[scudo] Change overloaded function name append.

[cferris]

Summary

The ScopedString class has two functions named append. One takes
a va_list, but on some platforms va_list is typedef'd to char*.
That means that this call:

std::string value;
Str.append("print this string %s", value.c_str());

The compiler can incorrectly think this is the va_list function,
leading to crashes when calling this. To fix this, change the name
of the va_list function to be vappend to avoid this.

Fix https://github.com/llvm/llvm-project/issues/62893

[cferris]

Missed a couple of calls that should be vappend.

compiler-rt/lib/scudo/standalone/report.cpp

 namespace scudo {
 
 class ScopedErrorReport {
 public:
   ScopedErrorReport() : Message() { Message.append("Scudo ERROR: "); }
   void append(const char *Format, ...) {
     va_list Args;
     va_start(Args, Format);
-    Message.append(Format, Args);
+    Message.vappend(Format, Args);
     va_end(Args);
   }
   NORETURN ~ScopedErrorReport() {
     outputRaw(Message.data());
     setAbortMessage(Message.data());
     die();
   }
 

compiler-rt/lib/scudo/standalone/string_utils.h

 public:
   explicit ScopedString() { String.push_back('\0'); }
   uptr length() { return String.size() - 1; }
   const char *data() { return String.data(); }
   void clear() {
     String.clear();
     String.push_back('\0');
   }
-  void append(const char *Format, va_list Args);
+  void vappend(const char *Format, va_list Args);
   void append(const char *Format, ...) FORMAT(2, 3);
   void output() const { outputRaw(String.data()); }
   void reserve(size_t Size) { String.reserve(Size + 1); }
 
 private:
   Vector<char> String;
 };
 
 int formatString(char *Buffer, uptr BufferLength, const char *Format, ...)
     FORMAT(3, 4);
 void Printf(const char *Format, ...) FORMAT(1, 2);
 
 } // namespace scudo
 
 #endif // SCUDO_STRING_UTILS_H_

compiler-rt/lib/scudo/standalone/string_utils.cpp

 int formatString(char *Buffer, uptr BufferLength, const char *Format, ...) {
   va_list Args;
   va_start(Args, Format);
   int Res = formatString(Buffer, BufferLength, Format, Args);
   va_end(Args);
   return Res;
 }
 
-void ScopedString::append(const char *Format, va_list Args) {
+void ScopedString::vappend(const char *Format, va_list Args) {
   va_list ArgsCopy;
   va_copy(ArgsCopy, Args);
   // formatString doesn't currently support a null buffer or zero buffer length,
   // so in order to get the resulting formatted string length, we use a one-char
   // buffer.
   char C[1];
   const uptr AdditionalLength =
       static_cast<uptr>(formatString(C, sizeof(C), Format, Args)) + 1;
   const uptr Length = length();
   String.resize(Length + AdditionalLength);
   const uptr FormattedLength = static_cast<uptr>(formatString(
       String.data() + Length, String.size() - Length, Format, ArgsCopy));
   RAW_CHECK(data()[length()] == '\0');
   RAW_CHECK(FormattedLength + 1 == AdditionalLength);
   va_end(ArgsCopy);
 }
 
 void ScopedString::append(const char *Format, ...) {
   va_list Args;
   va_start(Args, Format);
-  append(Format, Args);
+  vappend(Format, Args);
   va_end(Args);
 }
 
 void Printf(const char *Format, ...) {
   va_list Args;
   va_start(Args, Format);
   ScopedString Msg;
-  Msg.append(Format, Args);
+  Msg.vappend(Format, Args);
   outputRaw(Msg.data());
   va_end(Args);
 }
 
 } // namespace scudo