[AutoBump] Merge with 894d3eeb (Aug 15) (4)

.git-blame-ignore-revs

@@ -93,3 +93,4 @@ b32931c5b32eb0d2cf37d688b34f8548c9674c19
 b6262880b34629e9d7a72b5a42f315a3c9ed8139
 39c7dc7207e76e72da21cf4fedda21b5311bf62d
 e80bc777749331e9519575f416c342f7626dd14d
+7e5cd8f1b6c5263ed5e2cc03d60c8779a8d3e9f7

clang-tools-extra/include-cleaner/lib/WalkAST.cpp

@@ -271,15 +271,13 @@ class ASTWalker : public RecursiveASTVisitor<ASTWalker> {
   // specialized template. Implicit ones are filtered out by RAV.
   bool
   VisitClassTemplateSpecializationDecl(ClassTemplateSpecializationDecl *CTSD) {
-    // if (CTSD->isExplicitSpecialization())
     if (clang::isTemplateExplicitInstantiationOrSpecialization(
             CTSD->getTemplateSpecializationKind()))
       report(CTSD->getLocation(),
              CTSD->getSpecializedTemplate()->getTemplatedDecl());
     return true;
   }
   bool VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *VTSD) {
-    // if (VTSD->isExplicitSpecialization())
     if (clang::isTemplateExplicitInstantiationOrSpecialization(
             VTSD->getTemplateSpecializationKind()))
       report(VTSD->getLocation(),

clang/docs/LanguageExtensions.rst

@@ -1547,6 +1547,7 @@ The following type trait primitives are supported by Clang. Those traits marked
 * ``__array_extent(type, dim)`` (Embarcadero):
   The ``dim``'th array bound in the type ``type``, or ``0`` if
   ``dim >= __array_rank(type)``.
+* ``__builtin_is_implicit_lifetime`` (C++, GNU, Microsoft)
 * ``__builtin_is_virtual_base_of`` (C++, GNU, Microsoft)
 * ``__can_pass_in_regs`` (C++)
   Returns whether a class can be passed in registers under the current

clang/docs/ReleaseNotes.rst

@@ -49,9 +49,36 @@ C++ Specific Potentially Breaking Changes
   few users and can be written as ``__is_same(__remove_cv(T), decltype(nullptr))``,
   which GCC supports as well.
 
+- Clang will now correctly diagnose as ill-formed a constant expression where an
+  enum without a fixed underlying type is set to a value outside the range of
+  the enumeration's values.
+
+  .. code-block:: c++
+
+    enum E { Zero, One, Two, Three, Four };
+    constexpr E Val1 = (E)3;  // Ok
+    constexpr E Val2 = (E)7;  // Ok
+    constexpr E Val3 = (E)8;  // Now ill-formed, out of the range [0, 7]
+    constexpr E Val4 = (E)-1; // Now ill-formed, out of the range [0, 7]
+
+  Since Clang 16, it has been possible to suppress the diagnostic via
+  `-Wno-enum-constexpr-conversion`, to allow for a transition period for users.
+  Now, in Clang 20, **it is no longer possible to suppress the diagnostic**.
+
+- Extraneous template headers are now ill-formed by default.
+  This error can be disable with ``-Wno-error=extraneous-template-head``.
+
+  .. code-block:: c++
+
+    template <> // error: extraneous template head
+    template <typename T>
+    void f();
+
 ABI Changes in This Version
 ---------------------------
 
+- Fixed Microsoft name mangling of placeholder, auto and decltype(auto), return types for MSVC 1920+. This change resolves incompatibilities with code compiled by MSVC 1920+ but will introduce incompatibilities with code compiled by earlier versions of Clang unless such code is built with the compiler option -fms-compatibility-version=19.14 to imitate the MSVC 1914 mangling behavior.
+
 AST Dumping Potentially Breaking Changes
 ----------------------------------------
 
