[clang] [alpha.webkit.UncountedLocalVarsChecker] Ignore a VarDecl in "if" with trivial "then" (PR #171764)

[Balázs Benics via cfe-commits]

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@@ -492,4 +492,42 @@ namespace virtual_function {
     auto* baz = &*obj;
     // expected-warning at -1{{Local variable 'baz' is uncounted and unsafe [alpha.webkit.UncountedLocalVarsChecker]}}
   }
-}
\ No newline at end of file
+}
+
+namespace vardecl_in_if_condition {
+  RefCountable* provide();
+
+  RefCountable* get() {
+    if (auto* obj = provide())
+      return obj; // no warning
+    return nullptr;
+  }
+
+  RefCountable* get_non_trivial_then() {
+    if (auto* obj = provide()) // expected-warning{{Local variable 'obj' is uncounted and unsafe [alpha.webkit.UncountedLocalVarsChecker]}}
+      return obj->next();
+    return nullptr;
+  }
+
+  RefCountable* get_non_trivial_else() {
+    if (auto* obj = provide())
+      return obj;
+    else
+      return provide()->next();
+    return nullptr;
+  }
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steakhal wrote:

ah nvm, you already added one. Great. it actually shows that the suppression logic does not apply there. but at least it does no harm so we should be on the safe side.

https://github.com/llvm/llvm-project/pull/171764