[🍒] Merge commit '3f60d220514c' from llvm.org/main into next

clang/lib/Analysis/UnsafeBufferUsage.cpp

@@ -1650,11 +1650,27 @@ static bool hasAnyBoundsAttributes(const FunctionDecl *FD) {
          });
 }
 
+// Constant fold a conditional expression 'cond ? A : B' to
+// - 'A', if 'cond' has constant true value;
+// - 'B', if 'cond' has constant false value.
+static const Expr *tryConstantFoldConditionalExpr(const Expr *E,
+                                                  const ASTContext &Ctx) {
+  // FIXME: more places can use this function
+  if (const auto *CE = dyn_cast<ConditionalOperator>(E)) {
+    bool CondEval;
+
+    if (CE->getCond()->EvaluateAsBooleanCondition(CondEval, Ctx))
+      return CondEval ? CE->getLHS() : CE->getRHS();
+  }
+  return E;
+}
+
 // A pointer type expression is known to be null-terminated, if
 //  1. it is a string literal or `PredefinedExpr` (e.g., `__func__`);
 //  2. it has the form: E.c_str(), for any expression E of `std::string` type;
 //  3. it has `__null_terminated` type
 static bool isNullTermPointer(const Expr *Ptr, ASTContext &Ctx) {
+  Ptr = tryConstantFoldConditionalExpr(Ptr, Ctx);
   if (isa<clang::StringLiteral>(Ptr->IgnoreParenImpCasts()))
     return true;
   if (isa<PredefinedExpr>(Ptr->IgnoreParenImpCasts()))

clang/test/SemaCXX/warn-unsafe-buffer-usage-fold-conditional.cpp

@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -fsyntax-only -Wno-all -Wunsafe-buffer-usage -verify %s -std=c++20
+// RUN: %clang_cc1 -fsyntax-only -Wno-all -Wunsafe-buffer-usage -verify %s -x c
+// expected-no-diagnostics
+
+typedef struct {} FILE;
+int fprintf( FILE* stream, const char* format, ... );
+FILE * stderr;
+
+#define DEBUG_ASSERT_MESSAGE(name, assertion, label, message, file, line, value) \
+  fprintf(stderr, "AssertMacros: %s, %s file: %s, line: %d, value: %lld\n",      \
+          assertion, (message!=0) ? message : "", file, line, (long long) (value));
+
+
+#define Require(assertion, exceptionLabel)                              \
+  do                                                                    \
+    {                                                                   \
+      if ( __builtin_expect(!(assertion), 0) ) {                        \
+        DEBUG_ASSERT_MESSAGE(                                           \
+	  "DEBUG_ASSERT_COMPONENT_NAME_STRING",                         \
+	  #assertion, #exceptionLabel, 0, __FILE__, __LINE__,  0);      \
+	goto exceptionLabel;                                            \
+      }									\
+    } while ( 0 )
+
+
+void f(int x, int y) {
+  Require(x == y, L1);
+ L1:
+  return;
+}
+