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digitalmars.D.learn - Problem with public example in Phobos

reply berni44 <dlang d-ecke.de> writes:
I thought it's a fast fix, just adding some documentation and a 
unittest. But when running the style checker I got into trouble. 
A shortend version of the problem:

I added the following public unittest to writeUpToNextSpec in 
std.format:

     ///
      safe unittest
     {
         import std.array;
         auto w = appender!(char[])();

         auto f = FormatSpec("input: %10d output: %s");
         assert(f.writeUpToNextSpec(w) == true);

         assert(w.data == "input: ");
         assert(f.spec == 'd');
         assert(f.width == 10);

         // [...]
     }

While it works with the normal unittest test routines (make -f 
posix.mak unittest) the stylechecker complains (make -f posix.mak 
style).

I meanwhile found out, that I have to add the template parameter 
dchar to FormatSpec, although I don't understand why. (I know, 
that these tests should work, when they are put into a separate 
file. But I do not understand why the original version doesn't 
work there.)

But more problematic: When I add this templete parameter, I still 
get an error from the style checker, this time it's a linker 
problem, and I'm completely lost here. The error does not occure 
when checking std.format, but when checking std.package:

parsing std/package.d
/usr/bin/ld: std_package.o: in function 
`_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv':
__main.d:(.text._D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv[_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_
11_1FNaNfZv]+0x17): undefined reference to
`_D3std6format__T10FormatSpecTwZQp6__initZ'
/usr/bin/ld: 
__main.d:(.text._D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv[_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_
11_1FNaNfZv]+0x38): undefined reference to
`_D3std6format__T10FormatSpecTwZQp6__ctorMFNaNbNcNiNfxAwZSQCdQCc__TQByTwZQCe'
/usr/bin/ld: std_package.o: in function 
`_D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFNaNlNfKQBpZb':
__main.d:(.text._D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFNaNlNfKQBpZb[_D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFN
NlNfKQBpZb]+0x15a): undefined reference to
`_D3std6format__T10FormatSpecTwZQp6fillUpMFNaNlNfZv'


What do I miss?
Dec 18 2019
parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On 12/18/19 3:56 AM, berni44 wrote:

 I thought it's a fast fix, just adding some documentation and a 
 unittest. But when running the style checker I got into trouble. A 
 shortend version of the problem:
 
 I added the following public unittest to writeUpToNextSpec in std.format:
 
      ///
       safe unittest
      {
          import std.array;
          auto w = appender!(char[])();
 
          auto f = FormatSpec("input: %10d output: %s");
          assert(f.writeUpToNextSpec(w) == true);
 
          assert(w.data == "input: ");
          assert(f.spec == 'd');
          assert(f.width == 10);
 
          // [...]
      }
 
 While it works with the normal unittest test routines (make -f posix.mak 
 unittest) the stylechecker complains (make -f posix.mak style).


style checker has nothing to do with buildable code. It just enforces 
the style follows the guidelines.

Just look at the output and see what it's asking you to do.


 
 I meanwhile found out, that I have to add the template parameter dchar 
 to FormatSpec, although I don't understand why. (I know, that these 
 tests should work, when they are put into a separate file. But I do not 
 understand why the original version doesn't work there.)


OK, so writeUpToNextSpec is a method inside a templated struct 
(FormatSpec). *Inside* any templated struct (or template of any kind 
really), the name of the template is synonymous with the *instantiated* 
template.

e.g.:

struct S(T)
{
    S *ptr;
}

static assert(is(typeof(S!int.ptr) == S!int *));

But when the code is copied *outside* the template, it needs the full 
instantiation.

This comes from the fact that unless you are declaring a template with 
`template`, you are using the eponymous template trick under the hood.

That is:

struct S(T)
{
}

is short for:

template S(T)
{
    struct S
    {
    }
}

where naturally the S inside the template is not the template but the 
struct.

In the case of a documented unittest, I think the CI is trying to make 
sure the test can run on its own.

Note, putting unittests inside templates duplicates the unit test for 
every instantiation. Using an instantiation other than the template 
itself is going to result in a lot of duplicated tests. Unfortunately, 
there is no mechanism to have a documented unittest that isn't part of 
the instantiation.


