[llvm] [MC,ELF] Emit warning if a string constant contains newline char. (PR #98060)

[Sergei Barannikov via llvm-commits]

================
@@ -3125,6 +3125,16 @@ bool AsmParser::parseDirectiveAscii(StringRef IDVal, bool ZeroTerminated) {
     do {
       if (parseEscapedString(Data))
         return true;
+
+      // Warn about newline characters in parsed string like GAS.
+      size_t NewlinePos = -1;
+      size_t DataSize = Data.size();
+      const char *Start = getTok().getLoc().getPointer() - DataSize - 1;
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s-barannikov wrote:

The location will be incorrect if the string contains escaped characters (e.g. '\xFF'), and I don't see a way how you can reliably get the location of a newline without making `parseEscapedString` return it. Moreover, the string could contain '\n', which must not be diagnosed.


https://github.com/llvm/llvm-project/pull/98060