the compiler uses tyAlias internally; tester compiles again

compiler/ccgtypes.nim

@@ -106,6 +106,7 @@ proc typeName(typ: PType): Rope =
            else: ~"TY"
 
 proc getTypeName(m: BModule; typ: PType; sig: SigHash): Rope =
+  let typ = if typ.kind == tyAlias: typ.lastSon else: typ
   if typ.sym != nil and {sfImportc, sfExportc} * typ.sym.flags != {}:
     result = typ.sym.loc.r
   else:

compiler/cgen.nim

@@ -190,21 +190,24 @@ proc freshLineInfo(p: BProc; info: TLineInfo): bool =
     result = true
 
 proc genLineDir(p: BProc, t: PNode) =
-  var line = t.info.safeLineNm
+  let info = t.info
+  #if t.kind in nkCallKinds+{nkStmtListExpr} and t.len > 1: t[1].info
+  #else: t.info
+  var line = info.safeLineNm
   if optEmbedOrigSrc in gGlobalOptions:
-    add(p.s(cpsStmts), ~"//" & t.info.sourceLine & rnl)
-  genCLineDir(p.s(cpsStmts), t.info.toFullPath, line)
+    add(p.s(cpsStmts), ~"//" & info.sourceLine & rnl)
+  genCLineDir(p.s(cpsStmts), info.toFullPath, line)
   if ({optStackTrace, optEndb} * p.options == {optStackTrace, optEndb}) and
       (p.prc == nil or sfPure notin p.prc.flags):
-    if freshLineInfo(p, t.info):
+    if freshLineInfo(p, info):
       linefmt(p, cpsStmts, "#endb($1, $2);$n",
-              line.rope, makeCString(toFilename(t.info)))
+              line.rope, makeCString(toFilename(info)))
   elif ({optLineTrace, optStackTrace} * p.options ==
       {optLineTrace, optStackTrace}) and
-      (p.prc == nil or sfPure notin p.prc.flags) and t.info.fileIndex >= 0:
-    if freshLineInfo(p, t.info):
+      (p.prc == nil or sfPure notin p.prc.flags) and info.fileIndex >= 0:
+    if freshLineInfo(p, info):
       linefmt(p, cpsStmts, "nimln($1, $2);$n",
-              line.rope, t.info.quotedFilename)
+              line.rope, info.quotedFilename)
 
 proc postStmtActions(p: BProc) {.inline.} =
   add(p.s(cpsStmts), p.module.injectStmt)

compiler/semstmts.nim

@@ -745,7 +745,7 @@ proc typeSectionRightSidePass(c: PContext, n: PNode) =
       var t = semTypeNode(c, a.sons[2], s.typ)
       if s.typ == nil:
         s.typ = t
-      elif t != s.typ:
+      elif t != s.typ and (s.typ == nil or s.typ.kind != tyAlias):
         # this can happen for e.g. tcan_alias_specialised_generic:
         assignType(s.typ, t)
         #debug s.typ
@@ -804,8 +804,9 @@ proc typeSectionFinalPass(c: PContext, n: PNode) =
         assert t != nil
         if t.kind in {tyObject, tyEnum, tyDistinct}:
           assert s.typ != nil
-          assignType(s.typ, t)
-          s.typ.id = t.id     # same id
+          if s.typ.kind != tyAlias:
+            assignType(s.typ, t)
+            s.typ.id = t.id     # same id
       checkConstructedType(s.info, s.typ)
       if s.typ.kind in {tyObject, tyTuple} and not s.typ.n.isNil:
         checkForMetaFields(s.typ.n)

compiler/semtypes.nim

@@ -1152,6 +1152,13 @@ proc semProcTypeWithScope(c: PContext, n: PNode,
     when useEffectSystem: setEffectsForProcType(result, n.sons[1])
   closeScope(c)
 
