typeToString can now show (recursively) resolved type aliases; fixes #8569 #8083 #8570 (#11678)

* nested typeToString
* typeToString: preferResolved
* add test
* fix test
* preferMixed
* fix tests

compiler/semmagic.nim

@@ -141,6 +141,14 @@ proc evalTypeTrait(c: PContext; traitCall: PNode, operand: PType, context: PSym)
     return typeWithSonsResult(tyAnd, @[operand, operand2])
   of "not":
     return typeWithSonsResult(tyNot, @[operand])
+  of "typeToString":
+    var prefer = preferTypeName
+    if traitCall.sons.len >= 2:
+      let preferStr = traitCall.sons[2].strVal
+      prefer = parseEnum[TPreferedDesc](preferStr)
+    result = newStrNode(nkStrLit, operand.typeToString(prefer))
+    result.typ = newType(tyString, context)
+    result.info = traitCall.info
   of "name", "$":
     result = newStrNode(nkStrLit, operand.typeToString(preferTypeName))
     result.typ = newType(tyString, context)

compiler/types.nim

@@ -15,8 +15,14 @@ import
 
 type
   TPreferedDesc* = enum
-    preferName, preferDesc, preferExported, preferModuleInfo, preferGenericArg,
+    preferName, # default
-    preferTypeName
+    preferDesc, # probably should become what preferResolved is
+    preferExported,
+    preferModuleInfo, # fully qualified
+    preferGenericArg,
+    preferTypeName,
+    preferResolved, # fully resolved symbols
+    preferMixed, # show symbol + resolved symbols if it differs, eg: seq[cint{int32}, float]
 
 proc typeToString*(typ: PType; prefer: TPreferedDesc = preferName): string
 template `$`*(typ: PType): string = typeToString(typ)
@@ -121,6 +127,7 @@ proc isFloatLit*(t: PType): bool {.inline.} =
 
 proc getProcHeader*(conf: ConfigRef; sym: PSym; prefer: TPreferedDesc = preferName; getDeclarationPath = true): string =
   assert sym != nil
+  # consider using `skipGenericOwner` to avoid fun2.fun2 when fun2 is generic
   result = sym.owner.name.s & '.' & sym.name.s
   if sym.kind in routineKinds:
     result.add '('
@@ -415,12 +422,12 @@ proc rangeToStr(n: PNode): string =
   result = valueToString(n.sons[0]) & ".." & valueToString(n.sons[1])
 
 const
-  typeToStr: array[TTypeKind, string] = ["None", "bool", "Char", "empty",
+  typeToStr: array[TTypeKind, string] = ["None", "bool", "char", "empty",
     "Alias", "nil", "untyped", "typed", "typeDesc",
     "GenericInvocation", "GenericBody", "GenericInst", "GenericParam",
     "distinct $1", "enum", "ordinal[$1]", "array[$1, $2]", "object", "tuple",
     "set[$1]", "range[$1]", "ptr ", "ref ", "var ", "seq[$1]", "proc",
-    "pointer", "OpenArray[$1]", "string", "CString", "Forward",
+    "pointer", "OpenArray[$1]", "string", "cstring", "Forward",
     "int", "int8", "int16", "int32", "int64",
     "float", "float32", "float64", "float128",
     "uint", "uint8", "uint16", "uint32", "uint64",
@@ -431,7 +438,8 @@ const
     "and", "or", "not", "any", "static", "TypeFromExpr", "FieldAccessor",
     "void"]
 
-const preferToResolveSymbols = {preferName, preferTypeName, preferModuleInfo, preferGenericArg}
+const preferToResolveSymbols = {preferName, preferTypeName, preferModuleInfo,
+  preferGenericArg, preferResolved, preferMixed}
 
 template bindConcreteTypeToUserTypeClass*(tc, concrete: PType) =
   tc.sons.add concrete
@@ -450,7 +458,16 @@ proc addTypeFlags(name: var string, typ: PType) {.inline.} =
   if tfNotNil in typ.flags: name.add(" not nil")
 
 proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
-  var t = typ
+  let preferToplevel = prefer
+  proc getPrefer(prefer: TPreferedDesc): TPreferedDesc =
+    if preferToplevel in {preferResolved, preferMixed}:
+      preferToplevel # sticky option
+    else:
+      prefer
+
+  proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
+    let prefer = getPrefer(prefer)
+    let t = typ
     result = ""
     if t == nil: return
     if prefer in preferToResolveSymbols and t.sym != nil and
@@ -459,7 +476,21 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
         result = t.sym.name.s & " literal(" & $t.n.intVal & ")"
       elif t.kind == tyAlias and t.sons[0].kind != tyAlias:
         result = typeToString(t.sons[0])
+      elif prefer in {preferResolved, preferMixed}:
+        case t.kind
+        of IntegralTypes + {tyFloat..tyFloat128} + {tyString, tyCString}:
+          result = typeToStr[t.kind]
+        of tyGenericBody:
+          result = typeToString(t.lastSon)
+        of tyCompositeTypeClass:
+          # avoids showing `A[any]` in `proc fun(a: A)` with `A = object[T]`
+          result = typeToString(t.lastSon.lastSon)
+        else:
+          result = t.sym.name.s
+        if prefer == preferMixed and result != t.sym.name.s:
+          result = t.sym.name.s & "{" & result & "}"
       elif prefer in {preferName, preferTypeName} or t.sym.owner.isNil:
+        # note: should probably be: {preferName, preferTypeName, preferGenericArg}
         result = t.sym.name.s
         if t.kind == tyGenericParam and t.sonsLen > 0:
           result.add ": "
@@ -521,7 +552,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
         of tyProc: "proc"
         of tyObject: "object"
         of tyTuple: "tuple"
-      of tyOpenArray: "openarray"
+        of tyOpenArray: "openArray"
         else: typeToStr[t.base.kind]
     of tyInferred:
       let concrete = t.previouslyInferred
@@ -572,7 +603,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
     of tySet:
       result = "set[" & typeToString(t.sons[0]) & ']'
     of tyOpenArray:
-    result = "openarray[" & typeToString(t.sons[0]) & ']'
+      result = "openArray[" & typeToString(t.sons[0]) & ']'
     of tyDistinct:
       result = "distinct " & typeToString(t.sons[0],
         if prefer == preferModuleInfo: preferModuleInfo else: preferTypeName)
@@ -652,6 +683,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
     else:
       result = typeToStr[t.kind]
     result.addTypeFlags(t)
+  result = typeToString(typ, prefer)
 
 proc firstOrd*(conf: ConfigRef; t: PType): Int128 =
   case t.kind

tests/errmsgs/tsigmatch.nim

@@ -36,7 +36,7 @@ tsigmatch.nim(143, 13) Error: type mismatch: got <array[0..0, proc (x: int){.gcs
 but expected one of:
 proc takesFuncs(fs: openArray[proc (x: int) {.gcsafe, locks: 0.}])
   first type mismatch at position: 1
-  required type for fs: openarray[proc (x: int){.closure, gcsafe, locks: 0.}]
+  required type for fs: openArray[proc (x: int){.closure, gcsafe, locks: 0.}]
   but expression '[proc (x: int) {.gcsafe, locks: 0.} = echo [x]]' is of type: array[0..0, proc (x: int){.gcsafe, locks: 0.}]
 
 expression: takesFuncs([proc (x: int) {.gcsafe, locks: 0.} = echo [x]])

tests/errmsgs/twrong_at_operator.nim

@@ -6,7 +6,7 @@ twrong_at_operator.nim(22, 30) Error: type mismatch: got <array[0..0, type int]>
 but expected one of:
 proc `@`[T](a: openArray[T]): seq[T]
   first type mismatch at position: 1
-  required type for a: openarray[T]
+  required type for a: openArray[T]
   but expression '[int]' is of type: array[0..0, type int]
 proc `@`[IDX, T](a: sink array[IDX, T]): seq[T]
   first type mismatch at position: 1

tests/metatype/ttypetraits2.nim

@@ -14,3 +14,32 @@ block: # isNamedTuple
   doAssert not Foo3.isNamedTuple
   doAssert not Foo4.isNamedTuple
   doAssert not (1,).type.isNamedTuple
+
+proc typeToString*(t: typedesc, prefer = "preferTypeName"): string {.magic: "TypeTrait".}
+  ## Returns the name of the given type, with more flexibility than `name`,
+  ## and avoiding the potential clash with a variable named `name`.
+  ## prefer = "preferResolved" will resolve type aliases recursively.
+  # Move to typetraits.nim once api stabilized.
+
+block: # typeToString
+  type MyInt = int
+  type
+    C[T0, T1] = object
+  type C2=C # alias => will resolve as C
+  type C2b=C # alias => will resolve as C (recursively)
+  type C3[U,V] = C[V,U]
+  type C4[X] = C[X,X]
+  template name2(T): string = typeToString(T, "preferResolved")
+  doAssert MyInt.name2 == "int"
+  doAssert C3[MyInt, C2b].name2 == "C3[int, C]"
+    # C3 doesn't get resolved to C, not an alias (nor does C4)
+  doAssert C2b[MyInt, C4[cstring]].name2 == "C[int, C4[cstring]]"
+  doAssert C4[MyInt].name2 == "C4[int]"
+  when BiggestFloat is float and cint is int:
+    doAssert C2b[cint, BiggestFloat].name2 == "C3[int, C3[float, int32]]"
+
+  template name3(T): string = typeToString(T, "preferMixed")
+  doAssert MyInt.name3 == "MyInt{int}"
+  doAssert (tuple[a: MyInt, b: float]).name3 == "tuple[a: MyInt{int}, b: float]"
+  doAssert (tuple[a: C2b[MyInt, C4[cstring]], b: cint, c: float]).name3 ==
+    "tuple[a: C2b{C}[MyInt{int}, C4[cstring]], b: cint{int32}, c: float]"

tests/openarray/t8259.nim

@@ -1,5 +1,5 @@
 discard """
-  errormsg: "invalid type: 'openarray[int]' for result"
+  errormsg: "invalid type: 'openArray[int]' for result"
   line: 6
 """