[clang] [analyzer] Fix uninitialized base class with initializer list when ctor is not declared in the base class (#70464) (PR #70792)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Ella Ma (Snape3058)

<details>
<summary>Changes</summary>

When ctor is not declared in the base class, initializing the base class with the initializer list will not trigger a proper assignment of the base region, as a CXXConstructExpr doing that is not available in the AST.

This patch checks whether the init expr is an InitListExpr under a base initializer, and adds a binding if so.

---
Full diff: https://github.com/llvm/llvm-project/pull/70792.diff


2 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Core/ExprEngine.cpp (+9) 
- (added) clang/test/Analysis/issue-70464.cpp (+69) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 2e67fb953e45611..78dd1147ce1aa7c 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1222,6 +1222,15 @@ void ExprEngine::ProcessInitializer(const CFGInitializer CFGInit,
       PostInitializer PP(BMI, FieldLoc.getAsRegion(), stackFrame);
       evalBind(Tmp, Init, Pred, FieldLoc, InitVal, /*isInit=*/true, &PP);
     }
+  } else if (BMI->isBaseInitializer() && isa<InitListExpr>(Init)) {
+    // When the base class is initialized with an initialization list, there
+    // will not be a CXXConstructExpr to initialize the base region. Hence, we
+    // need to make the bind for it.
+    StoreManager &StoreMgr = State->getStateManager().getStoreManager();
+    SVal BaseLoc = StoreMgr.evalDerivedToBase(
+        thisVal, QualType(BMI->getBaseClass(), 0), BMI->isBaseVirtual());
+    SVal InitVal = State->getSVal(Init, stackFrame);
+    evalBind(Tmp, Init, Pred, BaseLoc, InitVal, true);
   } else {
     assert(BMI->isBaseInitializer() || BMI->isDelegatingInitializer());
     Tmp.insert(Pred);
diff --git a/clang/test/Analysis/issue-70464.cpp b/clang/test/Analysis/issue-70464.cpp
new file mode 100644
index 000000000000000..0acced7ae102cac
--- /dev/null
+++ b/clang/test/Analysis/issue-70464.cpp
@@ -0,0 +1,69 @@
+// Refer issue 70464 for more details.
+//
+// When the base class does not have a declared constructor, the base
+// initializer in the constructor of the derived class should use the given
+// initializer list to finish the initialization of the base class.
+//
+// Also testing base constructor and delegate constructor to make sure this
+// change will not break these two cases when a CXXConstructExpr is available.
+
+// RUN: %clang_analyze_cc1 %s -verify -analyzer-checker=core,debug.ExprInspection
+
+void clang_analyzer_dump(int);
+
+namespace init_list {
+
+struct foo {
+  int foox;
+};
+
+class bar : public foo {
+public:
+  bar() : foo{42} {
+    // The dereference to this->foox below should be initialized properly.
+    clang_analyzer_dump(this->foox); // expected-warning{{42 S32b}}
+  }
+};
+
+void entry() { bar test; }
+
+} // namespace init_list
+
+namespace base_ctor_call {
+
+void clang_analyzer_dump(int);
+
+struct foo {
+  int foox;
+  foo(int x) : foox(x) {}
+};
+
+class bar : public foo {
+public:
+  bar() : foo{42} {
+    clang_analyzer_dump(this->foox); // expected-warning{{42 S32b}}
+  }
+};
+
+void entry() { bar test; }
+
+} // namespace base_ctor_call
+
+namespace delegate_ctor_call {
+
+void clang_analyzer_dump(int);
+
+struct foo {
+  int foox;
+};
+
+struct bar : foo {
+  bar(int parx) { this->foox = parx; }
+  bar() : bar{42} {
+    clang_analyzer_dump(this->foox); // expected-warning{{42 S32b}}
+  }
+};
+
+void entry() { bar test; }
+
+} // namespace delegate_ctor_call

``````````

</details>


https://github.com/llvm/llvm-project/pull/70792