diff --git a/tests/generics/tbadcache.nim b/tests/generics/tbadcache.nim
new file mode 100644
index 0000000000000..33e65be3ab4db
--- /dev/null
+++ b/tests/generics/tbadcache.nim
@@ -0,0 +1,26 @@
+# issue #16128
+
+import std/[tables, hashes]
+
+type
+  NodeId*[L] = object
+    isSource: bool
+    index: Table[NodeId[L], seq[NodeId[L]]]
+
+func hash*[L](id: NodeId[L]): Hash = discard
+func `==`[L](a, b: NodeId[L]): bool = discard
+
+proc makeIndex*[T, L](tree: T) =
+  var parent = NodeId[L]()
+  var tmp: Table[NodeId[L], seq[NodeId[L]]]
+  tmp[parent] = @[parent]
+
+proc simpleTreeDiff*[T, L](source, target: T) =
+  # Swapping these two lines makes error disappear
+  var m: Table[NodeId[L], NodeId[L]]
+  makeIndex[T, L](target)
+
+var tmp: Table[string, seq[string]] # removing this forward declaration also removes error
+
+proc diff(x1, x2: string): auto =
+  simpleTreeDiff[int, string](12, 12)
diff --git a/tests/generics/tgenericwhen.nim b/tests/generics/tgenericwhen.nim
index e1b23873b4ab9..87672a6995aed 100644
--- a/tests/generics/tgenericwhen.nim
+++ b/tests/generics/tgenericwhen.nim
@@ -44,3 +44,15 @@ block: # constant condition after dynamic one
   doAssert y.a is int
   var z: Foo[float]
   doAssert z.a is string
+
+block: # issue #4774, but not with threads
+  const hasThreadSupport = not defined(js)
+  when hasThreadSupport:
+    type Channel[T] = object
+      value: T
+  type
+    SomeObj[T] = object
+      when hasThreadSupport:
+        channel: ptr Channel[T]
+  var x: SomeObj[int]
+  doAssert compiles(x.channel) == hasThreadSupport
diff --git a/tests/generics/tuninstantiatedgenericcalls.nim b/tests/generics/tuninstantiatedgenericcalls.nim
index 42f5493d7f435..f33fc8967c9bc 100644
--- a/tests/generics/tuninstantiatedgenericcalls.nim
+++ b/tests/generics/tuninstantiatedgenericcalls.nim
@@ -451,3 +451,67 @@ block: # real version of above
   proc foo[T](x: T, a = Opt.none(int)) = discard
   foo(1, a = Opt.none(int))
   foo(1)
+
+block: # issue #20880
+  type
+    Child[n: static int] = object
+      data: array[n, int]
+    Parent[n: static int] = object
+      child: Child[3*n]
+  const n = 3
+  doAssert $(typeof Parent[n*3]()) == "Parent[9]"
+  doAssert $(typeof Parent[1]().child) == "Child[3]"
+  doAssert Parent[1]().child.data.len == 3
+
+{.experimental: "dynamicBindSym".}
+block: # issue #16774
+  type SecretWord = distinct uint64
+  const WordBitWidth = 8 * sizeof(uint64)
+  func wordsRequired(bits: int): int {.compileTime.} =
+    ## Compute the number of limbs required
+    # from the **announced** bit length
+    (bits + WordBitWidth - 1) div WordBitWidth
+  type
+    Curve = enum BLS12_381
+    BigInt[bits: static int] = object
+      limbs: array[bits.wordsRequired, SecretWord]
+  const BLS12_381_Modulus = default(BigInt[381])
+  macro Mod(C: static Curve): untyped =
+    ## Get the Modulus associated to a curve
+    result = bindSym($C & "_Modulus")
+  macro getCurveBitwidth(C: static Curve): untyped =
+    result = nnkDotExpr.newTree(
+      getAST(Mod(C)),
+      ident"bits"
+    )
+  type Fp[C: static Curve] = object
+    ## Finite Fields / Modular arithmetic
+    ## modulo the curve modulus
+    mres: BigInt[getCurveBitwidth(C)]
+  var x: Fp[BLS12_381]
+  doAssert x.mres.limbs.len == wordsRequired(getCurveBitWidth(BLS12_381))
+  # minimized, as if we haven't tested it already:
+  macro makeIntLit(c: static int): untyped =
+    result = newLit(c)