@@ -95,6 +122,9 @@ C++23 Feature Support
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
+- Add ``__builtin_is_implicit_lifetime`` intrinsic, which supports
+  `P2647R1 A trait for implicit lifetime types <https://wg21.link/p2674r1>`_
+
 - Add ``__builtin_is_virtual_base_of`` intrinsic, which supports
   `P2985R0 A type trait for detecting virtual base classes <https://wg21.link/p2985r0>`_
 
@@ -140,6 +170,11 @@ Modified Compiler Flags
 Removed Compiler Flags
 -------------------------
 
+- The compiler flag `-Wenum-constexpr-conversion` (and the `Wno-`, `Wno-error-`
+  derivatives) is now removed, since it's no longer possible to suppress the
+  diagnostic (see above). Users can expect an `unknown warning` diagnostic if
+  it's still in use.
+
 Attribute Changes in Clang
 --------------------------
 
@@ -217,8 +252,10 @@ Bug Fixes to C++ Support
 - Clang now preserves the unexpanded flag in a lambda transform used for pack expansion. (#GH56852), (#GH85667),
   (#GH99877).
 - Fixed a bug when diagnosing ambiguous explicit specializations of constrained member functions.
-- Fixed an assertion failure when selecting a function from an overload set that includes a 
+- Fixed an assertion failure when selecting a function from an overload set that includes a
   specialization of a conversion function template.
+- Correctly diagnose attempts to use a concept name in its own definition;
+  A concept name is introduced to its scope sooner to match the C++ standard. (#GH55875)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -347,11 +384,46 @@ Improvements
 Moved checkers
 ^^^^^^^^^^^^^^
 
+- The checker ``alpha.security.MallocOverflow`` was deleted because it was
+  badly implemented and its agressive logic produced too many false positives.
+  To detect too large arguments passed to malloc, consider using the checker
+  ``alpha.taint.TaintedAlloc``.
+
 .. _release-notes-sanitizers:
 
 Sanitizers
 ----------
 
+- Added the ``-fsanitize-overflow-pattern-exclusion=`` flag which can be used
+  to disable specific overflow-dependent code patterns. The supported patterns
+  are: ``add-overflow-test``, ``negated-unsigned-const``, and
+  ``post-decr-while``. The sanitizer instrumentation can be toggled off for all
+  available patterns by specifying ``all``. Conversely, you can disable all
+  exclusions with ``none``.
+
+  .. code-block:: c++
+
+     /// specified with ``-fsanitize-overflow-pattern-exclusion=add-overflow-test``
+     int common_overflow_check_pattern(unsigned base, unsigned offset) {
+       if (base + offset < base) { /* ... */ } // The pattern of `a + b < a`, and other re-orderings, won't be instrumented
+     }
+
+     /// specified with ``-fsanitize-overflow-pattern-exclusion=negated-unsigned-const``
+     void negation_overflow() {
+       unsigned long foo = -1UL; // No longer causes a negation overflow warning
+       unsigned long bar = -2UL; // and so on...
+     }
+
+     /// specified with ``-fsanitize-overflow-pattern-exclusion=post-decr-while``
+     void while_post_decrement() {
+       unsigned char count = 16;
+       while (count--) { /* ... */} // No longer causes unsigned-integer-overflow sanitizer to trip
+     }
+
+  Many existing projects have a large amount of these code patterns present.
+  This new flag should allow those projects to enable integer sanitizers with
+  less noise.
+
 Python Binding Changes
 ----------------------
 - Fixed an issue that led to crashes when calling ``Type.get_exception_specification_kind``.

clang/docs/UndefinedBehaviorSanitizer.rst

@@ -293,6 +293,48 @@ To silence reports from unsigned integer overflow, you can set
 ``-fsanitize-recover=unsigned-integer-overflow``, is particularly useful for
 providing fuzzing signal without blowing up logs.
 
