From 1b41c3122be1fa2628d814893a4f3a1196b762fc Mon Sep 17 00:00:00 2001
From: Timothee Cour <timothee.cour2@gmail.com>
Date: Mon, 29 Jun 2020 00:34:05 -0700
Subject: [PATCH] fix #13432 typetraits.$: $(int,) is now (int,); $tuple[] is
 now tuple[] (#14799)

* typetraits.$: $(int,) is now (int,); $tuple[] is now tuple[]

* changelog
---
 changelog.md                   |  1 +
 compiler/types.nim             |  3 ++-
 lib/pure/typetraits.nim        | 21 ---------------------
 tests/metatype/ttypetraits.nim | 31 +++++++++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 22 deletions(-)

diff --git a/changelog.md b/changelog.md
index 54996ea34..d5f3c8aa9 100644
--- a/changelog.md
+++ b/changelog.md
@@ -115,6 +115,7 @@
 - `macros.newLit` now preserves named vs unnamed tuples; use `-d:nimHasWorkaround14720` to keep old behavior
 - Add `random.gauss`, that uses the ratio of uniforms method of sampling from a Gaussian distribution.
 - Add `typetraits.elementType` to get element type of an iterable.
+- `typetraits.$`: `$(int,)` is now `"(int,)"`; `$tuple[]` is now `"tuple[]"`
 
 ## Language changes
 - In the newruntime it is now allowed to assign to the discriminator field
diff --git a/compiler/types.nim b/compiler/types.nim
index b8f58c950..0be0b3eed 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -634,13 +634,14 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
           if i < t.n.len - 1: result.add(", ")
         result.add(']')
       elif t.len == 0:
-        result = "tuple"
+        result = "tuple[]"
       else:
         if prefer == preferTypeName: result = "("
         else: result = "tuple of ("
         for i in 0..<t.len:
           result.add(typeToString(t[i]))
           if i < t.len - 1: result.add(", ")
+          elif t.len == 1: result.add(",")
         result.add(')')
     of tyPtr, tyRef, tyVar, tyLent:
       result = typeToStr[t.kind]
diff --git a/lib/pure/typetraits.nim b/lib/pure/typetraits.nim
index 346ac06d4..c289f6c84 100644
--- a/lib/pure/typetraits.nim
+++ b/lib/pure/typetraits.nim
@@ -149,24 +149,3 @@ since (1, 1):
 
     type T2 = T
     genericParamsImpl(T2)
-
-when isMainModule:
-  static:
-    doAssert $type(42) == "int"
-    doAssert int.name == "int"
-
-  const a1 = name(int)
-  const a2 = $(int)
-  const a3 = $int
-  doAssert a1 == "int"
-  doAssert a2 == "int"
-  doAssert a3 == "int"
-
-  proc fun[T: typedesc](t: T) =
-    const a1 = name(t)
-    const a2 = $(t)
-    const a3 = $t
-    doAssert a1 == "int"
-    doAssert a2 == "int"
-    doAssert a3 == "int"
-  fun(int)
diff --git a/tests/metatype/ttypetraits.nim b/tests/metatype/ttypetraits.nim
index d0480415e..b69ca4c60 100644
--- a/tests/metatype/ttypetraits.nim
+++ b/tests/metatype/ttypetraits.nim
@@ -26,6 +26,37 @@ proc typeToString*(t: typedesc, prefer = "preferTypeName"): string {.magic: "Typ
   ## prefer = "preferResolved" will resolve type aliases recursively.
   # Move to typetraits.nim once api stabilized.
 
+block: # name, `$`
+  static:
+    doAssert $type(42) == "int"
+    doAssert int.name == "int"
+
+  const a1 = name(int)
+  const a2 = $(int)
+  const a3 = $int
+  doAssert a1 == "int"
+  doAssert a2 == "int"
+  doAssert a3 == "int"
+
+  proc fun[T: typedesc](t: T) =
+    const a1 = name(t)
+    const a2 = $(t)
+    const a3 = $t
+    doAssert a1 == "int"
+    doAssert a2 == "int"
+    doAssert a3 == "int"
+  fun(int)
+
+  doAssert $(int,) == "(int,)"
+  doAssert $(1,) == "(1,)" # just for comparison to make sure it has same structure
+  doAssert $tuple[] == "tuple[]"
+  doAssert $(int,) == "(int,)"
+  doAssert $(int, float) == "(int, float)"
+  doAssert $((int), tuple[], tuple[a: uint], tuple[a: uint, b: float], (int,), (int, float)) == "(int, tuple[], tuple[a: uint], tuple[a: uint, b: float], tuple of (int,), tuple of (int, float))"
+  # xxx this is inconsistent, it should be:
+  # "(int, tuple[], tuple[a: uint], tuple[a: uint, b: float], (int,), (int, float))"
+  # which matches how you write it, is consistent with `$(int,)`, and is un-ambiguous.
+
 block: # typeToString
   type MyInt = int
   type