[clang] [clang-tools-extra] [lldb] [llvm] [mlir] [Support] Validate number of arguments passed to formatv() (PR #105745)

[Rahul Joshi via cfe-commits]

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@@ -74,16 +75,31 @@ class formatv_object_base {
   static std::pair<ReplacementItem, StringRef>
   splitLiteralAndReplacement(StringRef Fmt);
 
-  formatv_object_base(StringRef Fmt,
+  formatv_object_base(StringRef Fmt, bool ValidateNumArgs,
                       ArrayRef<support::detail::format_adapter *> Adapters)
-      : Fmt(Fmt), Adapters(Adapters) {}
+      : Fmt(Fmt), ValidateNumArgs(ValidateNumArgs), Adapters(Adapters) {}
 
   formatv_object_base(formatv_object_base const &rhs) = delete;
   formatv_object_base(formatv_object_base &&rhs) = default;
 
 public:
   void format(raw_ostream &S) const {
-    for (auto &R : parseFormatString(Fmt)) {
+    const auto [Replacements, NumExpectedParams] = parseFormatString(Fmt);
+    // Fail formatv() call if the number of replacement parameters provided
+    // does not match the expected number after parsing the format string.
+    // Assert in debug builds.
+    if (ValidateNumArgs && NumExpectedParams != Adapters.size()) {
+      errs() << "Invalid format() in formatv: " << Fmt << "\n";
+      assert(0 &&
+             "Mismatch between replacement parameters expected and provided");
+
+      S << "formatv() error: " << NumExpectedParams
+        << " replacement parameters expected, but " << Adapters.size()
+        << " provided";
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jurahul wrote:

Thanks. This is not ready for review yet. I wanted to run CI locally as I suspect I need to fix more issues before it runs clean. But yes, we can tweak what gets dumped into the stream in error case for release builds.

https://github.com/llvm/llvm-project/pull/105745