[Bug c++/15179] Error message can be improved

[Bug c++/15179] Error message can be improved

[pinskia at gcc dot gnu dot org]

------- Comment #12 from pinskia at gcc dot gnu dot org  2007-02-10 09:17 -------
*** Bug 30754 has been marked as a duplicate of this bug. ***


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |benoit dot hudson at gmail
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] Error message can be improved

[pinskia at gcc dot gnu dot org]

------- Comment #11 from pinskia at gcc dot gnu dot org  2007-02-10 09:16 -------
*** Bug 28182 has been marked as a duplicate of this bug. ***


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |_vi at list dot ru


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] bad parse error recovery with missing typename

[manu at gcc dot gnu dot org]

------- Comment #13 from manu at gcc dot gnu dot org  2008-08-18 17:51 -------
Let's give meaningful short descriptions to the bugs, please.


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manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Error message can be        |bad parse error recovery
                   |improved                    |with missing typename


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] bad parse error recovery with missing typename

[andris dot pavenis at iki dot fi]

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------- Comment #14 from andris dot pavenis at iki dot fi  2008-11-15 09:53 -------
Created an attachment (id=16681)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16681&action=view)
Another C++ example to ilustrate misleading error message about missing
typename keyword

This is a short example where one is getting completely misleeding error
message:

test.cpp:22: error: expected constructor, destructor, or type conversion before
‘&’ token

I had to try to compile this example with Visual C++ to figured out what's the
reason of compiler error was. It reported it more clearly.

Tried:
GNU C++ (GCC) version 4.3.0 20080428 (Red Hat 4.3.0-8) (x86_64-redhat-linux)
GNU C++ version 3.4.6 20060404 (Red Hat 3.4.6-9) (x86_64-redhat-linux)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] bad parse error recovery with missing typename

[manu at gcc dot gnu dot org]

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------- Comment #15 from manu at gcc dot gnu dot org  2009-08-04 09:22 -------
Testcase in comment #9 does not produce any output anymore.

Testcase in comment #10 produces:

/home/manuel/src/pr15179.C:8:18: error: type ‘A<yn>’ is not derived from type
‘B<yn>’
/home/manuel/src/pr15179.C:8:23: error: expected ‘;’ before ‘Type’


Testcase in comment #14 produces:

/home/manuel/src/pr15179-3.C: At global scope:
/home/manuel/src/pr15179-3.C:22:23: error: expected constructor, destructor, or
type conversion before ‘&’ token


It seems to me that there is a tentative parse of a type in
cp_parser_decl_specifier_seq, that fails, and then we end up trying to parse
something else until it fails completely.

For the typedef testcases, the code in cp_parser_decl_specifier_seq could just
directly parse the complete typedef and return, because only a type can follow
typedef.

For the non-typedef testcase, it is less clear how to handle a failure to parse
a type, since that may actually mean we are looking at something else.

I don't really know where the "failure" happens. That would need more debugging
that I have time to do now. Any help appreciated.


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manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |4.4.0
   Last reconfirmed|2005-05-08 17:34:10         |2009-08-04 09:22:11
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] bad parse error recovery with missing typename

[jason at gcc dot gnu dot org]

------- Comment #16 from jason at gcc dot gnu dot org  2009-11-08 04:02 -------


*** This bug has been marked as a duplicate of 15946 ***


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jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] Error message can be improved

[redi at gcc dot gnu dot org]

------- Additional Comments From redi at gcc dot gnu dot org  2004-08-05 11:24 -------
It doesn't need to involve nested classes either:
-----------------------------
template <bool>
struct A {
    typedef int type;
};

template <bool yn>
struct B {
    typedef A<yn>::type Type;
};
-----------------------------
3.4 and mainline give:
bug.cc:8: error: type `A<<anonymous> >' is not derived from type `B<yn>'
bug.cc:8: error: ISO C++ forbids declaration of `type' with no type
bug.cc:8: error: expected `;' before "Type"

Again, the problem is a missing "typename" but you can't guess that from the
diagnostic. Compiling the same code with GCC 3.3 gives the "implicit typename
is deprecated" warning which makes the error much easier to find, therefore I
consider this a regression against 3.3


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] Error message can be improved

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-04-28 00:00 -------
Confirmed. For this code 
----------- 
template <class T> class O { 
    typedef O<T> Type; 
    typedef int inner; 
    class I 
    { 
        typedef Type::inner inner; 
    }; 
}; 
----------- 
gcc produces 
g/x> /home/bangerth/bin/gcc-3.5-pre/bin/c++ -c x.cc 
x.cc:6: error: type `O<T>' is not derived from type `O<T>::I' 
x.cc:6: error: ISO C++ forbids declaration of `inner' with no type 
x.cc:6: error: expected `;' before "inner" 
 
which is indeed confusing. (icc, for reference, simply accepts the code 
even with -Xc -ansi -- which is probably wrong.) 
 
Frankly, I have no clue what path in the compiler we are taking to get 
to this error message... 
 
W. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179

[Bug c++/15179] Error message can be improved

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-04-27 22:56 -------
Lets keep this for the error message, because PR 9634 is the bug which talks about this 
being not a bug but the standard is not clear.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
           Keywords|rejects-valid               |diagnostic
            Summary|[3.4/3.5 Regression] Rejects|Error message can be
                   |typedef of a type of an     |improved
                   |outerclass                  |
   Target Milestone|3.4.1                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15179