From 558b46fde2db2215794336bbd08e411fee5240d7 Mon Sep 17 00:00:00 2001
From: Balazs Benics <benicsbalazs@gmail.com>
Date: Wed, 22 Mar 2023 08:43:09 +0100
Subject: [PATCH] [analyzer] Fix crashing getSValFromInitListExpr for nested
 initlists

In the following example, we will end up hitting the `llvm_unreachable()`:
https://godbolt.org/z/5sccc95Ec
```lang=C++
enum class E {};
const E glob[] = {{}};
void initlistWithinInitlist() {
  clang_analyzer_dump(glob[0]); // crashes at loading from `glob[0]`
}
```

We should just return `std::nullopt` instead for these cases.
It's better than crashing.

Reviewed By: xazax.hun

Differential Revision: https://reviews.llvm.org/D146538
---
 clang/lib/StaticAnalyzer/Core/RegionStore.cpp | 8 ++++++--
 clang/test/Analysis/initialization.cpp        | 7 +++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index 46948c12617c..49855305cecc 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -1849,8 +1849,12 @@ std::optional<SVal> RegionStoreManager::getSValFromInitListExpr(
     // Go to the nested initializer list.
     ILE = IL;
   }
-  llvm_unreachable(
-      "Unhandled InitListExpr sub-expressions or invalid offsets.");
+
+  assert(ILE);
+
+  // FIXME: Unhandeled InitListExpr sub-expression, possibly constructing an
+  //        enum?
+  return std::nullopt;
 }
 
 /// Returns an SVal, if possible, for the specified position in a string
diff --git a/clang/test/Analysis/initialization.cpp b/clang/test/Analysis/initialization.cpp
index e5b94ea7d0a2..e624ef5bae9e 100644
--- a/clang/test/Analysis/initialization.cpp
+++ b/clang/test/Analysis/initialization.cpp
@@ -249,3 +249,10 @@ void glob_array_parentheses1() {
   clang_analyzer_eval(glob_arr9[1][2] == 7); // expected-warning{{TRUE}}
   clang_analyzer_eval(glob_arr9[1][3] == 0); // expected-warning{{TRUE}}
 }
+
+enum class E {};
+const E glob[] = {{}};
+void initlistWithinInitlist() {
+  // no-crash
+  clang_analyzer_dump(glob[0]); // expected-warning-re {{reg_${{[0-9]+}}<enum E Element{glob,0 S64b,enum E}>}}
+}