Allow void macro result (#11286)

* allow void macro result
* add test for void macro result type

changelog.md

@@ -36,8 +36,12 @@
 
 - Compile time checks for integer and float conversions are now stricter. For example, `const x = uint32(-1)` now gives a compile time error instead of being equivalent to `const x = 0xFFFFFFFF'u32`.
 
-- A bug allowed ``macro foo(): int = 123`` to compile even though a
+- Using `typed` as the result type in templates/macros now means
-  macros has to return a ``NimNode``. This has been fixed.
+  "expression with a type". The old meaning of `typed` is preserved
+  as `void` or no result type at all.
+
+- A bug allowed `macro foo(): int = 123` to compile even though a
+  macros has to return a `NimNode`. This has been fixed.
 
 #### Breaking changes in the standard library
 

compiler/extccomp.nim

@@ -759,7 +759,7 @@ proc getLinkCmd(conf: ConfigRef; output: AbsoluteFile,
 template getLinkCmd(conf: ConfigRef; output: AbsoluteFile, objfiles: string): string =
   getLinkCmd(conf, output, objfiles, optGenDynLib in conf.globalOptions)
 
-template tryExceptOSErrorMessage(conf: ConfigRef; errorPrefix: string = "", body: untyped): typed =
+template tryExceptOSErrorMessage(conf: ConfigRef; errorPrefix: string = "", body: untyped) =
   try:
     body
   except OSError:

compiler/sem.nim

@@ -407,12 +407,11 @@ proc semAfterMacroCall(c: PContext, call, macroResult: PNode,
   else:
     case s.typ.sons[0].kind
     of tyUntyped:
-      # BUGFIX: we cannot expect a type here, because module aliases would not
+      # Not expecting a type here allows templates like in ``tmodulealias.in``.
-      # work then (see the ``tmodulealias`` test)
-      # semExprWithType(c, result)
       result = semExpr(c, result, flags)
     of tyTyped:
-      result = semStmt(c, result, flags)
+      # More restrictive version.
+      result = semExprWithType(c, result, flags)
     of tyTypeDesc:
       if result.kind == nkStmtList: result.kind = nkStmtListType
       var typ = semTypeNode(c, result, nil)

compiler/semexprs.nim

@@ -1985,7 +1985,7 @@ proc semQuoteAst(c: PContext, n: PNode): PNode =
 
   if ids.len > 0:
     dummyTemplate.sons[paramsPos] = newNodeI(nkFormalParams, n.info)
-    dummyTemplate[paramsPos].add getSysSym(c.graph, n.info, "typed").newSymNode # return type
+    dummyTemplate[paramsPos].add getSysSym(c.graph, n.info, "untyped").newSymNode # return type
     ids.add getSysSym(c.graph, n.info, "untyped").newSymNode # params type
     ids.add c.graph.emptyNode # no default value
     dummyTemplate[paramsPos].add newNode(nkIdentDefs, n.info, ids)

compiler/semstmts.nim

@@ -1356,7 +1356,7 @@ proc semBorrow(c: PContext, n: PNode, s: PSym) =
     localError(c.config, n.info, errNoSymbolToBorrowFromFound)
 
 proc addResult(c: PContext, t: PType, info: TLineInfo, owner: TSymKind) =
-  if t != nil:
+  if owner == skMacro or t != nil:
     var s = newSym(skResult, getIdent(c.cache, "result"), getCurrOwner(c), info)
     s.typ = t
     incl(s.flags, sfUsed)
@@ -1550,17 +1550,17 @@ proc activate(c: PContext, n: PNode) =
       discard
 
 proc maybeAddResult(c: PContext, s: PSym, n: PNode) =
-  if s.typ.sons[0] != nil and not isInlineIterator(s):
-    let resultType =
   if s.kind == skMacro:
-        if s.typ.sons[0].kind == tyTypeDesc:
+    let resultType =
+      if s.typ.sons[0] != nil and s.typ.sons[0].kind == tyTypeDesc:
         s.typ.sons[0]
       else:
         sysTypeFromName(c.graph, n.info, "NimNode")
-      else:
-        s.typ.sons[0]
     addResult(c, resultType, n.info, s.kind)
     addResultNode(c, n)
+  elif s.typ.sons[0] != nil and not isInlineIterator(s):
+    addResult(c, s.typ.sons[0], n.info, s.kind)
+    addResultNode(c, n)
 
 proc canonType(c: PContext, t: PType): PType =
   if t.kind == tySequence:
@@ -1888,7 +1888,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
           # context as it may even be evaluated in 'system.compiles':
           trackProc(c, s, s.ast[bodyPos])
       else:
-        if s.typ.sons[0] != nil and kind != skIterator:
+        if (s.typ.sons[0] != nil and kind != skIterator) or kind == skMacro:
           addDecl(c, newSym(skUnknown, getIdent(c.cache, "result"), nil, n.info))
 
