preprocessor/2706: #defines expanded when -fpreprocessed given

[nathan at codesourcery dot com]

>Number:         2706
>Category:       preprocessor
>Synopsis:       #defines expanded when -fpreprocessed given
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          accepts-illegal
>Submitter-Id:   net
>Arrival-Date:   Tue May 01 06:46:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Nathan
>Release:        1May2001 CVS 3.1 and 3.0
>Organization:
>Environment:

>Description:
the attached source is ill-formed, however it is accepted
as cpp appears to expand HASH to # and then process
the resultant #define. To make things more confusing 
when rereading the preprocessed source , the #defines are
again expanded. This is a 2.95 regression and will be
a real headache to anybody trying to track down obsucre
preprocessor related problems in their source!

There appear to be 3 bugs, but could all have the same
cause.
1) a line is macro expanded and the result interpretted
for preprocessor directives
2) no diagnostic is issued for finding something like
#define in a preprocessed source
3) macros are expanded in preprocessed source.

current tree gives, 
nathan@uha:275>./g++ -B ./ -save-temps current/cpp.C -c
nathan@uha:276>more cpp.ii                             
# 2 "current/cpp.C"
# define X "string"
# include "thing"

char const *foo ()
{
    return X;
}
nathan@uha:277>./cc1plus -fpreprocessed cpp.ii -quiet  

2.95 says
nathan@uha:278>g++ -save-temps current/cpp.C -c
current/cpp.C:3: undefined or invalid # directive
current/cpp.C: In function `const char * foo()':
current/cpp.C:7: `X' undeclared (first use this function)
current/cpp.C:7: (Each undeclared identifier is reported only once
current/cpp.C:7: for each function it appears in.)
current/cpp.C:8: warning: control reaches end of non-void function `foo()'
nathan@uha:279>more cpp.ii
# 1 "current/cpp.C"

#  define X "string"
#  include "thing"

char const *foo ()
{
    return X;
}
nathan@uha:280>g++ cpp.ii -c 
current/cpp.C:3: undefined or invalid # directive
current/cpp.C: In function `const char * foo()':
current/cpp.C:7: `X' undeclared (first use this function)
current/cpp.C:7: (Each undeclared identifier is reported only once
current/cpp.C:7: for each function it appears in.)
current/cpp.C:8: warning: control reaches end of non-void function `foo()'

>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="cpp.C"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="cpp.C"

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