proper error message for out-of-range enum sets (#24027)

fixes #17848

3 files changed, 74 insertions, 3 deletions

diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 0c3691362..91e318a63 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -648,7 +648,14 @@ proc overloadedCallOpr(c: PContext, n: PNode): PNode =
 
 proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
   case n.kind
-  of nkCurly, nkBracket:
+  of nkCurly:
+    for i in 0..<n.len:
+      if n[i].kind == nkRange:
+        changeType(c, n[i][0], elemType(newType), check)
+        changeType(c, n[i][1], elemType(newType), check)
+      else:
+        changeType(c, n[i], elemType(newType), check)
+  of nkBracket:
     for i in 0..<n.len:
       changeType(c, n[i], elemType(newType), check)
   of nkPar, nkTupleConstr:
@@ -685,10 +692,16 @@ proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
       let value = n.intVal
       if value < firstOrd(c.config, newType) or value > lastOrd(c.config, newType):
         localError(c.config, n.info, "cannot convert " & $value &
-                                         " to " & typeToString(newType))
+                                         " to " & typeNameAndDesc(newType))
   of nkFloatLit..nkFloat64Lit:
     if check and not floatRangeCheck(n.floatVal, newType):
-      localError(c.config, n.info, errFloatToString % [$n.floatVal, typeToString(newType)])
+      localError(c.config, n.info, errFloatToString % [$n.floatVal, typeNameAndDesc(newType)])
+  of nkSym:
+    if check and n.sym.kind == skEnumField and not sameTypeOrNil(n.sym.typ, newType):
+      let value = n.sym.position
+      if value < firstOrd(c.config, newType) or value > lastOrd(c.config, newType):
+        localError(c.config, n.info, "cannot convert '" & n.sym.name.s &
+                                         "' to '" & typeNameAndDesc(newType) & "'")
   else: discard
   n.typ = newType
 
diff --git a/compiler/types.nim b/compiler/types.nim
index 93da2cc9b..1c434fbfa 100644
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -1739,6 +1739,13 @@ proc processPragmaAndCallConvMismatch(msg: var string, formal, actual: PType, co
     of efTagsIllegal:
       msg.add "\n.notTag catched an illegal effect"
 
+proc typeNameAndDesc*(t: PType): string =
+  result = typeToString(t)
+  let desc = typeToString(t, preferDesc)
+  if result != desc:
+    result.add(" = ")
+    result.add(desc)
+
 proc typeMismatch*(conf: ConfigRef; info: TLineInfo, formal, actual: PType, n: PNode) =
   if formal.kind != tyError and actual.kind != tyError:
     let actualStr = typeToString(actual)
diff --git a/tests/sets/twrongenumrange.nim b/tests/sets/twrongenumrange.nim
new file mode 100644
index 000000000..fc90c142f
--- /dev/null
+++ b/tests/sets/twrongenumrange.nim
@@ -0,0 +1,51 @@
+discard """
+  cmd: "nim check --hints:off $file"
+"""
+
+# issue #17848
+
+block:
+  # generate with:
+  # var a = ""
+  # for i in 0..<80: a.add "k" & $i & ", "
+  # echo a
+  type
+    TMsgKind = enum
+      k0, k1, k2, k3, k4, k5, k6, k7, k8, k9, k10, k11, k12, k13, k14, k15, k16, k17, k18, k19, k20, k21, k22, k23, k24, k25, k26, k27, k28, k29, k30, k31, k32, k33, k34, k35, k36, k37, k38, k39, k40, k41, k42, k43, k44, k45, k46, k47, k48, k49, k50, k51, k52, k53, k54, k55, k56, k57, k58, k59, k60, k61, k62, k63, k64, k65, k66, k67, k68, k69, k70, k71, k72, k73, k74, k75, k76, k77, k78, k79
+  type
+    TNoteKind = range[k10..k79]
+    Conf = ref object
+      notes: set[TNoteKind]
+  proc bad(conf: Conf, noteSet: set[TMsgKind]) =
+    conf.notes = noteSet #[tt.Error
+                 ^ type mismatch: got <set[TMsgKind]> but expected 'set[TNoteKind]']#
+  var conf = Conf()
+  bad(conf, {k10..k60})
+
+block:
+  type
+    TMsgKind = enum k0, k1, k2, k3
+    TNoteKind = range[k1..k2]
+    TNoteKinds = set[TNoteKind]
+  type Conf = ref object
+    notes: TNoteKinds
+  proc fn(conf: Conf, b: set[TMsgKind]) =
+    conf.notes = b #[tt.Error
+                 ^ type mismatch: got <set[TMsgKind]> but expected 'TNoteKinds = set[TNoteKind]']#
+  var conf = Conf()
+  conf.fn({k0..k3}) # BUG: this should give error
+  echo conf.notes # {k1, k2}
+
+block:
+  #[
+  compiler/bitsets.nim(43, 9) `elem >= 0`  [AssertionDefect]
+  ]#
+  type
+    TMsgKind = enum k0, k1, k2, k3
+    TNoteKind = range[k1..k2]
+  var notes: set[TNoteKind]
+  notes = {k0} #[tt.Error
+           ^ cannot convert 'k0' to 'TNoteKind = range 1..2(TMsgKind)]#
+  notes = {k0..k3} #[tt.Error
+           ^ cannot convert 'k0' to 'TNoteKind = range 1..2(TMsgKind)'; tt.Error
+               ^ cannot convert 'k3' to 'TNoteKind = range 1..2(TMsgKind)']#