 
 But more problematic: When I add this templete parameter, I still get an 
 error from the style checker, this time it's a linker problem, and I'm 
 completely lost here. The error does not occure when checking 
 std.format, but when checking std.package:
 
 parsing std/package.d
 /usr/bin/ld: std_package.o: in function 
 `_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv':
 __main.d:(.text._D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv[_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_
11_1FNaNfZv]+0x17): 
 undefined reference to `_D3std6format__T10FormatSpecTwZQp6__initZ'
 /usr/bin/ld: 
 __main.d:(.text._D3std6format__T10FormatSpecTaZQp22__unittest_L1237_C11_1FNaNfZv[_D3std6format__T10FormatSpecTaZQp22__unittest_L1237_
11_1FNaNfZv]+0x38): 
 undefined reference to 
 `_D3std6format__T10FormatSpecTwZQp6__ctorMFNaNbNcNiNfxAwZSQCdQCc__TQByTwZQCe' 
 
 /usr/bin/ld: std_package.o: in function 
 `_D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQn
QBxMFNaNlNfKQBpZb': 
 
 __main.d:(.text._D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFNaNlNfKQBpZb[_D3std6format__T10FormatSpecTwZQp__T17writeUpToNextSpecTSQCd5array__T8AppenderTAaZQnZQBxMFN
NlNfKQBpZb]+0x15a): 
 undefined reference to `_D3std6format__T10FormatSpecTwZQp6fillUpMFNaNlNfZv'


This might be a bug. I don't know how this is built, so I'm not sure. 
But it looks like the compiler isn't including some instantiation of 
FormatSpec when linking.

-Steve
Dec 18 2019
parent reply berni44 <dlang d-ecke.de> writes:
On Wednesday, 18 December 2019 at 17:57:15 UTC, Steven 
Schveighoffer wrote:

 style checker has nothing to do with buildable code. It just 
 enforces the style follows the guidelines.


It also checks, that the public unittests can be used on it's 
own. (Target publictests in the makefile. Didn't know that too 
until yesterday.)


 This comes from the fact that unless you are declaring a 
 template with `template`, you are using the eponymous template 
 trick under the hood.


Aaaah. It's so common, that one forgets about it. Thanks for 
reminding. :-)


 Note, putting unittests inside templates duplicates the unit 
 test for every
 instantiation. Using an instantiation other than the template 
 itself is going
 to result in a lot of duplicated tests. Unfortunately, there is 
 no mechanism to have a documented unittest that isn't part of 
 the instantiation.


I know about that problem. Would be good, to have some such 
mechanism. Until we have, I'll resort to moving them after the 
template and adding a link to the docs, see below.


 This might be a bug. I don't know how this is built, so I'm not 
 sure. But it looks like the compiler isn't including some 
 instantiation of FormatSpec when linking.


I moved the unittest outside the template, just to find out, that 
there is allready one, which is almost identical. I merged the 
two and added a link to the docs, so people can find the example.

Thanks a lot!
Dec 18 2019
parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Wed, Dec 18, 2019 at 07:16:15PM +0000, berni44 via Digitalmars-d-learn wrote:

 On Wednesday, 18 December 2019 at 17:57:15 UTC, Steven Schveighoffer wrote:


[...]

 Note, putting unittests inside templates duplicates the unit test
 for every instantiation. Using an instantiation other than the
 template itself is going to result in a lot of duplicated tests.
 Unfortunately, there is no mechanism to have a documented unittest
 that isn't part of the instantiation.


 
 I know about that problem. Would be good, to have some such mechanism.
 Until we have, I'll resort to moving them after the template and
 adding a link to the docs, see below.


[...]

Hackish workaround:

	struct TemplateStruct(T) {
		auto foo(...) { ... }

		static if (is(T == int))
			/// Look, ma! I'm documented!
			unittest {
			}
	}

	// Make sure the test actually runs
	version(unittest) alias dummy = TemplateStruct!int;


T

-- 
Why can't you just be a nonconformist like everyone else? -- YHL
Dec 18 2019