+  type Test[T: static int] = object
+    myArray: array[makeIntLit(T), int]
+  var y: Test[2]
+  doAssert y.myArray.len == 2
+  var z: Test[4]
+  doAssert z.myArray.len == 4
+
+block: # issue #16175
+  type
+    Thing[D: static uint] = object
+      when D == 0:
+        kid: char
+      else:
+        kid: Thing[D-1]
+  var t2 = Thing[3]()
+  doAssert t2.kid is Thing[2.uint]
+  doAssert t2.kid.kid is Thing[1.uint]
+  doAssert t2.kid.kid.kid is Thing[0.uint]
+  doAssert t2.kid.kid.kid.kid is char
+  var s = Thing[1]()
+  doAssert s.kid is Thing[0.uint]
+  doAssert s.kid.kid is char
diff --git a/tests/lent/tvm.nim b/tests/lent/tvm.nim
new file mode 100644
index 0000000000000..5df1d1270bdef
--- /dev/null
+++ b/tests/lent/tvm.nim
@@ -0,0 +1,21 @@
+block: # issue #17527
+  iterator items2[IX, T](a: array[IX, T]): lent T {.inline.} =
+    var i = low(IX)
+    if i <= high(IX):
+      while true:
+        yield a[i]
+        if i >= high(IX): break
+        inc(i)
+
+  proc main() =
+    var s: seq[string] = @[]
+    for i in 0..<3:
+      for (key, val) in items2([("any", "bar")]):
+        s.add $(i, key, val)
+    doAssert s == @[
+      "(0, \"any\", \"bar\")",
+      "(1, \"any\", \"bar\")",
+      "(2, \"any\", \"bar\")"
+    ]
+
+  static: main()
diff --git a/tests/lookups/mdisambsym1.nim b/tests/lookups/mdisambsym1.nim
new file mode 100644
index 0000000000000..b8beca0354adb
--- /dev/null
+++ b/tests/lookups/mdisambsym1.nim
@@ -0,0 +1,2 @@
+proc count*(s: string): int = 
+  s.len
diff --git a/tests/lookups/mdisambsym2.nim b/tests/lookups/mdisambsym2.nim
new file mode 100644
index 0000000000000..1e056311d7487
--- /dev/null
+++ b/tests/lookups/mdisambsym2.nim
@@ -0,0 +1 @@
+var count*: int = 10
diff --git a/tests/lookups/mdisambsym3.nim b/tests/lookups/mdisambsym3.nim
new file mode 100644
index 0000000000000..95bd19702ab25
--- /dev/null
+++ b/tests/lookups/mdisambsym3.nim
@@ -0,0 +1 @@
+const count* = 3.142
diff --git a/tests/lookups/mmacroamb.nim b/tests/lookups/mmacroamb.nim
new file mode 100644
index 0000000000000..107e510550e2a
--- /dev/null
+++ b/tests/lookups/mmacroamb.nim
@@ -0,0 +1,10 @@
+# issue #12732
+
+import std/macros
+const getPrivate3_tmp* = 0
+const foobar1* = 0 # comment this or make private and it'll compile fine
+macro foobar4*(): untyped =
+  newLit "abc"
+template currentPkgDir2*: string = foobar4()
+macro currentPkgDir2*(dir: string): untyped =
+  newLit "abc2"
diff --git a/tests/lookups/tdisambsym.nim b/tests/lookups/tdisambsym.nim
new file mode 100644
index 0000000000000..678528ad669ed
--- /dev/null
+++ b/tests/lookups/tdisambsym.nim
@@ -0,0 +1,8 @@
+# issue #15247
+
+import mdisambsym1, mdisambsym2, mdisambsym3
+
+proc twice(n: int): int =
+  n*2
+
+doAssert twice(count) == 20
diff --git a/tests/lookups/tmacroamb.nim b/tests/lookups/tmacroamb.nim
new file mode 100644
index 0000000000000..854017e7269a6
--- /dev/null
+++ b/tests/lookups/tmacroamb.nim
@@ -0,0 +1,5 @@
+# issue #12732
+
+import mmacroamb
+const s0 = currentPkgDir2 #[tt.Error
+           ^ ambiguous identifier: 'currentPkgDir2' -- use one of the following:]#
diff --git a/tests/overload/tgenericalias.nim b/tests/overload/tgenericalias.nim
new file mode 100644
index 0000000000000..50a44bd32433a
--- /dev/null
+++ b/tests/overload/tgenericalias.nim
@@ -0,0 +1,13 @@
+block: # issue #13799
+  type
+    X[A, B] = object
+      a: A
+      b: B
+
+    Y[A] = X[A, int]