+proc maybeAliasType(c: PContext; typeExpr, prev: PType): PType =
+  if typeExpr.kind in {tyObject, tyEnum, tyDistinct} and prev != nil:
+    result = newTypeS(tyAlias, c)
+    result.rawAddSon typeExpr
+    result.sym = prev.sym
+    assignType(prev, result)
+
 proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
   result = nil
   if gCmd == cmdIdeTools: suggestExpr(c, n)
@@ -1267,15 +1274,18 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     of mTuple: result = semTuple(c, n, prev)
     else: result = semGeneric(c, n, s, prev)
   of nkDotExpr:
-    var typeExpr = semExpr(c, n)
+    let typeExpr = semExpr(c, n)
     if typeExpr.typ.kind != tyTypeDesc:
       localError(n.info, errTypeExpected)
       result = errorType(c)
     else:
       result = typeExpr.typ.base
       if result.isMetaType:
-        var preprocessed = semGenericStmt(c, n)
+        let preprocessed = semGenericStmt(c, n)
         result = makeTypeFromExpr(c, preprocessed.copyTree)
+      else:
+        let alias = maybeAliasType(c, result, prev)
+        if alias != nil: result = alias
   of nkIdent, nkAccQuoted:
     var s = semTypeIdent(c, n)
     if s.typ == nil:
@@ -1287,16 +1297,23 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     elif prev == nil:
       result = s.typ
     else:
-      assignType(prev, s.typ)
-      # bugfix: keep the fresh id for aliases to integral types:
-      if s.typ.kind notin {tyBool, tyChar, tyInt..tyInt64, tyFloat..tyFloat128,
-                           tyUInt..tyUInt64}:
-        prev.id = s.typ.id
-      result = prev
+      let alias = maybeAliasType(c, s.typ, prev)
+      if alias != nil:
+        result = alias
+      else:
+        assignType(prev, s.typ)
+        # bugfix: keep the fresh id for aliases to integral types:
+        if s.typ.kind notin {tyBool, tyChar, tyInt..tyInt64, tyFloat..tyFloat128,
+                             tyUInt..tyUInt64}:
+          prev.id = s.typ.id
+        result = prev
   of nkSym:
     if n.sym.kind == skType and n.sym.typ != nil:
       var t = n.sym.typ
-      if prev == nil:
+      let alias = maybeAliasType(c, t, prev)
+      if alias != nil:
+        result = alias
+      elif prev == nil:
         result = t
       else:
         assignType(prev, t)

compiler/sighashes.nim

@@ -126,8 +126,6 @@ proc hashType(c: var MD5Context, t: PType; flags: set[ConsiderFlag]) =
     c &= "\254"
     return
 
-  c &= char(t.kind)
-
   case t.kind
   of tyGenericInst:
     var x = t.lastSon
@@ -148,9 +146,14 @@ proc hashType(c: var MD5Context, t: PType; flags: set[ConsiderFlag]) =
     else:
       c.hashSym(t.sym)
     return
+  of tyAlias:
+    c.hashType t.lastSon, flags
+    return
   else:
     discard
 
+  c &= char(t.kind)
+
   case t.kind
   of tyObject, tyEnum:
     # Every cyclic type in Nim need to be constructed via some 't.sym', so this
@@ -159,7 +162,7 @@ proc hashType(c: var MD5Context, t: PType; flags: set[ConsiderFlag]) =
       c.hashSym(t.sym)
     else:
       lowlevel(t.id)
-  of tyRef, tyPtr, tyGenericBody, tyAlias:
+  of tyRef, tyPtr, tyGenericBody:
     c.hashType t.lastSon, flags
   of tyUserTypeClass:
     if t.sym != nil and t.sym.owner != nil:

compiler/types.nim

@@ -398,7 +398,7 @@ proc rangeToStr(n: PNode): string =
 
 const
   typeToStr: array[TTypeKind, string] = ["None", "bool", "Char", "empty",
-    "Array Constructor [$1]", "nil", "untyped", "typed", "typeDesc",
+    "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",