[clang] [NFC][Static Analyzer] Rename and discuss about `NotNullConstraint` & `NotNullBufferConstraint` (PR #131374)

[Ziqing Luo via cfe-commits]

https://github.com/ziqingluo-90 created https://github.com/llvm/llvm-project/pull/131374

NotNullConstraint is used to check both null and non-null of a pointer.  So the name, which was created originally for just checking non-nullness, becomes less suitable.
The same reason applies to `NotNullBufferConstraint`.

Other than the names, I have some concerns noted in comments below. I'd like to discuss them with Static Analyzer folks!

>From fdc265eeca36dc877f56389d8dba39b5144447e6 Mon Sep 17 00:00:00 2001
From: Ziqing Luo <ziqing_luo at apple.com>
Date: Fri, 14 Mar 2025 11:13:46 -0700
Subject: [PATCH] [NFC][Static Analyzer] Rename `NotNullConstraint` &
 `NotNullBufferConstraint`

NotNullConstraint is used to check both null and non-null of a
pointer.  So the name, which was created originally for just checking
non-nullness, becomes less suitable.

The same reason applies to `NotNullBufferConstraint`.
---
 .../Checkers/StdLibraryFunctionsChecker.cpp   | 38 +++++++++----------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index fef19b4547555..3542b7c8aaf30 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -367,13 +367,13 @@ class StdLibraryFunctionsChecker
   };
 
   /// Check null or non-null-ness of an argument that is of pointer type.
-  class NotNullConstraint : public ValueConstraint {
+  class NullnessConstraint : public ValueConstraint {
     using ValueConstraint::ValueConstraint;
     // This variable has a role when we negate the constraint.
     bool CannotBeNull = true;
 
   public:
-    NotNullConstraint(ArgNo ArgN, bool CannotBeNull = true)
+    NullnessConstraint(ArgNo ArgN, bool CannotBeNull = true)
         : ValueConstraint(ArgN), CannotBeNull(CannotBeNull) {}
 
     ProgramStateRef apply(ProgramStateRef State, const CallEvent &Call,
@@ -389,9 +389,9 @@ class StdLibraryFunctionsChecker
                                llvm::raw_ostream &Out) const override;
 
     ValueConstraintPtr negate() const override {
-      NotNullConstraint Tmp(*this);
+      NullnessConstraint Tmp(*this);
       Tmp.CannotBeNull = !this->CannotBeNull;
-      return std::make_shared<NotNullConstraint>(Tmp);
+      return std::make_shared<NullnessConstraint>(Tmp);
     }
 
   protected:
@@ -407,9 +407,9 @@ class StdLibraryFunctionsChecker
   /// The argument is meant to be a buffer that has a size constraint, and it
   /// is allowed to have a NULL value if the size is 0. The size can depend on
   /// 1 or 2 additional arguments, if one of these is 0 the buffer is allowed to
-  /// be NULL. This is useful for functions like `fread` which have this special
-  /// property.
-  class NotNullBufferConstraint : public ValueConstraint {
+  /// be NULL. Otherwise, the buffer pointer must be non-null. This is useful
+  /// for functions like `fread` which have this special property.
+  class BufferNullnessConstraint : public ValueConstraint {
     using ValueConstraint::ValueConstraint;
     ArgNo SizeArg1N;
     std::optional<ArgNo> SizeArg2N;
@@ -417,7 +417,7 @@ class StdLibraryFunctionsChecker
     bool CannotBeNull = true;
 
   public:
-    NotNullBufferConstraint(ArgNo ArgN, ArgNo SizeArg1N,
+    BufferNullnessConstraint(ArgNo ArgN, ArgNo SizeArg1N,
                             std::optional<ArgNo> SizeArg2N,
                             bool CannotBeNull = true)
         : ValueConstraint(ArgN), SizeArg1N(SizeArg1N), SizeArg2N(SizeArg2N),
@@ -436,9 +436,9 @@ class StdLibraryFunctionsChecker
                                llvm::raw_ostream &Out) const override;
 
     ValueConstraintPtr negate() const override {
-      NotNullBufferConstraint Tmp(*this);
+      BufferNullnessConstraint Tmp(*this);
       Tmp.CannotBeNull = !this->CannotBeNull;
-      return std::make_shared<NotNullBufferConstraint>(Tmp);
+      return std::make_shared<BufferNullnessConstraint>(Tmp);
     }
 
   protected:
@@ -1151,7 +1151,7 @@ ProgramStateRef StdLibraryFunctionsChecker::ComparisonConstraint::apply(
   return State;
 }
 
-ProgramStateRef StdLibraryFunctionsChecker::NotNullConstraint::apply(
+ProgramStateRef StdLibraryFunctionsChecker::NullnessConstraint::apply(
     ProgramStateRef State, const CallEvent &Call, const Summary &Summary,
     CheckerContext &C) const {
   SVal V = getArgSVal(Call, getArgNo());
@@ -1165,7 +1165,7 @@ ProgramStateRef StdLibraryFunctionsChecker::NotNullConstraint::apply(
   return State->assume(L, CannotBeNull);
 }
 
-void StdLibraryFunctionsChecker::NotNullConstraint::describe(
+void StdLibraryFunctionsChecker::NullnessConstraint::describe(
     DescriptionKind DK, const CallEvent &Call, ProgramStateRef State,
     const Summary &Summary, llvm::raw_ostream &Out) const {
   assert(CannotBeNull &&
@@ -1176,7 +1176,7 @@ void StdLibraryFunctionsChecker::NotNullConstraint::describe(
     Out << "is not NULL";
 }
 
-bool StdLibraryFunctionsChecker::NotNullConstraint::describeArgumentValue(
+bool StdLibraryFunctionsChecker::NullnessConstraint::describeArgumentValue(
     const CallEvent &Call, ProgramStateRef State, const Summary &Summary,
     llvm::raw_ostream &Out) const {
   assert(!CannotBeNull && "This function is used when the value is NULL");
@@ -1184,7 +1184,7 @@ bool StdLibraryFunctionsChecker::NotNullConstraint::describeArgumentValue(
   return true;
 }
 
-ProgramStateRef StdLibraryFunctionsChecker::NotNullBufferConstraint::apply(
+ProgramStateRef StdLibraryFunctionsChecker::BufferNullnessConstraint::apply(
     ProgramStateRef State, const CallEvent &Call, const Summary &Summary,
     CheckerContext &C) const {
   SVal V = getArgSVal(Call, getArgNo());
@@ -1213,7 +1213,7 @@ ProgramStateRef StdLibraryFunctionsChecker::NotNullBufferConstraint::apply(
   return State->assume(L, CannotBeNull);
 }
 
-void StdLibraryFunctionsChecker::NotNullBufferConstraint::describe(
+void StdLibraryFunctionsChecker::BufferNullnessConstraint::describe(
     DescriptionKind DK, const CallEvent &Call, ProgramStateRef State,
     const Summary &Summary, llvm::raw_ostream &Out) const {
   assert(CannotBeNull &&
@@ -1224,7 +1224,7 @@ void StdLibraryFunctionsChecker::NotNullBufferConstraint::describe(
     Out << "is not NULL";
 }
 
-bool StdLibraryFunctionsChecker::NotNullBufferConstraint::describeArgumentValue(
+bool StdLibraryFunctionsChecker::BufferNullnessConstraint::describeArgumentValue(
     const CallEvent &Call, ProgramStateRef State, const Summary &Summary,
     llvm::raw_ostream &Out) const {
   assert(!CannotBeNull && "This function is used when the value is NULL");
@@ -1792,14 +1792,14 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
   };
   auto LessThanOrEq = BO_LE;
   auto NotNull = [&](ArgNo ArgN) {
-    return std::make_shared<NotNullConstraint>(ArgN);
+    return std::make_shared<NullnessConstraint>(ArgN);
   };
   auto IsNull = [&](ArgNo ArgN) {
-    return std::make_shared<NotNullConstraint>(ArgN, false);
+    return std::make_shared<NullnessConstraint>(ArgN, false);
   };
   auto NotNullBuffer = [&](ArgNo ArgN, ArgNo SizeArg1N,
                            std::optional<ArgNo> SizeArg2N = std::nullopt) {
-    return std::make_shared<NotNullBufferConstraint>(ArgN, SizeArg1N,
+    return std::make_shared<BufferNullnessConstraint>(ArgN, SizeArg1N,
                                                      SizeArg2N);
   };