Bug 36320 - Required diagnosis of syntax error missed
Summary: Required diagnosis of syntax error missed
Status: RESOLVED FIXED
Alias: None
Product: gcc
Classification: Unclassified
Component: preprocessor (show other bugs)
Version: 4.1.3
: P3 normal
Target Milestone: 4.4.0
Assignee: Tom Tromey
URL:
Keywords:
Depends on: 36453
Blocks:
  Show dependency tree / graph
 
Reported: 2008-05-24 10:55 UTC by Neil Booth
Modified: 2008-06-06 20:03 UTC (History)
2 users (show)

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Known to work:
Known to fail:
Last reconfirmed: 2008-05-24 18:04:32

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Description Neil Booth 2008-05-24 10:55:37 UTC 
The syntax error in #elif below is not diagnosed with (say) --std=c99 -pedantic-errors.

int z;
#if 1
#elif
#endif

Syntax is:

elif-group:
        # elif constant-expression new-line groupopt

and constant expression cannot be empty.  The syntax relaxation of 6.10p4 does not apply as the group that the #elif lies in (beginning with the #if) is not skipped.
Comment 1 Tom Tromey 2008-05-24 16:21:05 UTC 
Confirmed.  This seems like a weird design to me, but my reading of the
standard text agrees with yours.
Comment 2 Tom Tromey 2008-05-24 18:04:32 UTC 
Testing a patch.
Comment 3 Tom Tromey 2008-05-30 14:25:55 UTC 
Subject: Bug 36320

Author: tromey
Date: Fri May 30 14:25:09 2008
New Revision: 136209

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=136209
Log:
gcc/testsuite
	PR preprocessor/36320:
	* gcc.dg/cpp/pr36320.c: New file.
libcpp
	PR preprocessor/36320:
	* internal.h (_cpp_parse_expr): Update.
	* expr.c (_cpp_parse_expr): Add 'is_if' argument.  Update error
	messages.
	* directives.c (do_if): Update.
	(do_elif): Require expression if processing group.

Added:
    trunk/gcc/testsuite/gcc.dg/cpp/pr36320.c
Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/libcpp/ChangeLog
    trunk/libcpp/directives.c
    trunk/libcpp/expr.c
    trunk/libcpp/internal.h
Comment 4 Tom Tromey 2008-05-30 15:07:04 UTC 
Fixed on trunk.