simplify asyncfutures, asyncmacro (#17633)

tests/async/tasyncintemplate.nim

@@ -1,6 +1,8 @@
 discard """
   output: '''
 42
+43
+43
 1
 2
 3
@@ -8,16 +10,30 @@ discard """
 '''
 """
 
+# xxx move to tests/async/tasyncintemplate.nim
 import asyncdispatch
 
-# bug #16159
-template foo() =
-  proc temp(): Future[int] {.async.} = return 42
-  proc tempVoid(): Future[void] {.async.} = echo await temp()
+block: # bug #16159
+  template foo() =
+    proc temp(): Future[int] {.async.} = return 42
+    proc tempVoid(): Future[void] {.async.} = echo await temp()
+  foo()
+  waitFor tempVoid()
 
-foo()
-waitFor tempVoid()
+block: # aliasing `void`
+  template foo() =
+    type Foo = void
+    proc temp(): Future[int] {.async.} = return 43
+    proc tempVoid(): Future[Foo] {.async.} = echo await temp()
+    proc tempVoid2() {.async.} = echo await temp()
+  foo()
+  waitFor tempVoid()
+  waitFor tempVoid2()
 
+block: # sanity check
+  template foo() =
+    proc bad(): int {.async.} = discard
+  doAssert not compiles(bad())
 
 block: # bug #16786
   block:

tests/errmsgs/tgcsafety.nim

@@ -6,7 +6,8 @@ tgcsafety.nim(30, 18) Error: type mismatch: got <AsyncHttpServer, Port, proc (re
 but expected one of:
 proc serve(server: AsyncHttpServer; port: Port;
            callback: proc (request: Request): Future[void] {.closure, gcsafe.};
-           address = ""; assumedDescriptorsPerRequest = -1): owned(Future[void])
+           address = ""; assumedDescriptorsPerRequest = -1): owned(
+    Future[void])
   first type mismatch at position: 3
   required type for callback: proc (request: Request): Future[system.void]{.closure, gcsafe.}
   but expression 'cb' is of type: proc (req: Request): Future[system.void]{.locks: <unknown>.}

tests/pragmas/tcustom_pragma.nim

@@ -262,6 +262,10 @@ block:
     doAssert input.treeRepr & "\n" == expectedRepr
     return input
 
+  macro expectedAstRepr(expectedRepr: static[string], input: untyped): untyped =
+    doAssert input.repr == expectedRepr
+    return input
+
   const procTypeAst = """
 ProcTy
   FormalParams
@@ -280,20 +284,10 @@ ProcTy
   static: doAssert Foo is proc(x: int): Future[void]
 
   const asyncProcTypeAst = """
-ProcTy
-  FormalParams
-    BracketExpr
-      Ident "Future"
-      Ident "void"
-    IdentDefs
-      Ident "s"
-      Ident "string"
-      Empty
-  Pragma
-"""
-
+proc (s: string): Future[void] {..}"""
+  # using expectedAst would show `OpenSymChoice` for Future[void], which is fragile.
   type
-    Bar = proc (s: string) {.async, expectedAst(asyncProcTypeAst).}
+    Bar = proc (s: string) {.async, expectedAstRepr(asyncProcTypeAst).}
 
   static: doAssert Bar is proc(x: string): Future[void]