         openScope(c)
@@ -2015,7 +2015,6 @@ proc semMacroDef(c: PContext, n: PNode): PNode =
     let param = t.n.sons[i].sym
     if param.typ.kind != tyUntyped: allUntyped = false
   if allUntyped: incl(s.flags, sfAllUntyped)
-  if t.sons[0] == nil: localError(c.config, n.info, "macro needs a return type")
   if n.sons[bodyPos].kind == nkEmpty:
     localError(c.config, n.info, errImplOfXexpected % s.name.s)
 

compiler/semtempl.nim

@@ -606,11 +606,6 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
       if n.sons[genericParamsPos].kind == nkEmpty:
         # we have a list of implicit type parameters:
         n.sons[genericParamsPos] = gp
-    # no explicit return type? -> use tyTyped
-    if n.sons[paramsPos].sons[0].kind == nkEmpty:
-      # use ``stmt`` as implicit result type
-      s.typ.sons[0] = newTypeS(tyTyped, c)
-      s.typ.n.sons[0] = newNodeIT(nkType, n.info, s.typ.sons[0])
   else:
     s.typ = newTypeS(tyProc, c)
     # XXX why do we need tyTyped as a return type again?

compiler/semtypes.nim

@@ -855,6 +855,7 @@ proc findEnforcedStaticType(t: PType): PType =
   # This handles types such as `static[T] and Foo`,
   # which are subset of `static[T]`, hence they could
   # be treated in the same way
+  if t == nil: return nil
   if t.kind == tyStatic: return t
   if t.kind == tyAnd:
     for s in t.sons:
@@ -868,7 +869,7 @@ proc addParamOrResult(c: PContext, param: PSym, kind: TSymKind) =
       var a = copySym(param)
       a.typ = staticType.base
       addDecl(c, a)
-    elif param.typ.kind == tyTypeDesc:
+    elif param.typ != nil and param.typ.kind == tyTypeDesc:
       addDecl(c, param)
     else:
       # within a macro, every param has the type NimNode!
@@ -1194,6 +1195,18 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
   if n.sons[0].kind != nkEmpty:
     r = semTypeNode(c, n.sons[0], nil)
 
+  if r != nil and kind in {skMacro, skTemplate} and r.kind == tyTyped:
+    # XXX: To implement the propesed change in the warning, just
+    # delete this entire if block. The rest is (at least at time of
+    # writing this comment) already implemented.
+    let info = n.sons[0].info
+    const msg = "`typed` will change its meaning in future versions of Nim. " &
+                "`void` or no return type declaration at all has the same " &
+                "meaning as the current meaning of `typed` as return type " &
+                "declaration."
+    message(c.config, info, warnDeprecated, msg)
+    r = nil
+
   if r != nil:
     # turn explicit 'void' return type into 'nil' because the rest of the
     # compiler only checks for 'nil':

compiler/vm.nim

@@ -1104,7 +1104,7 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
         #echo "new pc ", newPc, " calling: ", prc.name.s
         var newFrame = PStackFrame(prc: prc, comesFrom: pc, next: tos)
         newSeq(newFrame.slots, prc.offset+ord(isClosure))
-        if not isEmptyType(prc.typ.sons[0]) or prc.kind == skMacro:
+        if not isEmptyType(prc.typ.sons[0]):
           putIntoReg(newFrame.slots[0], getNullValue(prc.typ.sons[0], prc.info, c.config))
         for i in 1 .. rc-1:
           newFrame.slots[i] = regs[rb+i]

lib/core/macros.nim

@@ -567,7 +567,7 @@ proc quote*(bl: typed, op = "``"): NimNode {.magic: "QuoteAst", noSideEffect.}
   ##
   ## .. code-block:: nim
   ##
-  ##   macro check(ex: untyped): typed =
+  ##   macro check(ex: untyped) =
   ##     # this is a simplified version of the check macro from the
   ##     # unittest module.
   ##

lib/pure/pegs.nim

@@ -572,7 +572,7 @@ when not useUnicode:
   proc isTitle(a: char): bool {.inline.} = return false
   proc isWhiteSpace(a: char): bool {.inline.} = return a in {' ', '\9'..'\13'}
 
-template matchOrParse(mopProc: untyped): typed =
+template matchOrParse(mopProc: untyped) =
   # Used to make the main matcher proc *rawMatch* as well as event parser
   # procs. For the former, *enter* and *leave* event handler code generators
   # are provided which just return *discard*.

lib/system/assertions.nim

@@ -71,7 +71,7 @@ template onFailedAssert*(msg, code: untyped): untyped {.dirty.} =
     let msg = msgIMPL
     code
 