+  template s(T: type X): X = T()
+  template t[A, B](T: type X[A, B]): X[A, B] = T()
+  proc works1(): Y[int] = s(X[int, int])
+  proc works2(): Y[int] = t(X[int, int])
+  proc works3(): Y[int] = t(Y[int])
+  proc broken(): Y[int] = s(Y[int])
diff --git a/tests/overload/tor_isnt_better.nim b/tests/overload/tor_isnt_better.nim
index be1ad67bf68e3..bee125386a96b 100644
--- a/tests/overload/tor_isnt_better.nim
+++ b/tests/overload/tor_isnt_better.nim
@@ -16,3 +16,26 @@ block: # bug #8568
   proc g(a: D|E): string = "foo D|E"
   proc g(a: D): string = "foo D"
   doAssert g(D[int]()) == "foo D"
+
+type Obj1[T] = object
+  v: T
+converter toObj1[T](t: T): Obj1[T] = return Obj1[T](v: t)
+block: # issue #10019
+  proc fun1[T](elements: seq[T]): string = "fun1 seq"
+  proc fun1(o: object|tuple): string = "fun1 object|tuple"
+  proc fun2[T](elements: openArray[T]): string = "fun2 openarray"
+  proc fun2(o: object): string = "fun2 object"
+  proc fun_bug[T](elements: openArray[T]): string = "fun_bug openarray"
+  proc fun_bug(o: object|tuple):string = "fun_bug object|tuple"
+  proc main() =
+    var x = @["hello", "world"]
+    block:
+      # no ambiguity error shown here even though this would compile if we remove either 1st or 2nd overload of fun1
+      doAssert fun1(x) == "fun1 seq"
+    block:
+      # ditto
+      doAssert fun2(x) == "fun2 openarray"
+    block:
+      # Error: ambiguous call; both t0065.fun_bug(elements: openarray[T])[declared in t0065.nim(17, 5)] and t0065.fun_bug(o: object or tuple)[declared in t0065.nim(20, 5)] match for: (array[0..1, string])
+      doAssert fun_bug(x) == "fun_bug openarray"
+  main()
diff --git a/tests/overload/tuntypedarg.nim b/tests/overload/tuntypedarg.nim
new file mode 100644
index 0000000000000..9aa4fad3b9c7a
--- /dev/null
+++ b/tests/overload/tuntypedarg.nim
@@ -0,0 +1,19 @@
+import macros
+
+block: # issue #7385
+  type CustomSeq[T] = object
+    data: seq[T]
+  macro `[]`[T](s: CustomSeq[T], args: varargs[untyped]): untyped =
+    ## The end goal is to replace the joker "_" by something else
+    result = newIntLitNode(10)
+  proc foo1(): CustomSeq[int] =
+    result.data.newSeq(10)
+    # works since no overload matches first argument with type `CustomSeq`
+    # except magic `[]`, which always matches without checking arguments
+    doAssert result[_] == 10
+  doAssert foo1() == CustomSeq[int](data: newSeq[int](10))
+  proc foo2[T](): CustomSeq[T] =
+    result.data.newSeq(10)
+    # works fine with generic return type
+    doAssert result[_] == 10
+  doAssert foo2[int]() == CustomSeq[int](data: newSeq[int](10))
diff --git a/tests/proc/texplicitgenerics.nim b/tests/proc/texplicitgenerics.nim
index 8a90f42662aef..833d77b3b790e 100644
--- a/tests/proc/texplicitgenerics.nim
+++ b/tests/proc/texplicitgenerics.nim
@@ -43,3 +43,13 @@ block: # ditto but may be wrong minimization
   # alternative version, also causes instantiation issue
   proc baz[T](x: typeof(foo[T]())) = discard
   baz[int](Foo[int]())
+
+block: # issue #21346
+  type K[T] = object
+  template s[T](x: int) = doAssert T is K[K[int]]
+  proc b1(n: bool | bool) = s[K[K[int]]](3)
+  proc b2(n: bool)        = s[K[K[int]]](3)
+  template b3(n: bool)    = s[K[K[int]]](3)
+  b1(false)     # Error: cannot instantiate K; got: <T> but expected: <T>
+  b2(false)     # Builds, on its own
+  b3(false)
diff --git a/tests/proc/tgenericdefaultparam.nim b/tests/proc/tgenericdefaultparam.nim
