Merge remote-tracking branch 'upstream/devel' into test-6434

2 files changed, 12 insertions, 8 deletions

diff --git a/lib/pure/typetraits.nim b/lib/pure/typetraits.nim
index e9579e824..c53b68864 100644
--- a/lib/pure/typetraits.nim
+++ b/lib/pure/typetraits.nim
@@ -35,8 +35,13 @@ proc `$`*(t: typedesc): string =
   ## An alias for `name`.
   name(t)
 
-proc arity*(t: typedesc): int {.magic: "TypeTrait".}
-  ## Returns the arity of the given type
+proc arity*(t: typedesc): int {.magic: "TypeTrait".} =
+  ## Returns the arity of the given type. This is the number of "type" components or
+  ## the number of generic parameters a given type ``t`` has.
+  runnableExamples:
+    assert arity(seq[string]) == 1
+    assert arity(array[3, int]) == 2
+    assert arity((int, int, float, string)) == 4
 
 proc genericHead*(t: typedesc): typedesc {.magic: "TypeTrait".}
   ## Accepts an instantiated generic type and returns its
@@ -47,11 +52,11 @@ proc genericHead*(t: typedesc): typedesc {.magic: "TypeTrait".}
   ##   seq[int].genericHead[float] will be seq[float]
   ##
   ## A compile-time error will be produced if the supplied type
-  ## is not generic
+  ## is not generic.
 
 proc stripGenericParams*(t: typedesc): typedesc {.magic: "TypeTrait".}
   ## This trait is similar to `genericHead`, but instead of producing
-  ## error for non-generic types, it will just return them unmodified
+  ## error for non-generic types, it will just return them unmodified.
 
 proc supportsCopyMem*(t: typedesc): bool {.magic: "TypeTrait".}
   ## This trait returns true iff the type ``t`` is safe to use for
diff --git a/lib/system/sysio.nim b/lib/system/sysio.nim
index df13ab628..61835e0f7 100644
--- a/lib/system/sysio.nim
+++ b/lib/system/sysio.nim
@@ -145,10 +145,9 @@ proc readLine(f: File, line: var TaintedString): bool =
   var pos = 0
 
   # Use the currently reserved space for a first try
-  var sp = line.string.len
-  if sp == 0:
-    sp = 80
-    line.string.setLen(sp)
+  var sp = max(line.string.len, 80)
+  line.string.setLen(sp)
+
   while true:
     # memset to \L so that we can tell how far fgets wrote, even on EOF, where
     # fgets doesn't append an \L