+Disabling instrumentation for common overflow patterns
+------------------------------------------------------
+
+There are certain overflow-dependent or overflow-prone code patterns which
+produce a lot of noise for integer overflow/truncation sanitizers. Negated
+unsigned constants, post-decrements in a while loop condition and simple
+overflow checks are accepted and pervasive code patterns. However, the signal
+received from sanitizers instrumenting these code patterns may be too noisy for
+some projects. To disable instrumentation for these common patterns one should
+use ``-fsanitize-overflow-pattern-exclusion=``.
+
+Currently, this option supports three overflow-dependent code idioms:
+
+``negated-unsigned-const``
+
+.. code-block:: c++
+
+    /// -fsanitize-overflow-pattern-exclusion=negated-unsigned-const
+    unsigned long foo = -1UL; // No longer causes a negation overflow warning
+    unsigned long bar = -2UL; // and so on...
+
+``post-decr-while``
+
+.. code-block:: c++
+
+    /// -fsanitize-overflow-pattern-exclusion=post-decr-while
+    unsigned char count = 16;
+    while (count--) { /* ... */ } // No longer causes unsigned-integer-overflow sanitizer to trip
+
+``add-overflow-test``
+
+.. code-block:: c++
+
+    /// -fsanitize-overflow-pattern-exclusion=add-overflow-test
+    if (base + offset < base) { /* ... */ } // The pattern of `a + b < a`, and other re-orderings,
+                                            // won't be instrumented (same for signed types)
+
+You can enable all exclusions with
+``-fsanitize-overflow-pattern-exclusion=all`` or disable all exclusions with
+``-fsanitize-overflow-pattern-exclusion=none``. Specifying ``none`` has
+precedence over other values.
+
 Issue Suppression
 =================
 

clang/docs/analyzer/checkers.rst

@@ -2951,49 +2951,6 @@ Warn about buffer overflows (newer checker).
    char c = s[x]; // warn: index is tainted
  }
 
-.. _alpha-security-MallocOverflow:
-
-alpha.security.MallocOverflow (C)
-"""""""""""""""""""""""""""""""""
-Check for overflows in the arguments to ``malloc()``.
-It tries to catch ``malloc(n * c)`` patterns, where:
-
- - ``n``: a variable or member access of an object
- - ``c``: a constant foldable integral
-
-This checker was designed for code audits, so expect false-positive reports.
-One is supposed to silence this checker by ensuring proper bounds checking on
-the variable in question using e.g. an ``assert()`` or a branch.
-
-.. code-block:: c
-
- void test(int n) {
-   void *p = malloc(n * sizeof(int)); // warn
- }
-
- void test2(int n) {
-   if (n > 100) // gives an upper-bound
-     return;
-   void *p = malloc(n * sizeof(int)); // no warning
- }
-
- void test3(int n) {
-   assert(n <= 100 && "Contract violated.");
-   void *p = malloc(n * sizeof(int)); // no warning
- }
-
-Limitations:
-
- - The checker won't warn for variables involved in explicit casts,
-   since that might limit the variable's domain.
-   E.g.: ``(unsigned char)int x`` would limit the domain to ``[0,255]``.
-   The checker will miss the true-positive cases when the explicit cast would
-   not tighten the domain to prevent the overflow in the subsequent
-   multiplication operation.
-
- - It is an AST-based checker, thus it does not make use of the
-   path-sensitive taint-analysis.
-
 .. _alpha-security-MmapWriteExec:
 
 alpha.security.MmapWriteExec (C)

clang/include/clang/AST/Decl.h

@@ -3206,6 +3206,10 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
   /// Set the C++11 in-class initializer for this member.
   void setInClassInitializer(Expr *NewInit);
 
+  /// Find the FieldDecl specified in a FAM's "counted_by" attribute. Returns
+  /// \p nullptr if either the attribute or the field doesn't exist.
+  const FieldDecl *findCountedByField() const;
+
 private:
   void setLazyInClassInitializer(LazyDeclStmtPtr NewInit);
 

clang/include/clang/AST/DeclTemplate.h

@@ -3146,19 +3146,24 @@ class ConceptDecl : public TemplateDecl, public Mergeable<ConceptDecl> {
       : TemplateDecl(Concept, DC, L, Name, Params),
         ConstraintExpr(ConstraintExpr) {};
 public:
-  static ConceptDecl *Create(ASTContext &C, DeclContext *DC,
-                             SourceLocation L, DeclarationName Name,
+  static ConceptDecl *Create(ASTContext &C, DeclContext *DC, SourceLocation L,
+                             DeclarationName Name,
                              TemplateParameterList *Params,
-                             Expr *ConstraintExpr);
+                             Expr *ConstraintExpr = nullptr);
   static ConceptDecl *CreateDeserialized(ASTContext &C, GlobalDeclID ID);
 
