http://d.puremagic.com/issues/show_bug.cgi?id=4563

           Summary: [module system] Error messages for missing package or
                    missing name
           Product: D
           Version: D1 & D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: diagnostic
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2010-08-01 15:10:25 PDT ---
This is a wrong D2 program ("bitmanips" name doesn't exist):


import std.bitmanips: bitfields;
void main() {}


This is the error message given by dmd 2.047:

test.d(1): Error: module bitmanips is in file 'std\bitmanips.d' which cannot be
read


But a better error message can be:

test.d(1): Error: module 'bitmanips' not found in package 'std'.

---------------------

This is another wrong D2 program (the 'bitfield' name is missing inside
std.bimanip):


import std.bitmanip: bitfield;
void main() {}


This is the error message given by dmd 2.047:

test.d(1): Error: import bitfield not found
test.d(1): Error: alias test.bitfield recursive alias declaration


But the second error message can be omitted, it's useless and quite confusing. So DMD can print just:

test.d(1): Error: import name 'bitfield' not found inside 'std.bitmanip'
module.


See also bug 3845

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Andrej Mitrovic <andrej.mitrovich@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2010-08-01 15:43:08 PDT ---
Agreed. There's an example in the docs (which I've filed a bug report for) that imports std.hiddenfunc which doesn't exist anymore. "File cannot be read" is pretty ambiguous in it's meaning.

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--- Comment #2 from bearophile_hugs@eml.cc 2011-08-10 14:05:55 PDT ---
Giving code to a D newbie such person didn't know what this error message means:


foo.d(3): Error: module ascii is in file 'std/ascii.d' which cannot
be read
import path[0] = /usr/include/d
import path[1] = /usr/include/d/druntime/import


The problem was simple, he has used dmd 2.053 instead of the successive one, so std.ascii was not present yet. This error message is not clear enough.

In a similar situation Python2 gives:
ImportError: No module named foo

I suggest an error message like:

foo.d(3): Error: module "std.ascii" not found (file 'std/ascii.d').

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--- Comment #3 from bearophile_hugs@eml.cc 2011-11-25 16:36:00 PST ---
Now the situation is worse (DMD 2.057head):


import std.math: foo;
void main() {}


Gives:

test.d(1): Error: import __anonymous foo not found
test.d(1): Error: alias test.foo recursive alias declaration

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--- Comment #4 from bearophile_hugs@eml.cc 2012-01-04 03:11:27 PST ---
The situation is not improved.

Wrong D2 code:


import core.stdc.stdlib: puts;
import std.stdio: reverse;
void main() {
    puts("hello");
    int[] a = [1, 2, 3];
    reverse(a);
}



After the recent changes in import semantics DMD 2.058head gives:

test.d(4): Error: undefined identifier puts
test.d(6): Error: undefined identifier reverse

But instead of such errors at the usage point I suggest to give import errors, something like:

test.d(1): Error: name 'puts' not present in 'core.stdc.stdlib' module.
test.d(2): Error: name 'reverse' not present in 'std.stdio' module.

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Leandro Lucarella <leandro.lucarella@sociomantic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |leandro.lucarella@sociomant
                   |                            |ic.com


--- Comment #5 from Leandro Lucarella <leandro.lucarella@sociomantic.com> 2012-01-10 04:40:42 PST ---
*** Issue 7253 has been marked as a duplicate of this issue. ***

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--- Comment #6 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-23 18:53:44 PDT ---
(In reply to comment #0)
> import std.bitmanips;
> void main() {}
> 
> test.d(1): Error: module bitmanips is in file 'std\bitmanips.d' which cannot     be read

This is the only test-case left to fix in this Issue (the others seem to be
fixed).

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--- Comment #7 from bearophile_hugs@eml.cc 2012-10-24 05:09:04 PDT ---
(In reply to comment #6)

> This is the only test-case left to fix in this Issue (the others seem to be
> fixed).

This is the current situation:

----------------

// Case#1
import std.bitmanips: bitfields;
void main() {}

test.d(1): Error: module bitmanips is in file 'std\bitmanips.d' which cannot be
read
import path[0] = C:\dmd2\src\phobos\
import path[1] = C:\dmd2\src\druntime\import\
import path[2] = C:\leonardo\d_bugs\
import path[3] = C:\dmd2\windows\bin\..\..\src\phobos
import path[4] = C:\dmd2\windows\bin\..\..\src\druntime\import

----------------

// Case#2
import std.bitmanip: bitfield;
void main() {}

test.d(1): Error: module std.bitmanip import 'bitfield' not found, did you mean
'template bitfields(T...)'?

----------------

// Case#3
import std.math: foo;
void main() {}

test.d(1): Error: module std.math import 'foo' not found, did you mean
'function fma'?

----------------

The Case#1 probably needs a better error message.

The messages in cases #2 and #3 seem acceptable, it's not bad. But they sub-optimal, in Case#3 this seems better:

test.d(1): Error: name 'foo' not found in module std.math, did you mean
function 'fma'?

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--- Comment #8 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-24 06:48:43 PDT ---
(In reply to comment #7)
> test.d(1): Error: module bitmanips is in file 'std\bitmanips.d' which cannot be
> read
> The Case#1 probably needs a better error message.

Yes, it can be:

test.d(1): Error: module bitmanips not found in package 'std'

However what if the module is not in any package? Example:

import bitmanips; void main() { }

=> test.d(1): Error: module bitmanips is in file 'bitmanips.d' which cannot be
read

What should we do here?

> test.d(1): Error: name 'foo' not found in module std.math, did you mean
> function 'fma'?

I would replace 'name' with 'symbol' here.

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--- Comment #9 from bearophile_hugs@eml.cc 2012-10-24 10:13:27 PDT ---
(In reply to comment #8)

> However what if the module is not in any package? Example:
> 
> import bitmanips; void main() { }
> 
> => test.d(1): Error: module bitmanips is in file 'bitmanips.d' which cannot be
> read
> 
> What should we do here?

Instead of writing:

test.d(1): Error: module bitmanips cannot be found in package 'std'.

It omits the last part of the message:

test.d(1): Error: module bitmanips cannot be found.

(Unrelated: do you know why D error messages don't have an ending full stop "." as in correct English?)

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