-template doAssertRaises*(exception: typedesc, code: untyped): typed =
+template doAssertRaises*(exception: typedesc, code: untyped) =
   ## Raises ``AssertionError`` if specified ``code`` does not raise the
   ## specified exception. Example:
   ##

nimsuggest/tests/tsug_template.nim

@@ -8,5 +8,5 @@ $nimsuggest --tester $file
 >sug $1
 sug;;skMacro;;tsug_template.tmpb;;macro (){.noSideEffect, gcsafe, locks: 0.};;$file;;2;;6;;"";;0;;Prefix
 sug;;skConverter;;tsug_template.tmpc;;converter ();;$file;;3;;10;;"";;0;;Prefix
-sug;;skTemplate;;tsug_template.tmpa;;template (): typed;;$file;;1;;9;;"";;0;;Prefix
+sug;;skTemplate;;tsug_template.tmpa;;template ();;$file;;1;;9;;"";;0;;Prefix
 """

tests/ccgbugs/tnocodegen_for_compiletime.nim

@@ -1,7 +1,7 @@
 # bug #1679
 import macros, tables, hashes
 proc hash(v: NimNode): Hash = 4  # performance is for suckers
-macro test(body: untyped): typed =
+macro test(body: untyped) =
   var a = initCountTable[NimNode]()
   a.inc(body)
 

tests/fields/tfields.nim

@@ -46,7 +46,7 @@ block ttemplate:
   for name, value in (n: "v").fieldPairs:
     echo name
 
-  template wrapper: typed =
+  template wrapper(): void =
     for name, value in (n: "v").fieldPairs:
       echo name
   wrapper()

tests/lookups/test.nim

@@ -12,7 +12,7 @@ import unittest, macros
 
 # bug #4555
 
-macro memo(n: untyped): typed =
+macro memo(n: untyped) =
   result = n
 
 proc fastFib(n: int): int {.memo.} = 40

tests/macros/tcomplexecho.nim

@@ -32,7 +32,7 @@ proc foo(): seq[NimNode] {.compiletime.} =
   result.add test()
   result.add parseExpr("echo(5+56)")
 
-macro bar(): typed =
+macro bar() =
   result = newNimNode(nnkStmtList)
   let x = foo()
   for xx in x:

tests/macros/tgettypeinst.nim

@@ -22,7 +22,7 @@ proc symToIdent(x: NimNode): NimNode =
         result.add symToIdent(c)
 
 # check getTypeInst and getTypeImpl for given symbol x
-macro testX(x,inst0: typed; recurse: static[bool]; implX: typed): typed =
+macro testX(x,inst0: typed; recurse: static[bool]; implX: typed) =
   # check that getTypeInst(x) equals inst0
   let inst = x.getTypeInst
   let instr = inst.symToIdent.treeRepr

tests/macros/tmacro5.nim

@@ -38,7 +38,7 @@ macro importImpl_forward(name, returns: untyped): untyped =
   decls.add res
   echo(repr(res))
 
-macro importImpl(name, returns, body: untyped): typed =
+macro importImpl(name, returns, body: untyped) =
   #var res = getAST(importImpl_forward(name, returns))
   discard getAST(importImpl_forward(name, returns))
   var res = copyNimTree(decls[decls.high])
@@ -46,7 +46,7 @@ macro importImpl(name, returns, body: untyped): typed =
   echo repr(res)
   impls.add res
 
-macro okayy: typed =
+macro okayy() =
   result = newNimNode(nnkStmtList)
   for node in decls: result.add node
   for node in impls: result.add node

tests/macros/tmacro6.nim

@@ -0,0 +1,75 @@
+discard """
+errormsg: "expression '123' is of type 'int literal(123)' and has to be discarded"
+line: 71
+"""
+
+import macros
+
+proc foo(a,b,c: int): int =
+  result += a
+  result += b
+  result += c
+
+macro bar(a,b,c: int): int =
+  result = newCall(ident"echo")
+  result.add a
+  result.add b
+  result.add c
+
+macro baz(a,b,c: int): int =
+  let stmt = nnkStmtListExpr.newTree()
+  stmt.add newCall(ident"echo", a)
+  stmt.add newCall(ident"echo", b)
+  stmt.add newCall(ident"echo", c)
+  stmt.add newLit(123)
+  return c
+
+# test no result type with explicit return
+
+macro baz2(a,b,c: int) =
+  let stmt = nnkStmtListExpr.newTree()
+  stmt.add newCall(ident"echo", a)
+  stmt.add newCall(ident"echo", b)
+  stmt.add newCall(ident"echo", c)
+  return stmt
+
+# test explicit void type with explicit return
+
+macro baz3(a,b,c: int): void =
+  let stmt = nnkStmtListExpr.newTree()
+  stmt.add newCall(ident"echo", a)
+  stmt.add newCall(ident"echo", b)
+  stmt.add newCall(ident"echo", c)
+  return stmt
+
+# test no result type with result variable
+
+macro baz4(a,b,c: int) =
+  result = nnkStmtListExpr.newTree()
+  result.add newCall(ident"echo", a)
+  result.add newCall(ident"echo", b)
+  result.add newCall(ident"echo", c)
+
+# test explicit void type with result variable
+
+macro baz5(a,b,c: int): void =
+  let result = nnkStmtListExpr.newTree()
+  result.add newCall(ident"echo", a)
+  result.add newCall(ident"echo", b)
+  result.add newCall(ident"echo", c)
+
+macro foobar1(): int =
+  result = quote do:
+    echo "Hello World"
+    1337
+
+echo foobar1()
+
+# this should create an error message, because 123 has to be discarded.
+
+macro foobar2() =
+  result = quote do:
+    echo "Hello World"
+    123
+
+echo foobar2()

tests/macros/tmacrostmt.nim

@@ -18,9 +18,10 @@ case_token: inc i
 
 #bug #488
 
-macro foo: typed =
+macro foo() =
   var exp = newCall("whatwhat", newIntLitNode(1))
-  if compiles(getAst(exp)): return exp
+  if compiles(getAst(exp)):
+    return exp
   else: echo "Does not compute! (test OK)"
 
 foo()
@@ -37,7 +38,7 @@ proc `!!` (c: cstring): int =
 proc f(name: MyString): int =
   !! $ name
 
-macro repr_and_parse(fn: typed): typed =
+macro repr_and_parse(fn: typed) =
   let fn_impl = fn.getImpl
   fn_impl.name = genSym(nskProc, $fn_impl.name)
   echo fn_impl.repr
@@ -134,4 +135,3 @@ repr_and_parse(test_block)
 repr_and_parse(test_cond_stmtlist)
 repr_and_parse(t2)
 repr_and_parse(test_pure_enums)
-

tests/metatype/tmetatype_issues.nim

@@ -34,7 +34,7 @@ block t898:
 
 
 block t7528:
-  macro bar(n: untyped): typed =
+  macro bar(n: untyped) =
     result = newNimNode(nnkStmtList, n)
     result.add(newCall("write", newIdentNode("stdout"), n))
 

tests/template/template_various.nim

@@ -77,7 +77,7 @@ block generic_templates:
 block tgetast_typeliar:
   proc error(s: string) = quit s
 
-  macro assertOrReturn(condition: bool; message: string): typed =
+  macro assertOrReturn2(condition: bool; message: string) =
     var line = condition.lineInfo()
     result = quote do:
       block:
@@ -86,8 +86,10 @@ block tgetast_typeliar:
           return
 
   macro assertOrReturn(condition: bool): typed =
-    var message = condition.toStrLit()
+    var message : NimNode = newLit(condition.repr)
-    result = getAst assertOrReturn(condition, message)
+    # echo message
+    result = getAst assertOrReturn2(condition, message)
+    echo result.repr
 
   proc point(size: int16): tuple[x, y: int16] =
     # returns random point in square area with given `size`
@@ -245,7 +247,3 @@ block ttempl5:
 block templreturntype:
   template `=~` (a: int, b: int): bool = false
   var foo = 2 =~ 3
-
-
-
-

tests/vm/texcl.nim

@@ -18,7 +18,7 @@ proc initOpts(): set[nlOptions] =
 
 const cOpts = initOpts()
 
-macro nlo(): typed =
+macro nlo() =
   nlOpts.incl(nloNone)
   nlOpts.excl(nloDebug)
   result = newEmptyNode()

tests/vm/tstaticprintseq.nim

@@ -24,7 +24,7 @@ bb
 
 const s = @[1,2,3]
 
-macro foo: typed =
+macro foo() =
   for e in s:
     echo e
 
@@ -55,7 +55,7 @@ static:
   var m2: TData = data
   for x in m2.numbers: echo x
 
-macro ff(d: static[TData]): typed =
+macro ff(d: static[TData]) =
   for x in d.letters:
     echo x
 

tests/vm/ttouintconv.nim

@@ -20,7 +20,7 @@ nimout: '''
 
 #bug #2514
 
-macro foo(): typed =
+macro foo() =
   var x = 8'u8
   var y = 9'u16
   var z = 17'u32
@@ -58,7 +58,7 @@ macro foo(): typed =
   var zz = 0x7FFFFFFF'u32
   echo zz
 
-macro foo2(): typed =
+macro foo2() =
   var xx = 0x7FFFFFFFFFFFFFFF
   echo xx