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From: "haoxintu at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95725] New: Confusing error diagnostic in an invalid template
Date: Wed, 17 Jun 2020 17:02:40 +0000	[thread overview]
Message-ID: <bug-95725-4@http.gcc.gnu.org/bugzilla/> (raw)

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95725

            Bug ID: 95725
           Summary: Confusing error diagnostic in an invalid template
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

This code test.cc, makes GCC get confused while parsing.

$cat test.cc
template <decltype(= ;


$g++-trunk -w -c test.cc
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:22: error: expected ‘>’ before ‘;’ token
test.cc:1:22: error: expected unqualified-id before ‘;’ token


$g++-10 -w -c test.cc
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:21: error: expected ‘)’ before ‘;’ token
    1 | template <decltype(= ;
      |                   ~ ^~
      |                     )
test.cc:1:22: error: expected ‘>’ before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:22: error: expected unqualified-id before ‘;’ token


$g++-9 -w -c test.cc
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:21: error: expected ‘)’ before ‘;’ token
    1 | template <decltype(= ;
      |                   ~ ^~
      |                     )
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:11: error: expected identifier before ‘decltype’
    1 | template <decltype(= ;
      |           ^~~~~~~~
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:21: error: expected ‘)’ before ‘;’ token
    1 | template <decltype(= ;
      |                   ~ ^~
      |                     )
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:20: error: expected primary-expression before ‘=’ token
    1 | template <decltype(= ;
      |                    ^
test.cc:1:22: error: expected primary-expression before ‘;’ token
    1 | template <decltype(= ;
      |                      ^
test.cc:1:11: error: expected ‘>’ before ‘decltype’
    1 | template <decltype(= ;
      |           ^~~~~~~~
test.cc:1:22: error: expected unqualified-id before ‘;’ token
    1 | template <decltype(= ;
      |                      ^

My GCC versions are:

$g++-trunk --version
g++ (GCC) 11.0.0 20200526 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$g++-10 --version
g++-10 (Ubuntu 10.1.0-2ubuntu1~18.04) 10.1.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$g++-9 --version
g++-9 (Ubuntu 9.3.0-11ubuntu0~18.04.1) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

In conclusion, GCC might have two issues in parsing this code:
1. GCC-trunk misses "error: expected ‘)’ before ‘;’ token" message
2. GCC-9 emits too many duplicated error messages.

             reply	other threads:[~2020-06-17 17:02 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-17 17:02 haoxintu at gmail dot com [this message]
2020-06-17 17:43 ` [Bug c++/95725] " marxin at gcc dot gnu.org
2020-06-17 17:49 ` haoxintu at gmail dot com
2020-06-17 18:58 ` msebor at gcc dot gnu.org
2020-06-17 23:49 ` mpolacek at gcc dot gnu.org
2020-06-17 23:57 ` redi at gcc dot gnu.org
2020-06-18  1:51 ` haoxintu at gmail dot com
2020-06-18  6:23 ` haoxintu at gmail dot com
2020-06-18  8:34 ` rguenth at gcc dot gnu.org
2020-06-18 11:26 ` redi at gcc dot gnu.org
2020-06-18 11:31 ` redi at gcc dot gnu.org
2024-05-09  9:08 ` redi at gcc dot gnu.org

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