1 files changed, 88 insertions, 0 deletions
diff --git a/compiler/procfind.nim b/compiler/procfind.nim
new file mode 100644
index 000000000..c2cc6e71f
--- /dev/null
+++ b/compiler/procfind.nim
@@ -0,0 +1,88 @@
+#
+#
+#           The Nim Compiler
+#        (c) Copyright 2013 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+# This module implements the searching for procs and iterators.
+# This is needed for proper handling of forward declarations.
+
+import
+  ast, astalgo, msgs, semdata, types, trees, lookups
+
+import std/strutils
+
+proc equalGenericParams(procA, procB: PNode): bool =
+  if procA.len != procB.len: return false
+  for i in 0..<procA.len:
+    if procA[i].kind != nkSym:
+      return false
+    if procB[i].kind != nkSym:
+      return false
+    let a = procA[i].sym
+    let b = procB[i].sym
+    if a.name.id != b.name.id or
+        not sameTypeOrNil(a.typ, b.typ, {ExactTypeDescValues}): return
+    if a.ast != nil and b.ast != nil:
+      if not exprStructuralEquivalent(a.ast, b.ast): return
+  result = true
+
+proc searchForProcAux(c: PContext, scope: PScope, fn: PSym): PSym =
+  const flags = {ExactGenericParams, ExactTypeDescValues,
+                 ExactConstraints, IgnoreCC}
+  var it: TIdentIter = default(TIdentIter)
+  result = initIdentIter(it, scope.symbols, fn.name)
+  while result != nil:
+    if result.kind == fn.kind: #and sameType(result.typ, fn.typ, flags):
+      case equalParams(result.typ.n, fn.typ.n)
+      of paramsEqual:
+        if (sfExported notin result.flags) and (sfExported in fn.flags):
+          let message = ("public implementation '$1' has non-public " &
+                         "forward declaration at $2") %
+                        [getProcHeader(c.config, result, getDeclarationPath = false), c.config$result.info]
+          localError(c.config, fn.info, message)
+        return
+      of paramsIncompatible:
+        localError(c.config, fn.info, "overloaded '$1' leads to ambiguous calls" % fn.name.s)
+        return
+      of paramsNotEqual:
+        discard
+    result = nextIdentIter(it, scope.symbols)
+
+proc searchForProc*(c: PContext, scope: PScope, fn: PSym): tuple[proto: PSym, comesFromShadowScope: bool] =
+  var scope = scope
+  result = (searchForProcAux(c, scope, fn), false)
+  while result.proto == nil and scope.isShadowScope:
+    scope = scope.parent
+    result.proto = searchForProcAux(c, scope, fn)
+    result.comesFromShadowScope = true
+
+when false:
+  proc paramsFitBorrow(child, parent: PNode): bool =
+    result = false
+    if child.len == parent.len:
+      for i in 1..<child.len:
+        var m = child[i].sym
+        var n = parent[i].sym
+        assert((m.kind == skParam) and (n.kind == skParam))
+        if not compareTypes(m.typ, n.typ, dcEqOrDistinctOf): return
+      if not compareTypes(child[0].typ, parent[0].typ,
+                          dcEqOrDistinctOf): return
+      result = true
+
+  proc searchForBorrowProc*(c: PContext, startScope: PScope, fn: PSym): PSym =
+    # Searches for the fn in the symbol table. If the parameter lists are suitable
+    # for borrowing the sym in the symbol table is returned, else nil.
+    var it: TIdentIter = default(TIdentIter)
+    for scope in walkScopes(startScope):
+      result = initIdentIter(it, scope.symbols, fn.Name)
+      while result != nil:
+        # watchout! result must not be the same as fn!
+        if (result.Kind == fn.kind) and (result.id != fn.id):
+          if equalGenericParams(result.ast[genericParamsPos],
+                                fn.ast[genericParamsPos]):
+            if paramsFitBorrow(fn.typ.n, result.typ.n): return
+        result = NextIdentIter(it, scope.symbols)