fixes #1713

compiler/ast.nim

@@ -938,7 +938,7 @@ const
   genericParamsPos* = 2
   paramsPos* = 3
   pragmasPos* = 4
-  optimizedCodePos* = 5  # will be used for exception tracking
+  miscPos* = 5  # used for undocumented and hacky stuff
   bodyPos* = 6       # position of body; use rodread.getBody() instead!
   resultPos* = 7
   dispatcherPos* = 8 # caution: if method has no 'result' it can be position 7!

compiler/renderer.nim

@@ -712,7 +712,11 @@ proc gproc(g: var TSrcGen, n: PNode) =
     gpattern(g, n.sons[patternPos])
   let oldCheckAnon = g.checkAnon
   g.checkAnon = true
-  gsub(g, n.sons[genericParamsPos])
+  if renderNoBody in g.flags and n[miscPos].kind != nkEmpty and
+      n[miscPos][1].kind != nkEmpty:
+    gsub(g, n[miscPos][1])
+  else:
+    gsub(g, n.sons[genericParamsPos])
   g.checkAnon = oldCheckAnon
   gsub(g, n.sons[paramsPos])
   gsub(g, n.sons[pragmasPos])

compiler/semcall.nim

@@ -129,7 +129,11 @@ proc notFoundError*(c: PContext, n: PNode, errors: CandidateErrors) =
   add(result, ')')
   var candidates = ""
   for err in errors:
-    add(candidates, err.getProcHeader(prefer))
+    if err.kind in routineKinds and err.ast != nil:
+      add(candidates, renderTree(err.ast,
+            {renderNoBody, renderNoComments,renderNoPragmas}))
+    else:
+      add(candidates, err.getProcHeader(prefer))
     add(candidates, "\n")
   if candidates != "":
     add(result, "\n" & msgKindToString(errButExpected) & "\n" & candidates)

compiler/semstmts.nim

@@ -929,6 +929,17 @@ proc semProcAnnotation(c: PContext, prc: PNode;
       pragma(c, result[namePos].sym, result[pragmasPos], validPragmas)
     return
 
+proc setGenericParamsMisc(c: PContext; n: PNode): PNode =
+  let orig = n.sons[genericParamsPos]
+  # we keep the original params around for better error messages, see
+  # issue https://github.com/nim-lang/Nim/issues/1713
+  result = semGenericParamList(c, orig)
+  if n.sons[miscPos].kind == nkEmpty:
+    n.sons[miscPos] = newTree(nkBracket, ast.emptyNode, orig)
+  else:
+    n.sons[miscPos].sons[1] = orig
+  n.sons[genericParamsPos] = result
+
 proc semLambda(c: PContext, n: PNode, flags: TExprFlags): PNode =
   # XXX semProcAux should be good enough for this now, we will eventually
   # remove semLambda
@@ -947,8 +958,7 @@ proc semLambda(c: PContext, n: PNode, flags: TExprFlags): PNode =
   openScope(c)
   var gp: PNode
   if n.sons[genericParamsPos].kind != nkEmpty:
-    n.sons[genericParamsPos] = semGenericParamList(c, n.sons[genericParamsPos])
+    gp = setGenericParamsMisc(c, n)
-    gp = n.sons[genericParamsPos]
   else:
     gp = newNodeI(nkGenericParams, n.info)
 
@@ -1170,8 +1180,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
   openScope(c)
   var gp: PNode
   if n.sons[genericParamsPos].kind != nkEmpty:
-    n.sons[genericParamsPos] = semGenericParamList(c, n.sons[genericParamsPos])
+    gp = setGenericParamsMisc(c, n)
-    gp = n.sons[genericParamsPos]
   else:
     gp = newNodeI(nkGenericParams, n.info)
   # process parameters:

compiler/vmgen.nim

@@ -1887,8 +1887,8 @@ proc optimizeJumps(c: PCtx; start: int) =
     else: discard
 
 proc genProc(c: PCtx; s: PSym): int =
-  let x = s.ast.sons[optimizedCodePos]
+  var x = s.ast.sons[miscPos]
-  if x.kind == nkEmpty:
+  if x.kind == nkEmpty or x[0].kind == nkEmpty:
     #if s.name.s == "outterMacro" or s.name.s == "innerProc":
     #  echo "GENERATING CODE FOR ", s.name.s
     let last = c.code.len-1
@@ -1899,7 +1899,11 @@ proc genProc(c: PCtx; s: PSym): int =
       c.debug.setLen(last)
     #c.removeLastEof
     result = c.code.len+1 # skip the jump instruction
-    s.ast.sons[optimizedCodePos] = newIntNode(nkIntLit, result)
+    if x.kind == nkEmpty:
+      x = newTree(nkBracket, newIntNode(nkIntLit, result), ast.emptyNode)
+    else:
+      x.sons[0] = newIntNode(nkIntLit, result)
+    s.ast.sons[miscPos] = x
     # thanks to the jmp we can add top level statements easily and also nest
     # procs easily:
     let body = s.getBody
@@ -1934,4 +1938,4 @@ proc genProc(c: PCtx; s: PSym): int =
     c.prc = oldPrc
   else:
     c.prc.maxSlots = s.offset
-    result = x.intVal.int
+    result = x[0].intVal.int