[clang] [clang][dataflow] Check for backedges directly (instead of loop statements). (PR #68923)

[via cfe-commits]

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@@ -913,6 +913,34 @@ TEST_F(FlowConditionTest, WhileStmt) {
       });
 }
 
+TEST_F(FlowConditionTest, WhileStmtWithAssignmentInCondition) {
+  std::string Code = R"(
+    void target(bool Foo) {
+      // This test checks whether the analysis preserves the connection between
+      // the value of `Foo` and the assignment expression, despite widening.
+      // The equality operator generates a fresh boolean variable on each
+      // interpretation, which forces use of widening.
+      while ((Foo = (3 == 4))) {
+        (void)0;
+        /*[[p]]*/
+      }
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+        ASSERT_THAT(FooDecl, NotNull());
+
+        ASSERT_THAT(Results.keys(), UnorderedElementsAre("p"));
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martinboehme wrote:

Suggest deleting this assertion. `getEnvironmentAtAnnotation()` already asserts that an annotation "p" exists.

(I know we assert this in a lot of existing tests, but it just seems like clutter.)

https://github.com/llvm/llvm-project/pull/68923