fixes #7247

changelog.md

@@ -241,9 +241,6 @@ styledEcho "Red on Green.", resetStyle
   and it no longer raises an OS error but returns an ``osInvalidSocket`` when
   creation fails.
 - ``newNativeSocket`` is now named ``createNativeSocket``.
-- Type inference for generic type parameters involving numeric types is now symetric. See
-  [Generic type inference for numeric types](https://nim-lang.org/docs/manual.html#generics-generic-type-inference-fornumeric-types)
-  for more information.
 - The ``deprecated`` pragma now supports a user-definable warning message for procs.
 
 ```nim

compiler/sigmatch.nim

@@ -915,24 +915,25 @@ proc isCovariantPtr(c: var TCandidate, f, a: PType): bool =
   else:
     return false
 
-proc maxNumericType(prev, candidate: PType): PType =
-  let c = candidate.skipTypes({tyRange})
-  template greater(s) =
-    if c.kind in s: result = c
-  case prev.kind
-  of tyInt: greater({tyInt64})
-  of tyInt8: greater({tyInt, tyInt16, tyInt32, tyInt64})
-  of tyInt16: greater({tyInt, tyInt32, tyInt64})
-  of tyInt32: greater({tyInt64})
+when false:
+  proc maxNumericType(prev, candidate: PType): PType =
+    let c = candidate.skipTypes({tyRange})
+    template greater(s) =
+      if c.kind in s: result = c
+    case prev.kind
+    of tyInt: greater({tyInt64})
+    of tyInt8: greater({tyInt, tyInt16, tyInt32, tyInt64})
+    of tyInt16: greater({tyInt, tyInt32, tyInt64})
+    of tyInt32: greater({tyInt64})
 
-  of tyUInt: greater({tyUInt64})
-  of tyUInt8: greater({tyUInt, tyUInt16, tyUInt32, tyUInt64})
-  of tyUInt16: greater({tyUInt, tyUInt32, tyUInt64})
-  of tyUInt32: greater({tyUInt64})
+    of tyUInt: greater({tyUInt64})
+    of tyUInt8: greater({tyUInt, tyUInt16, tyUInt32, tyUInt64})
+    of tyUInt16: greater({tyUInt, tyUInt32, tyUInt64})
+    of tyUInt32: greater({tyUInt64})
 
-  of tyFloat32: greater({tyFloat64, tyFloat128})
-  of tyFloat64: greater({tyFloat128})
-  else: discard
+    of tyFloat32: greater({tyFloat64, tyFloat128})
+    of tyFloat64: greater({tyFloat128})
+    else: discard
 
 proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
                  flags: TTypeRelFlags = {}): TTypeRelation =
@@ -1145,12 +1146,12 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
           fRange = prev
       let ff = f.sons[1].skipTypes({tyTypeDesc})
       let aa = a.sons[1].skipTypes({tyTypeDesc})
-      
+
       if f.sons[0].kind != tyGenericParam and aa.kind == tyEmpty:
-        result = isGeneric  
+        result = isGeneric
       else:
         result = typeRel(c, ff, aa)
-     
+
       if result < isGeneric:
         if nimEnableCovariance and
            trNoCovariance notin flags and
@@ -1631,13 +1632,15 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
       # Special type binding rule for numeric types.
       # See section "Generic type inference for numeric types" of the
       # manual for further details:
-      let rebinding = maxNumericType(x.skipTypes({tyRange}), a)
-      if rebinding != nil:
-        put(c, f, rebinding)
-        result = isGeneric
-      else:
-        result = typeRel(c, x, a) # check if it fits
-        if result > isGeneric: result = isGeneric
+      when false:
+        let rebinding = maxNumericType(x.skipTypes({tyRange}), a)
+        if rebinding != nil:
+          put(c, f, rebinding)
+          result = isGeneric
+        else:
+          discard
+      result = typeRel(c, x, a) # check if it fits
+      if result > isGeneric: result = isGeneric
   of tyStatic:
     let prev = PType(idTableGet(c.bindings, f))
     if prev == nil:

doc/manual/generics.txt

@@ -713,29 +713,3 @@ definition):
 But a ``bind`` is rarely useful because symbol binding from the definition
 scope is the default.
 
-
-Generic type inference for numeric types
-----------------------------------------
-
-A `numeric`:idx: type is any signed, unsigned integer type, floating point
-type or a subrange thereof. Let ``maxNumericType(T1, T2)`` be the "greater"
-type of ``T1`` and ``T2``, that is the type that uses more bits. For
-example ``maxNumericType(int32, int64) == int64``. ``maxNumericType`` is only
-defined for numeric types of the same class (signed, unsigned, floating point).
-``maxNumericType`` strips away subranges,
-``maxNumericType(subrangeof(int16), int8)`` produces ``int16`` not its
-subrange. The definition ``maxNumericType`` is extended to take a variable
-number of arguments in the obvious way;
-``maxNumericType(x, y, z) == maxNumericType(maxNumericType(x, y), z)``.
-
-A generic type parameter ``T`` that is bound to multiple numeric types ``N1``,
-``N2``, ``N3``, ... during type checking is inferred to
-be ``maxNumericType(N1, N2, N3, ...)``. This special type inference rule ensures
-that the builtin arithmetic operators can be written in an intuitive way:
-
-.. code-block:: nim
-  proc `@`[T: int|int16|int32](x, y: T): T
-
-  4'i32 @ 6'i64 # inferred to be of type ``int64``
-
-  4'i64 @ 6'i32 # inferred to be of type ``int64``

tests/generics/tspecial_numeric_inference.nim

@@ -1,12 +1,21 @@
 discard """
-  output: '''int64
-int64'''
+  output: '''false'''
 """
 
-import typetraits
+when false:
+  import typetraits
 
-proc `@`[T: SomeInteger](x, y: T): T = x
+  proc `@`[T: SomeInteger](x, y: T): T = x
 
-echo(type(5'i64 @ 6'i32))
+  echo(type(5'i64 @ 6'i32))
 
-echo(type(5'i32 @ 6'i64))
+  echo(type(5'i32 @ 6'i64))
+
+import sets
+# bug #7247
+type
+  n8 = range[0'i8..127'i8]
+
+var tab = initSet[n8]()
+
+echo tab.contains(8)