fixes #1915

6 files changed, 29 insertions, 9 deletions

diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 4a3be0027..2d3cf562b 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -1977,7 +1977,9 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     of skParam:
       if sym.loc.r == nil or sym.loc.t == nil:
         #echo "FAILED FOR PRCO ", p.prc.name.s
-        internalError(n.info, "expr: param not init " & sym.name.s & "_" & $sym.id)
+        #debug p.prc.typ.n
+        #echo renderTree(p.prc.ast, {renderIds})
+        internalError(n.info, "expr: param not init " & sym.name.s & "_" & $sym.id)          
       putLocIntoDest(p, d, sym.loc)
     else: internalError(n.info, "expr(" & $sym.kind & "); unknown symbol")
   of nkNilLit:
diff --git a/compiler/evaltempl.nim b/compiler/evaltempl.nim
index 78cc691c0..946be68f8 100644
--- a/compiler/evaltempl.nim
+++ b/compiler/evaltempl.nim
@@ -29,7 +29,7 @@ proc evalTemplateAux(templ, actual: PNode, c: var TemplCtx, result: PNode) =
   of nkSym:
     var s = templ.sym
     if s.owner.id == c.owner.id:
-      if s.kind == skParam:
+      if s.kind == skParam and sfGenSym notin s.flags:
         let x = actual.sons[s.position]
         if x.kind == nkArgList:
           for y in items(x): result.add(y)
diff --git a/compiler/semdata.nim b/compiler/semdata.nim
index 623f9b633..bb82db292 100644
--- a/compiler/semdata.nim
+++ b/compiler/semdata.nim
@@ -35,6 +35,7 @@ type
     inTryStmt*: int           # whether we are in a try statement; works also
                               # in standalone ``except`` and ``finally``
     next*: PProcCon           # used for stacking procedure contexts
+    wasForwarded*: bool       # whether the current proc has a separate header
   
   TInstantiationPair* = object
     genericSym*: PSym
diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index f9889eee1..a3ae0263d 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -109,9 +109,16 @@ proc semSym(c: PContext, n: PNode, s: PSym, flags: TExprFlags): PNode =
     # if a proc accesses a global variable, it is not side effect free:
     if sfGlobal in s.flags:
       incl(c.p.owner.flags, sfSideEffect)
-    elif s.kind == skParam and s.typ.kind == tyStatic and s.typ.n != nil:
-      # XXX see the hack in sigmatch.nim ...
-      return s.typ.n
+    elif s.kind == skParam:
+      if s.typ.kind == tyStatic and s.typ.n != nil:
+        # XXX see the hack in sigmatch.nim ...
+        return s.typ.n
+      elif sfGenSym in s.flags and c.p.wasForwarded:
+        # gensym'ed parameters that nevertheless have been forward declared
+        # need a special fixup:
+        let realParam = c.p.owner.typ.n[s.position+1]
+        internalAssert realParam.kind == nkSym and realParam.sym.kind == skParam
+        return newSymNode(c.p.owner.typ.n[s.position+1].sym, n.info)
     result = newSymNode(s, n.info)
     # We cannot check for access to outer vars for example because it's still
     # not sure the symbol really ends up being used:
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 44f14afd8..3b90337e5 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -982,7 +982,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
   # process parameters:
   if n.sons[paramsPos].kind != nkEmpty:
     semParamList(c, n.sons[paramsPos], gp, s)
-    if sonsLen(gp) > 0: 
+    if sonsLen(gp) > 0:
       if n.sons[genericParamsPos].kind == nkEmpty:
         # we have a list of implicit type parameters:
         n.sons[genericParamsPos] = gp
@@ -1049,6 +1049,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
     if n.sons[genericParamsPos].kind == nkEmpty or usePseudoGenerics:
       if not usePseudoGenerics: paramsTypeCheck(c, s.typ)
       pushProcCon(c, s)
+      c.p.wasForwarded = proto != nil
       maybeAddResult(c, s, n)
       if sfImportc notin s.flags:
         # no semantic checking for importc:
diff --git a/compiler/semtempl.nim b/compiler/semtempl.nim
index 81e4f2463..e2c46d3ab 100644
--- a/compiler/semtempl.nim
+++ b/compiler/semtempl.nim
@@ -127,7 +127,7 @@ proc getIdentNode(c: var TemplCtx, n: PNode): PNode =
 
 proc isTemplParam(c: TemplCtx, n: PNode): bool {.inline.} =
   result = n.kind == nkSym and n.sym.kind == skParam and
-           n.sym.owner == c.owner
+           n.sym.owner == c.owner and sfGenSym notin n.sym.flags
 
 proc semTemplBody(c: var TemplCtx, n: PNode): PNode
 
@@ -246,8 +246,8 @@ proc semRoutineInTemplBody(c: var TemplCtx, n: PNode, k: TSymKind): PNode =
     n.sons[i] = semTemplBody(c, n.sons[i])
   closeScope(c)
 
-proc semTemplSomeDecl(c: var TemplCtx, n: PNode, symKind: TSymKind) =
-  for i in countup(0, sonsLen(n) - 1):
+proc semTemplSomeDecl(c: var TemplCtx, n: PNode, symKind: TSymKind; start=0) =
+  for i in countup(start, sonsLen(n) - 1):
     var a = n.sons[i]
     if a.kind == nkCommentStmt: continue
     if (a.kind != nkIdentDefs) and (a.kind != nkVarTuple): illFormedAst(a)
@@ -348,6 +348,10 @@ proc semTemplBody(c: var TemplCtx, n: PNode): PNode =
       a.sons[L-1] = semTemplBodyScope(c, a.sons[L-1])
   of nkVarSection: semTemplSomeDecl(c, n, skVar)
   of nkLetSection: semTemplSomeDecl(c, n, skLet)
+  of nkFormalParams:
+    checkMinSonsLen(n, 1)
+    n.sons[0] = semTemplBody(c, n.sons[0])
+    semTemplSomeDecl(c, n, skParam, 1)
   of nkConstSection:
     for i in countup(0, sonsLen(n) - 1): 
       var a = n.sons[i]
@@ -485,6 +489,11 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
   # process parameters:
   if n.sons[paramsPos].kind != nkEmpty:
     semParamList(c, n.sons[paramsPos], gp, s)
+    # a template's parameters are not gensym'ed even if that was originally the
+    # case as we determine whether it's a template parameter in the template
+    # body by the absense of the skGenSym flag:
+    for i in 1 .. s.typ.n.len-1:
+      s.typ.n.sons[i].sym.flags.excl sfGenSym
     if sonsLen(gp) > 0:
       if n.sons[genericParamsPos].kind == nkEmpty:
         # we have a list of implicit type parameters: