fixes #5417

compiler/ccgstmts.nim

@@ -540,7 +540,7 @@ proc genBreakStmt(p: BProc, t: PNode) =
     # named break?
     assert(t.sons[0].kind == nkSym)
     var sym = t.sons[0].sym
-    assert(sym.loc.k == locOther)
+    doAssert(sym.loc.k == locOther)
     idx = sym.position-1
   else:
     # an unnamed 'break' can only break a loop after 'transf' pass:

compiler/semexprs.nim

@@ -2107,7 +2107,7 @@ proc semBlock(c: PContext, n: PNode): PNode =
     var labl = newSymG(skLabel, n.sons[0], c)
     if sfGenSym notin labl.flags:
       addDecl(c, labl)
-      n.sons[0] = newSymNode(labl, n.sons[0].info)
+    n.sons[0] = newSymNode(labl, n.sons[0].info)
     suggestSym(n.sons[0].info, labl)
     styleCheckDef(labl)
   n.sons[1] = semExpr(c, n.sons[1])

compiler/semstmts.nim

@@ -30,6 +30,7 @@ proc semBreakOrContinue(c: PContext, n: PNode): PNode =
       of nkIdent: s = lookUp(c, n.sons[0])
       of nkSym: s = n.sons[0].sym
       else: illFormedAst(n)
+      s = getGenSym(c, s)
       if s.kind == skLabel and s.owner.id == c.p.owner.id:
         var x = newSymNode(s)
         x.info = n.info

compiler/semtempl.nim

@@ -384,11 +384,13 @@ proc semTemplBody(c: var TemplCtx, n: PNode): PNode =
     checkSonsLen(n, 2)
     openScope(c)
     if n.sons[0].kind != nkEmpty:
-      # labels are always 'gensym'ed:
-      let s = newGenSym(skLabel, n.sons[0], c)
-      addPrelimDecl(c.c, s)
-      styleCheckDef(s)
-      n.sons[0] = newSymNode(s, n.sons[0].info)
+      addLocalDecl(c, n.sons[0], skLabel)
+      when false:
+        # labels are always 'gensym'ed:
+        let s = newGenSym(skLabel, n.sons[0], c)
+        addPrelimDecl(c.c, s)
+        styleCheckDef(s)
+        n.sons[0] = newSymNode(s, n.sons[0].info)
     n.sons[1] = semTemplBody(c, n.sons[1])
     closeScope(c)
   of nkTryStmt:

tests/template/tgensym_label.nim

@@ -0,0 +1,18 @@
+
+# bug #5417
+import macros
+
+macro genBody: untyped =
+  let sbx = genSym(nskLabel, "test")
+  when true:
+    result = quote do:
+      block `sbx`:
+        break `sbx`
+  else:
+    template foo(s1, s2) =
+      block s1:
+        break s2
+    result = getAst foo(sbx, sbx)
+
+proc test() =
+  genBody()