[analyzer] Delay the checker constructions after parsing (#127409)

If we were to delay checker constructions after we have a filled
ASTContext, then we could get rid of a bunch of "lazy initializers" in
checkers.

Turns out in the register functions of the checkers we could transfer
the ASTContext and all other things to checkers, so those could benefit
from in-class initializers and const fields.

For example, if a checker would take the ASTContext as the first field,
then the rest of the fields could use it in their in-class initializers,
so the ctor of the checker would only need to set a single field!

This would open uup countless opportunities for cleaning up the
asthetics of our checkers.

I attached a single use-case for the AST and the PP as demonstrating
purposes. You can imagine the rest.

**FYI: This may be a breaking change** to some downstream users that may
had some means to attach different listeners and what not to e.g. the
Preprocessor inside their checker register functions. Since we delay the
calls to these register fns after parsing is already done, they would of
course miss the parsing Preprocessor events.

Author: steakhal

clang/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp

@@ -40,17 +40,28 @@ enum class OpenVariant {
   OpenAt
 };
 
+static std::optional<int> getCreateFlagValue(const ASTContext &Ctx,
+                                             const Preprocessor &PP) {
+  std::optional<int> MacroVal = tryExpandAsInteger("O_CREAT", PP);
+  if (MacroVal.has_value())
+    return MacroVal;
+
+  // If we failed, fall-back to known values.
+  if (Ctx.getTargetInfo().getTriple().getVendor() == llvm::Triple::Apple)
+    return {0x0200};
+  return MacroVal;
+}
+
 namespace {
 
-class UnixAPIMisuseChecker
-    : public Checker<check::PreCall, check::ASTDecl<TranslationUnitDecl>> {
+class UnixAPIMisuseChecker : public Checker<check::PreCall> {
   const BugType BT_open{this, "Improper use of 'open'", categories::UnixAPI};
   const BugType BT_getline{this, "Improper use of getdelim",
                            categories::UnixAPI};
   const BugType BT_pthreadOnce{this, "Improper use of 'pthread_once'",
                                categories::UnixAPI};
   const BugType BT_ArgumentNull{this, "NULL pointer", categories::UnixAPI};
-  mutable std::optional<uint64_t> Val_O_CREAT;
+  const std::optional<int> Val_O_CREAT;
 
   ProgramStateRef
   EnsurePtrNotNull(SVal PtrVal, const Expr *PtrExpr, CheckerContext &C,
@@ -63,6 +74,9 @@ class UnixAPIMisuseChecker
       const Expr *SizePtrExpr, CheckerContext &C, ProgramStateRef State) const;
 
 public:
+  UnixAPIMisuseChecker(const ASTContext &Ctx, const Preprocessor &PP)
+      : Val_O_CREAT(getCreateFlagValue(Ctx, PP)) {}
+
   void checkASTDecl(const TranslationUnitDecl *TU, AnalysisManager &Mgr,
                     BugReporter &BR) const;
 
@@ -134,20 +148,6 @@ ProgramStateRef UnixAPIMisuseChecker::EnsurePtrNotNull(
   return PtrNotNull;
 }
 
-void UnixAPIMisuseChecker::checkASTDecl(const TranslationUnitDecl *TU,
-                                        AnalysisManager &Mgr,
-                                        BugReporter &) const {
-  // The definition of O_CREAT is platform specific.
-  // Try to get the macro value from the preprocessor.
-  Val_O_CREAT = tryExpandAsInteger("O_CREAT", Mgr.getPreprocessor());
-  // If we failed, fall-back to known values.
-  if (!Val_O_CREAT) {
-    if (TU->getASTContext().getTargetInfo().getTriple().getVendor() ==
-        llvm::Triple::Apple)
-      Val_O_CREAT = 0x0200;
-  }
-}
-
 //===----------------------------------------------------------------------===//
 // "open" (man 2 open)
 //===----------------------------------------------------------------------===/
@@ -262,7 +262,7 @@ void UnixAPIMisuseChecker::CheckOpenVariant(CheckerContext &C,
     return;
   }
 
-  if (!Val_O_CREAT) {
+  if (!Val_O_CREAT.has_value()) {
     return;
   }
 
@@ -276,7 +276,7 @@ void UnixAPIMisuseChecker::CheckOpenVariant(CheckerContext &C,
   }
   NonLoc oflags = V.castAs<NonLoc>();
   NonLoc ocreateFlag = C.getSValBuilder()
-                           .makeIntVal(*Val_O_CREAT, oflagsEx->getType())
+                           .makeIntVal(Val_O_CREAT.value(), oflagsEx->getType())
                            .castAs<NonLoc>();
   SVal maskedFlagsUC = C.getSValBuilder().evalBinOpNN(state, BO_And,
                                                       oflags, ocreateFlag,
@@ -621,14 +621,17 @@ void UnixAPIPortabilityChecker::checkPreStmt(const CallExpr *CE,
 // Registration.
 //===----------------------------------------------------------------------===//
 
-#define REGISTER_CHECKER(CHECKERNAME)                                          \
-  void ento::register##CHECKERNAME(CheckerManager &mgr) {                      \
-    mgr.registerChecker<CHECKERNAME>();                                        \
-  }                                                                            \
-                                                                               \
-  bool ento::shouldRegister##CHECKERNAME(const CheckerManager &mgr) {          \
-    return true;                                                               \
-  }
+void ento::registerUnixAPIMisuseChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<UnixAPIMisuseChecker>(Mgr.getASTContext(),
+                                            Mgr.getPreprocessor());
+}
+bool ento::shouldRegisterUnixAPIMisuseChecker(const CheckerManager &Mgr) {
+  return true;
+}
 
-REGISTER_CHECKER(UnixAPIMisuseChecker)
-REGISTER_CHECKER(UnixAPIPortabilityChecker)
+void ento::registerUnixAPIPortabilityChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<UnixAPIPortabilityChecker>();
+}
+bool ento::shouldRegisterUnixAPIPortabilityChecker(const CheckerManager &Mgr) {
+  return true;
+}

clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp

@@ -224,16 +224,6 @@ class AnalysisConsumer : public AnalysisASTConsumer,
     }
   }
 
-  void Initialize(ASTContext &Context) override {
-    Ctx = &Context;
-    checkerMgr = std::make_unique<CheckerManager>(*Ctx, Opts, PP, Plugins,
-                                                  CheckerRegistrationFns);
-
-    Mgr = std::make_unique<AnalysisManager>(*Ctx, PP, PathConsumers,
-                                            CreateStoreMgr, CreateConstraintMgr,
-                                            checkerMgr.get(), Opts, Injector);
-  }
-
   /// Store the top level decls in the set to be processed later on.
   /// (Doing this pre-processing avoids deserialization of data from PCH.)
   bool HandleTopLevelDecl(DeclGroupRef D) override;
@@ -615,6 +605,14 @@ void AnalysisConsumer::HandleTranslationUnit(ASTContext &C) {
   if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred())
     return;
 
+  Ctx = &C;
+  checkerMgr = std::make_unique<CheckerManager>(*Ctx, Opts, PP, Plugins,
+                                                CheckerRegistrationFns);
+
+  Mgr = std::make_unique<AnalysisManager>(*Ctx, PP, PathConsumers,
+                                          CreateStoreMgr, CreateConstraintMgr,
+                                          checkerMgr.get(), Opts, Injector);
+
   // Explicitly destroy the PathDiagnosticConsumer.  This will flush its output.
   // FIXME: This should be replaced with something that doesn't rely on
   // side-effects in PathDiagnosticConsumer's destructor. This is required when