[clang] [Clang][UnsafeBufferUsage] Warn about two-arg string_view constructors. (PR #180471)

[Rohan Jacob-Rao via cfe-commits]

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@@ -699,6 +699,45 @@ static bool isSafeSpanTwoParamConstruct(const CXXConstructExpr &Node,
   return isPtrBufferSafe(Arg0, Arg1, Ctx);
 }
 
+static bool isSafeStringViewTwoParamConstruct(const CXXConstructExpr &Node,
+                                              ASTContext &Ctx) {
+  const Expr *Arg0 = Node.getArg(0)->IgnoreParenImpCasts();
+  const Expr *Arg1 = Node.getArg(1)->IgnoreParenImpCasts();
+
+  // Pattern 1: String Literals (Safe if size <= length)
+  if (const auto *SL = dyn_cast<StringLiteral>(Arg0)) {
+    if (auto ArgSize = Arg1->getIntegerConstantExpr(Ctx)) {
+      if (ArgSize->getZExtValue() <= SL->getLength())
+        return true;
+    }
+  }
+
+  // Pattern 2: Constant Arrays (Safe if exact match)
+  QualType T0 = Arg0->getType().getCanonicalType();
+  if (const auto *CAT = Ctx.getAsConstantArrayType(T0)) {
+   if (auto ArgSize = Arg1->getIntegerConstantExpr(Ctx)) {
+     // Wrap CAT->getSize() in APSInt to match ArgSize's type
+     if (llvm::APSInt::compareValues(llvm::APSInt(CAT->getSize(), /*isUnsigned=*/true), 
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rohanjr wrote:

Is it also safe if the size argument is less than the array size?

https://github.com/llvm/llvm-project/pull/180471