honor --declaredLocs in more places, including type mismatch errors; also show kind with --declaredLocs

[timotheecour]

followup after #15666

• honor --declaredLocs in more places, including type mismatch errors, see example 1
• show (humanized) symbol kind in declared in message, which helps with cryptic errors, see example 2

example 1

block:
  type Foo = ref object
  type Foo2 = object
  type Bar[T]=object
  var b: Bar[float]
  b = Foo()

before PR:

t11164.nim(77, 10) Error: type mismatch: got <Foo> but expected 'Bar[system.float]'
    b = Foo()

after PR, when passing --declaredLocs --listfullpaths:off:

t11164.nim(77, 10) Error: type mismatch: got <Foo> [ref declared in t11164.nim(73, 8)] but expected 'Bar[system.float]' [object declared in t11164.nim(75, 8)]
    b = Foo()

example 2

block:
  type Foo = object
  proc fun(a: ref) = discard
  fun(Foo())

before PR:

t11164.nim(43, 6) Error: type mismatch: got <Foo>
but expected one of:
proc fun(a: ref)
  first type mismatch at position: 1
  required type for a: ref
  but expression 'Foo()' is of type: Foo

=> cryptic, the error doesn't tell you why Foo doesn't match unless you know that Foo is of kind object instead of ref
This is a common problem in my experience.

after PR, when passing --declaredLocs --listfullpaths:off:

t11164.nim(43, 6) Error: type mismatch: got <Foo>
but expected one of:
proc fun(a: ref) [proc declared in t11164.nim(42, 8)]
  first type mismatch at position: 1
  required type for a: ref [builtInTypeClass declared in t11164.nim(42, 12)]
  but expression 'Foo()' is of type: Foo [object declared in t11164.nim(39, 8)]

=> now you have all the context to understand the mismatch: fun expects a ref, but Foo is of kind object

future work

• we should also honor --declaredLocs for cannot instantiate errors:

block:
  type Foo[T:ref] = ref object
  type Bar = object
  type Foo1 = Foo[Bar]

currently still gives

t11164.nim(29, 18) Error: cannot instantiate Foo
got: <type Bar>
but expected: <T: ref>
    type Foo1 = Foo[Bar]

which has same drawback of lacking sufficient context to understand the error (especially in complicated cases)

=> #17745

[alaviss]

I think it's a bit too long here. We can certainly borrow a page from C/C++ compilers and print the declaration as a separated hint, which would be much easier to read.

[timotheecour]

how about I change:

t11164.nim(77, 10) Error: type mismatch: got <Foo> [ref declared in t11164.nim(73, 8)] but expected 'Bar[system.float]' [object declared in t11164.nim(75, 8)]

to

t11164.nim(77, 10) Error: type mismatch: got <Foo> [ref declared in t11164.nim(73, 8)]
  but expected 'Bar[system.float]' [object declared in t11164.nim(75, 8)]

with --declaredLocs:on; and keep the old formatting without newline with --declaredLocs:off

this will be consistent with sigmatch error formatting (got on 1 line, candidates on subsequent lines)

[Araq]

If you spend more time on it, do it properly. The problem is an error message like

"expected AbsoluteFile but got AbsoluteFile (= distinct string)"

which is caused by different modules that both export AbsoluteFile which is caused by --path issues. So add some logic to make the error message better for "expected X but got X", there is no need for yet another compiler switch that nobody knows about...

[timotheecour]

@Araq PTAL

I think it's a bit too long here. We can certainly borrow a page from C/C++ compilers and print the declaration as a separated hint, which would be much easier to read.

improved formatting, should now read well whether or not declaration locations are shown

add some logic to make the error message better for "expected X but got X"

done, the declaration locations are now shown when either the names clash or when --declaredlocs is provided

example

• with name clash:

t11164.nim(114, 10) Error: type mismatch:
 got <Foo> [object declared in t11164.nim(112, 8)]
 but expected 'Foo = object' [object declared in t11164b.nim(2, 8)]

• without name clash:

t11164.nim(120, 10) Error: type mismatch: got <Foo> but expected 'Foo2 = object'

• without name clash but with --declaredlocs (consistent with add --declaredlocs to show symbol declaration location in message #15666)

t11164.nim(120, 10) Error: type mismatch:
 got <Foo> [object declared in t11164.nim(118, 8)]
 but expected 'Foo2 = object' [object declared in t11164b.nim(6, 8)]

(all above with --listfullpaths:off)