[clang] [analyzer] Avoid a crash in a debug printout function (PR #79446)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-static-analyzer-1

Author: None (NagyDonat)

<details>
<summary>Changes</summary>

Previously the function `RangeConstraintManager::printValue()` crashed when it encountered an empty rangeset (because `RangeSet::getBitwidth()` and `RangeSet::isUnsigned()` assert that the rangeset is not empty). This commit adds a special case that avoids this behavior.

As `printValue()` is only used by the checker debug.ExprInspection (and during manual debugging), the impacts of this commit are very limited.

---
Full diff: https://github.com/llvm/llvm-project/pull/79446.diff


1 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp (+6-2) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
index 25d066c4652f2b..cc1cad1e002cdf 100644
--- a/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp
@@ -3270,8 +3270,12 @@ void RangeConstraintManager::printJson(raw_ostream &Out, ProgramStateRef State,
 void RangeConstraintManager::printValue(raw_ostream &Out, ProgramStateRef State,
                                         SymbolRef Sym) {
   const RangeSet RS = getRange(State, Sym);
-  Out << RS.getBitWidth() << (RS.isUnsigned() ? "u:" : "s:");
-  RS.dump(Out);
+  if (RS.isEmpty()) {
+    Out << "<empty rangeset>";
+  } else {
+    Out << RS.getBitWidth() << (RS.isUnsigned() ? "u:" : "s:");
+    RS.dump(Out);
+  }
 }
 
 static std::string toString(const SymbolRef &Sym) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/79446