| Summary: | Add a warning to detect empty body of if statements (like in the C frontend) | ||
|---|---|---|---|
| Product: | gcc | Reporter: | jbach1 |
| Component: | c++ | Assignee: | Gabriel Dos Reis <gdr> |
| Status: | RESOLVED FIXED | ||
| Severity: | enhancement | CC: | austern, carlo, gcc-bugs, giovannibajo, mueller, nathan, simon_baldwin |
| Priority: | P3 | Keywords: | diagnostic |
| Version: | 3.4.0 | ||
| Target Milestone: | 4.2.0 | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | 2005-12-11 21:47:29 | |
| Attachments: | updated patch | ||
Fix:
int x=1;
if (x == 0)
{
cout << "x equals zero" << endl;
}
From: Carlo Wood <carlo@alinoe.com> To: jbach1@caramail.com Cc: gcc-gnats@gcc.gnu.org Subject: Re: preprocessor/5520: There's a warning I miss with "if{} else{}" statement Date: Tue, 29 Jan 2002 03:09:21 +0100 On Mon, Jan 28, 2002 at 11:41:20PM -0000, jbach1@caramail.com wrote: > I think a warning shoul be raised when someone writes > if (condition); Only *before* replacing macros please (if at all). Macros can be empty and be used like: if (condition) POSSIBLY_EMPTY_MACRO; -- Carlo Wood <carlo@alinoe.com> State-Changed-From-To: open->analyzed
State-Changed-Why: confirmed. gcc has such a warning.
To address carlo's point. Macros that expand to noexpression, are usually written as '((void)0)'
Responsible-Changed-From-To: unassigned->gdr Responsible-Changed-Why: Diagnostic mantainer *** Bug 19773 has been marked as a duplicate of this bug. *** Subject: Re: Add a warning to detect empty body of if statements
(like in the C frontend)
mueller at kde dot org wrote:
> ------- Comment #5 from mueller at kde dot org 2006-01-05 10:19 -------
> http://gcc.gnu.org/ml/gcc-patches/2005-12/msg01627.html
Could cp_parser_implicitly_scoped_statement be flattened to use
cp_lexer_next_token_is, rather than CLNTI_not? that'd read better. I'd suggest
if(cp_lexer_next_token_is (parser->lexer, CPP_OPEN_BRACE))
.. handle {...}
else if (cp_lexer_next_token_is (parser->lexer (CPP_SEMICOLON))
.. handle empty
else
.. handle implicitly scoped stmt
The C++ changes will be ok with that change. Someone else will need to approve
the C change (but it looks ok to me)
nathan
Created attachment 10596 [details]
updated patch
I agree, that makes it much more readable. updated accordingly and rediffed against current trunk. bootstrapped, regtested successfully.
Subject: Bug 5520 Author: rguenth Date: Fri Jan 20 09:30:22 2006 New Revision: 110019 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=110019 Log: 2006-01-20 Dirk Mueller <dmueller@suse.com> PR c++/5520 * c-parser.c (c_parser_if_body): Use build_empty_stmt() instead of a special NOP marker. * c-typeck.c (c_finish_if_stmt): Remove obsoleted special NOP marker handling. * c-common.h (empty_body_warning): Add forward declaration. * c-common.c (empty_body_warning): Add (from c_finish_if_stmt). Now uses IS_EMPTY_STMT() instead of special NOP markers. * semantics.c (finish_if_stmt): Call empty_body_warning. * parser.c (cp_parser_implicitly_scoped_statement): Mark empty statement with an empty stmt. * g++.dg/warn/empty-body.C: New. Added: trunk/gcc/testsuite/g++.dg/warn/empty-body.C Modified: trunk/gcc/ChangeLog trunk/gcc/c-common.c trunk/gcc/c-common.h trunk/gcc/c-parser.c trunk/gcc/c-typeck.c trunk/gcc/cp/ChangeLog trunk/gcc/cp/parser.c trunk/gcc/cp/semantics.c trunk/gcc/testsuite/ChangeLog Fixed. *** Bug 28992 has been marked as a duplicate of this bug. *** |
I think a warning shoul be raised when someone writes if (condition); { } instead of if (condition) { } (===== Watch at the ";" ====) Actually, it can only be a mistake, and that's a pity it's not detected. It drives to severe bugs. Release: 2.95 -> 3.4 Environment: DOS (DJGPP) How-To-Repeat: int x=1; if (x == 0); { cout << "x equals zero" << endl; }