From 4e4d466d060f9b55cb2adb3ad02e212281df4962 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Sun, 5 Nov 2017 16:53:05 +0100
Subject: [PATCH] minor breaking change: for loop bodies now get their own
 scope

---
 changelog.md          | 8 ++++++++
 compiler/semgnrc.nim  | 2 ++
 compiler/semstmts.nim | 2 ++
 compiler/semtempl.nim | 2 ++
 4 files changed, 14 insertions(+)

diff --git a/changelog.md b/changelog.md
index 5947c49e5..7aa52ece2 100644
--- a/changelog.md
+++ b/changelog.md
@@ -41,6 +41,14 @@
   what to return if the environment variable does not exist.
 - Removed PDCurses wrapper from the stdlib and published it as a separate
   Nimble package.
+- Bodies of ``for`` loops now get their own scope:
+
+.. code-block:: nim
+  # now compiles:
+  for i in 0..4:
+    let i = i + 1
+    echo i
+
 - The parsing rules of ``if`` expressions were changed so that multiple
   statements are allowed in the branches. We found few code examples that
   now fail because of this change, but here is one:
diff --git a/compiler/semgnrc.nim b/compiler/semgnrc.nim
index 3cdb68df6..e28a7851f 100644
--- a/compiler/semgnrc.nim
+++ b/compiler/semgnrc.nim
@@ -335,8 +335,10 @@ proc semGenericStmt(c: PContext, n: PNode,
     n.sons[L - 2] = semGenericStmt(c, n.sons[L-2], flags, ctx)
     for i in countup(0, L - 3):
       addTempDecl(c, n.sons[i], skForVar)
+    openScope(c)
     n.sons[L - 1] = semGenericStmt(c, n.sons[L-1], flags, ctx)
     closeScope(c)
+    closeScope(c)
   of nkBlockStmt, nkBlockExpr, nkBlockType:
     checkSonsLen(n, 2)
     openScope(c)
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 540ef4c07..80fad3f23 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -697,7 +697,9 @@ proc semForVars(c: PContext, n: PNode): PNode =
       if sfGenSym notin v.flags and not isDiscardUnderscore(v):
         addForVarDecl(c, v)
   inc(c.p.nestedLoopCounter)
+  openScope(c)
   n.sons[length-1] = semStmt(c, n.sons[length-1])
+  closeScope(c)
   dec(c.p.nestedLoopCounter)
 
 proc implicitIterator(c: PContext, it: string, arg: PNode): PNode =
diff --git a/compiler/semtempl.nim b/compiler/semtempl.nim
index 426290c78..1c9d8271a 100644
--- a/compiler/semtempl.nim
+++ b/compiler/semtempl.nim
@@ -366,8 +366,10 @@ proc semTemplBody(c: var TemplCtx, n: PNode): PNode =
     n.sons[L-2] = semTemplBody(c, n.sons[L-2])
     for i in countup(0, L - 3):
       addLocalDecl(c, n.sons[i], skForVar)
+    openScope(c)
     n.sons[L-1] = semTemplBody(c, n.sons[L-1])
     closeScope(c)
+    closeScope(c)
   of nkBlockStmt, nkBlockExpr, nkBlockType:
     checkSonsLen(n, 2)
     openScope(c)