   Expr *getConstraintExpr() const {
     return ConstraintExpr;
   }
 
+  bool hasDefinition() const { return ConstraintExpr != nullptr; }
+
+  void setDefinition(Expr *E) { ConstraintExpr = E; }
+
   SourceRange getSourceRange() const override LLVM_READONLY {
     return SourceRange(getTemplateParameters()->getTemplateLoc(),
-                       ConstraintExpr->getEndLoc());
+                       ConstraintExpr ? ConstraintExpr->getEndLoc()
+                                      : SourceLocation());
   }
 
   bool isTypeConcept() const {

clang/include/clang/AST/Expr.h

@@ -4043,6 +4043,15 @@ class BinaryOperator : public Expr {
   void setHasStoredFPFeatures(bool B) { BinaryOperatorBits.HasFPFeatures = B; }
   bool hasStoredFPFeatures() const { return BinaryOperatorBits.HasFPFeatures; }
 
+  /// Set and get the bit that informs arithmetic overflow sanitizers whether
+  /// or not they should exclude certain BinaryOperators from instrumentation
+  void setExcludedOverflowPattern(bool B) {
+    BinaryOperatorBits.ExcludedOverflowPattern = B;
+  }
+  bool hasExcludedOverflowPattern() const {
+    return BinaryOperatorBits.ExcludedOverflowPattern;
+  }
+
   /// Get FPFeatures from trailing storage
   FPOptionsOverride getStoredFPFeatures() const {
     assert(hasStoredFPFeatures());

clang/include/clang/AST/Stmt.h

@@ -650,6 +650,11 @@ class alignas(void *) Stmt {
     LLVM_PREFERRED_TYPE(bool)
     unsigned HasFPFeatures : 1;
 
+    /// Whether or not this BinaryOperator should be excluded from integer
+    /// overflow sanitization.
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned ExcludedOverflowPattern : 1;
+
     SourceLocation OpLoc;
   };
 

clang/include/clang/Basic/Attr.td

@@ -4467,7 +4467,7 @@ def ReleaseHandle : InheritableParamAttr {
 
 def UnsafeBufferUsage : InheritableAttr {
   let Spellings = [Clang<"unsafe_buffer_usage">];
-  let Subjects = SubjectList<[Function]>;
+  let Subjects = SubjectList<[Function, Field]>;
   let Documentation = [UnsafeBufferUsageDocs];
 }
 
@@ -4599,12 +4599,18 @@ def HLSLResource : InheritableAttr {
           "CBuffer", "Sampler", "TBuffer", "RTAccelerationStructure",
           "FeedbackTexture2D", "FeedbackTexture2DArray"
         ],
-        /*opt=*/0, /*fake=*/0, /*isExternalType=*/1, /*isCovered=*/0>,
-    DefaultBoolArgument<"isROV", /*default=*/0>
+        /*opt=*/0, /*fake=*/0, /*isExternalType=*/1, /*isCovered=*/0>
   ];
   let Documentation = [InternalOnly];
 }
 
+def HLSLROV : InheritableAttr {
+  let Spellings = [CXX11<"hlsl", "is_rov">];
+  let Subjects = SubjectList<[Struct]>;
+  let LangOpts = [HLSL]; 
+  let Documentation = [InternalOnly];
+}
+
 def HLSLResourceClass : InheritableAttr {
   let Spellings = [CXX11<"hlsl", "resource_class">];
   let Subjects = SubjectList<[Struct]>;