[clang] [alpha.webkit.ForwardDeclChecker] Ignore forward declared struct. (PR #133804)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Ryosuke Niwa (rniwa)

<details>
<summary>Changes</summary>

There are some system libraries such as sqlite3 which forward declare a struct then use a pointer to that forward declared type in various APIs. Ignore these types ForwardDeclChecker like other pointer types.

---
Full diff: https://github.com/llvm/llvm-project/pull/133804.diff


2 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Checkers/WebKit/ForwardDeclChecker.cpp (+5-5) 
- (modified) clang/test/Analysis/Checkers/WebKit/forward-decl-checker.mm (+4) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/ForwardDeclChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/ForwardDeclChecker.cpp
index a524593b0119b..399ae9e0a6874 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/ForwardDeclChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/ForwardDeclChecker.cpp
@@ -108,17 +108,16 @@ class ForwardDeclChecker : public Checker<check::ASTDecl<TranslationUnitDecl>> {
     RTC.visitTypedef(TD);
     auto QT = TD->getUnderlyingType().getCanonicalType();
     if (BR->getSourceManager().isInSystemHeader(TD->getBeginLoc())) {
-      if (auto *Type = QT.getTypePtrOrNull(); Type && QT->isPointerType())
+      if (auto *Type = QT.getTypePtrOrNull())
         SystemTypes.insert(Type);
     }
   }
 
   bool isUnknownType(QualType QT) const {
-    auto *Type = QT.getTypePtrOrNull();
-    if (!Type)
-      return false;
     auto *CanonicalType = QT.getCanonicalType().getTypePtrOrNull();
-    auto PointeeQT = Type->getPointeeType();
+    if (!CanonicalType)
+      return false;
+    auto PointeeQT = CanonicalType->getPointeeType();
     auto *PointeeType = PointeeQT.getTypePtrOrNull();
     if (!PointeeType)
       return false;
@@ -128,6 +127,7 @@ class ForwardDeclChecker : public Checker<check::ASTDecl<TranslationUnitDecl>> {
     auto Name = R->getName();
     return !R->hasDefinition() && !RTC.isUnretained(QT) &&
            !SystemTypes.contains(CanonicalType) &&
+           !SystemTypes.contains(PointeeType) &&
            !Name.starts_with("Opaque") && Name != "_NSZone";
   }
 
diff --git a/clang/test/Analysis/Checkers/WebKit/forward-decl-checker.mm b/clang/test/Analysis/Checkers/WebKit/forward-decl-checker.mm
index 151cbe2affa92..64100d60c4867 100644
--- a/clang/test/Analysis/Checkers/WebKit/forward-decl-checker.mm
+++ b/clang/test/Analysis/Checkers/WebKit/forward-decl-checker.mm
@@ -25,6 +25,8 @@
 
 Obj* provide_obj_ptr();
 void receive_obj_ptr(Obj* p = nullptr);
+sqlite3* open_db();
+void close_db(sqlite3*);
 
 Obj* ptr(Obj* arg) {
   receive_obj_ptr(provide_obj_ptr());
@@ -34,6 +36,8 @@
   receive_obj_ptr(arg);
   receive_obj_ptr(nullptr);
   receive_obj_ptr();
+  auto* db = open_db();
+  close_db(db);
   return obj;
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/133804