)
+ STUFF6;
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-3.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-3.c
index e69de29..d130a35 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-3.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-3.c
@@ -0,0 +1,12 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define CHECK(X) if (!(X)) __builtin_abort ()
+
+void
+fn (int i)
+{
+ CHECK (i == 1);
+ CHECK (i == 2);
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-4.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-4.c
index e69de29..e5cc9c3 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-4.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-4.c
@@ -0,0 +1,14 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define FN(C) \
+ void \
+ fn (void) \
+ { \
+ C; \
+ }
+
+int i;
+
+FN (if (i) ++i)
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-5.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-5.c
index e69de29..0ac84f5 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-5.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-5.c
@@ -0,0 +1,18 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define M(N) \
+L ## N: \
+ x++; x++ /* { dg-warning "macro expands to multiple statements" } */
+
+int x, y, tmp;
+
+void
+fn1 (void)
+{
+ if (x) /* { dg-message "not guarded by this 'if' clause" } */
+ M (0); /* { dg-message "in expansion of macro .M." } */
+ if (x) /* { dg-message "not guarded by this 'if' clause" } */
+ M (1); /* { dg-message "in expansion of macro .M." } */
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-6.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-6.c
index e69de29..5ec9cd9 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-6.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-6.c
@@ -0,0 +1,22 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define M \
+ if (x) x++; x++
+
+void
+f (int x)
+{
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+ M;
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-7.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-7.c
index e69de29..d661f14 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-7.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-7.c
@@ -0,0 +1,18 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(X, Y) \
+ tmp = X; /* { dg-warning "macro expands to multiple statements" } */ \
+ X = Y; \
+ Y = tmp
+
+#define BODY_AND_IF(COND, X, Y) \
+ if (COND) SWAP (X, Y) /* { dg-message "in expansion of macro .SWAP." } */
+
+void
+fn (int x, int y)
+{
+ int tmp;
+ BODY_AND_IF (1, x, y); /* { dg-message "in expansion of macro .BODY_AND_IF."
} */
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-8.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-8.c
index e69de29..06522a7 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-8.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-8.c
@@ -0,0 +1,64 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(x, y) \
+ tmp = x; /* { dg-warning "macro expands to multiple statements" } */ \
+ x = y; \
+ y = tmp
+
+#define M1 \
+ for (i = 0; i < 1; ++i) /* { dg-message "not guarded by this 'for' clause" }
*/ \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define M2 \
+ for (i = 0; i < 1; ++i) \
+ x++
+
+#define M3 \
+ for (i = 0; i < 1; ++i) \
+ x++;;
+
+#define M4 \
+ for (i = 0; i < 1; ++i) /* { dg-message "not guarded by this 'for' clause" }
*/ \
+L1: \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define INC \
+ x++;;
+
+int x, y, tmp;
+
+void
+fn0 (void)
+{
+ int i;
+ for (i = 0; i < 1; ++i) /* { dg-message "not guarded by this 'for' clause" }
*/
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+
+ for (i = 0; i < 1; ++i) /* { dg-message "not guarded by this 'for' clause" }
*/
+L:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+ goto L;
+}
+
+void
+fn1 (void)
+{
+ int i;
+ M1; /* { dg-message "in expansion of macro .M1." } */
+ M2;
+ M3;
+ M4; /* { dg-message "in expansion of macro .M4." } */
+ goto L1;
+}
+
+void
+fn2 (void)
+{
+ for (int i = 0; i < 1; ++i)
+ INC
+
+ for (int i = 0; i < 1; ++i)
+ ({ x = 10; x++; });
+}
diff --git gcc/testsuite/c-c++-common/Wmultistatement-macros-9.c
gcc/testsuite/c-c++-common/Wmultistatement-macros-9.c
index e69de29..350c4f9f 100644
--- gcc/testsuite/c-c++-common/Wmultistatement-macros-9.c
+++ gcc/testsuite/c-c++-common/Wmultistatement-macros-9.c
@@ -0,0 +1,62 @@
+/* PR c/80116 */
+/* { dg-options "-Wmultistatement-macros" } */
+/* { dg-do compile } */
+
+#define SWAP(x, y) \
+ tmp = x; /* { dg-warning "macro expands to multiple statements" } */ \
+ x = y; \
+ y = tmp
+
+#define M1 \
+ while (x) /* { dg-message "not guarded by this 'while' claus" } */ \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define M2 \
+ while (x) \
+ x++
+
+#define M3 \
+ while (x) \
+ x++;;
+
+#define M4 \
+ while (x) /* { dg-message "not guarded by this 'while' claus" } */ \
+L1: \
+ SWAP (x, y) /* { dg-message "in expansion of macro .SWAP." } */
+
+#define INC \
+ x++;;
+
+int x, y, tmp;
+
+void
+fn0 (void)
+{
+ while (x) /* { dg-message "not guarded by this 'while' claus" } */
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+
+ while (x) /* { dg-message "not guarded by this 'while' claus" } */
+L:
+ SWAP (x, y); /* { dg-message "in expansion of macro .SWAP." } */
+ goto L;
+}
+
+void
+fn1 (void)
+{
+ M1; /* { dg-message "in expansion of macro .M1." } */
+ M2;
+ M3;
+ M4; /* { dg-message "in expansion of macro .M4." } */
+ goto L1;
+}
+
+void
+fn2 (void)
+{
+ while (x)
+ INC
+
+ while (x)
+ ({ x = 10; x++; });
+}
Marek
