http://d.puremagic.com/issues/show_bug.cgi?id=8894

           Summary: 2.059: Lookup error message has become uninformative
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: regression
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrej.mitrovich@gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-25 16:11:17 PDT ---
module test;
struct Foo { }

void main()
{
    Foo f;
    auto x = f.x;
}

2.058:
$ dmd test.d
test.d(6): Error: no property 'x' for type 'Foo'

2.059:
$dmd test.d
test.d(6): Error: undefined identifier 'x'

Best guess: it's probably related to UFCS changes in 2.059.

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--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-25 16:17:19 PDT ---
(In reply to comment #0)
> module test;
> struct Foo { }
> 
> void main()
> {
>     Foo f;
>     auto x = f.x;
> }
> 
> 2.058:
> $ dmd test.d
> test.d(6): Error: no property 'x' for type 'Foo'
> 
> 2.059:
> $dmd test.d
> test.d(6): Error: undefined identifier 'x'
> 
> Best guess: it's probably related to UFCS changes in 2.059.

It seems errors are gagged at this point in "Expression *Type::getProperty(Loc loc, Identifier *ident)" in file mtype.c:

if (this != Type::terror)
{
    assert(global.gag);  // << passes

    if (s)
        error(loc, "no property '%s' for type '%s', did you mean '%s'?",
ident->toChars(), toChars(), s->toChars());
    else
        error(loc, "no property '%s' for type '%s'", ident->toChars(),
toChars());
}

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--- Comment #2 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-25 16:24:25 PDT ---
(In reply to comment #1)
> It seems errors are gagged at this point in "Expression *Type::getProperty(Loc loc, Identifier *ident)" in file mtype.c:

The gagging starts in `DotIdExp::semantic(Scope *sc, int flag)` with a nice
comment:


/* This would be much better if we added a "hasProperty" method to types,
 * i.e. the gagging is a bad way.
 */

// ..

Type *t1 = e1->type;
unsigned errors = global.startGagging();
e = t1->dotExp(sc, e1, ident);
if (global.endGagging(errors))  // if failed to find the property
{
    e1->type = t1;              // kludge to restore type
    e = resolveUFCSProperties(sc, this);
}
e = e->semantic(sc);
return e;

So it seems UFCS really is to blame. Type properties are checked first, then UFCS is checked, however if neither of them have a match then we should print out the property error rather than the UFCS error.

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--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-26 12:35:01 PDT ---
I've been thinking.. maybe we could change the verrorPrint function to print to a buffer by default, and then print that to stdout/stderr from the caller function when gagging is off, but store the error to the global struct if gagging is on. That way we can recover the previous error messages if resolving UFCS failed.

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--- Comment #4 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-10-26 12:39:14 PDT ---
(In reply to comment #3)
> I've been thinking.. maybe we could change the verrorPrint function to print to a buffer by default, and then print that to stdout/stderr from the caller function when gagging is off, but store the error to the global struct if gagging is on. That way we can recover the previous error messages if resolving UFCS failed.

Essentially the code would then look something like this:

Type *t1 = e1->type;
unsigned errors = global.startGagging();
e = t1->dotExp(sc, e1, ident);
OutBuffer oldErrors;  // new
if (global.endGagging(errors, &oldErrors))  // new
{
    e1->type = t1;              // kludge to restore type

    errors = global.startGagging();  // new
    e = resolveUFCSProperties(sc, this);
    if(global.endGagging(errors))  // new
        printErrors(&oldErrors);  // new
}
e = e->semantic(sc);
return e;

"&oldErrors" would be an optional parameter where current errors are stored, as the old errors would be cleared on the call to endGagging.

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--- Comment #5 from Don <clugdbug@yahoo.com.au> 2012-11-09 03:08:43 PST ---
Easy way would be, if errors aren't gagged (so that we care about which error message occurs), to gag the UFCS attempt, and if it fails, make the property call again.

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com


--- Comment #6 from Walter Bright <bugzilla@digitalmars.com> 2012-11-13 22:57:15 PST ---
https://github.com/D-Programming-Language/dmd/pull/1274

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--- Comment #7 from Walter Bright <bugzilla@digitalmars.com> 2012-12-10 04:20:12 PST ---
https://github.com/D-Programming-Language/dmd/pull/1361

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs@eml.cc


--- Comment #8 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2012-12-10 09:06:22 PST ---
*** Issue 9128 has been marked as a duplicate of this issue. ***

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--- Comment #9 from github-bugzilla@puremagic.com 2012-12-10 18:08:28 PST ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/a0a63bbf95ab82ed9e599d1641f7bd9968c7a9bb Fixes Issue 8894 - Regression with property lookup error message.

https://github.com/D-Programming-Language/dmd/commit/bcbffafa02ea119f383f3a26a1d4ceae088ccdde Merge pull request #1361 from AndrejMitrovic/Fix8894_2

Issue 8894 - Regression with property lookup error message.

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