test removing dollar for objects out of system (#20242)

* test removing dollar for objects out of system

* test & fixes

* fix bootstrap

* use nimPreviewSlimSystem, test stdlib category

* fix test

1 files changed, 39 insertions, 0 deletions

diff --git a/lib/std/private/miscdollars.nim b/lib/std/private/miscdollars.nim
index 840fedf54..47b788ee9 100644
--- a/lib/std/private/miscdollars.nim
+++ b/lib/std/private/miscdollars.nim
@@ -12,3 +12,42 @@ template toLocation*(result: var string, file: string | cstring, line: int, col:
       result.add ", "
       addInt(result, col)
     result.add ")"
+
+when defined(nimHasIsNamedTuple):
+  proc isNamedTuple(T: typedesc): bool {.magic: "TypeTrait".}
+else:
+  # for bootstrap; remove after release 1.2
+  proc isNamedTuple(T: typedesc): bool =
+    # Taken from typetraits.
+    when T isnot tuple: result = false
+    else:
+      var t: T
+      for name, _ in t.fieldPairs:
+        when name == "Field0":
+          return compiles(t.Field0)
+        else:
+          return true
+      return false
+
+template tupleObjectDollar*[T: tuple | object](result: var string, x: T) =
+  result = "("
+  const isNamed = T is object or isNamedTuple(typeof(T))
+  var count {.used.} = 0
+  for name, value in fieldPairs(x):
+    if count > 0: result.add(", ")
+    when isNamed:
+      result.add(name)
+      result.add(": ")
+    count.inc
+    when compiles($value):
+      when value isnot string and value isnot seq and compiles(value.isNil):
+        if value.isNil: result.add "nil"
+        else: result.addQuoted(value)
+      else:
+        result.addQuoted(value)
+    else:
+      result.add("...")
+  when not isNamed:
+    if count == 1:
+      result.add(",") # $(1,) should print as the semantically legal (1,)
+  result.add(")")