index 7f553ab37fd1b..2d0f850c25a03 100644
--- a/tests/proc/tgenericdefaultparam.nim
+++ b/tests/proc/tgenericdefaultparam.nim
@@ -67,3 +67,14 @@ block: # issue #24099, modified to work but using float32
     ## Compares colors with given accuracy.
     abs(a[0] - b[0]) < e and abs(a[1] - b[1]) < e and abs(a[2] - b[2]) < e
   doAssert ColorRGBU([1.float32, 1, 1]) ~= ColorRGBU([1.float32, 1, 1])
+
+block: # issue #13270
+  type
+    A = object
+    B = object
+  proc f(a: A) = discard
+  proc g[T](value: T, cb: (proc(a: T)) = f) =
+    cb value
+  g A()
+  # This should fail because there is no f(a: B) overload available
+  doAssert not compiles(g B())
diff --git a/tests/stdlib/tmarshalsegfault.nim b/tests/stdlib/tmarshalsegfault.nim
new file mode 100644
index 0000000000000..a18ace6d116d3
--- /dev/null
+++ b/tests/stdlib/tmarshalsegfault.nim
@@ -0,0 +1,55 @@
+# issue #12405
+
+import std/[marshal, streams, times, tables, os, assertions]
+
+type AiredEpisodeState * = ref object
+    airedAt * : DateTime
+    tvShowId * : string
+    seasonNumber * : int
+    number * : int
+    title * : string
+
+type ShowsWatchlistState * = ref object
+    aired * : seq[AiredEpisodeState]
+
+type UiState * = ref object
+    shows: ShowsWatchlistState
+
+# Helpers to marshal and unmarshal
+proc load * ( state : var UiState, file : string ) =
+    var strm = newFileStream( file, fmRead )
+
+    strm.load( state )
+
+    strm.close()
+
+proc store * ( state : UiState, file : string ) =
+    var strm = newFileStream( file, fmWrite )
+
+    strm.store( state )
+
+    strm.close()
+
+# 1. We fill the state initially
+var state : UiState = UiState( shows: ShowsWatchlistState( aired: @[] ) )
+
+# VERY IMPORTANT: For some reason, small numbers (like 2 or 3) don't trigger the bug. Anything above 7 or 8 on my machine triggers though
+for i in 0..30:
+    var episode = AiredEpisodeState( airedAt: now(), tvShowId: "1", seasonNumber: 1, number: 1, title: "string" )
+
+    state.shows.aired.add( episode )
+
+# 2. Store it in a file with the marshal module, and then load it back up
+store( state, "tmarshalsegfault_data" )
+load( state, "tmarshalsegfault_data" )
+removeFile("tmarshalsegfault_data")
+
+# 3. VERY IMPORTANT: Without this line, for some reason, everything works fine
+state.shows.aired[ 0 ] = AiredEpisodeState( airedAt: now(), tvShowId: "1", seasonNumber: 1, number: 1, title: "string" )
+
+# 4. And formatting the airedAt date will now trigger the exception
+var s = ""
+for ep in state.shows.aired:
+    let x = $ep.seasonNumber & "x" & $ep.number & " (" & $ep.airedAt & ")"
+    if s.len == 0: s = x
+    else: doAssert s == x