From b6a8dcd922efef74fd956c06ebdb769d249a475b Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Mon, 27 May 2024 20:13:18 +0800
Subject: [PATCH] fixes #22852; fixes #23435; fixes #23645; SIGSEGV when
 slicing string or seq[T] with index out of range (#23279)

follow up https://github.com/nim-lang/Nim/pull/23013

fixes #22852
fixes #23435
fixes #23645

reports rangeDefect correctly

```nim
/workspaces/Nim/test9.nim(1) test9
/workspaces/Nim/lib/system/indices.nim(116) []
/workspaces/Nim/lib/system/fatal.nim(53) sysFatal
Error: unhandled exception: value out of range: -2 notin 0 .. 9223372036854775807 [RangeDefect]
```

(cherry picked from commit c615828ccb2b309ac03aab93d94b40af6b4079ff)
---
 compiler/cgen.nim | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index 14b0c1a341..d1e167c35f 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -1063,7 +1063,11 @@ proc allPathsAsgnResult(p: BProc; n: PNode): InitResultEnum =
       if result != Unknown: return result
   of nkAsgn, nkFastAsgn, nkSinkAsgn:
     if n[0].kind == nkSym and n[0].sym.kind == skResult:
-      if not containsResult(n[1]): result = InitSkippable
+      if not containsResult(n[1]):
+        if allPathsAsgnResult(p, n[1]) == InitRequired:
+          result = InitRequired
+        else:
+          result = InitSkippable
       else: result = InitRequired
     elif containsResult(n):
       result = InitRequired
@@ -1141,6 +1145,10 @@ proc allPathsAsgnResult(p: BProc; n: PNode): InitResultEnum =
         allPathsInBranch(n[i])
   of nkRaiseStmt:
     result = InitRequired
+  of nkChckRangeF, nkChckRange64, nkChckRange:
+    # TODO: more checks might need to be covered like overflow, indexDefect etc.
+    # bug #22852
+    result = InitRequired
   else:
     for i in 0..<n.safeLen:
       allPathsInBranch(n[i])