[Windows] Add test coverage for line endings when rewriting includes

[aganea]

Summary

Validate that we properly generating a single line ending on Windows when using -frewrite-includes. Otherwise we're breaking split-line macros. The test fails before D99837.

See discussion in https://reviews.llvm.org/D96363#2650460 and D99426

[mstorsjo]

Not very familiar with the feature, but from the linked discussion it looks sensible to me, so +1, I can give a formal stamp a bit later if nobody else does.

clang/test/Frontend/rewrite-includes-macros.cpp

15

I guess the missing newline at end of file isn't one of the aspects that needs to be tested?

[abhina.sreeskantharajan]

LGTM, thanks for adding a testcase!

[aganea]

clang/test/Frontend/rewrite-includes-macros.cpp

15

It is not indeed, I'll fix that, thanks!

clang/test/Frontend/rewrite-includes-macros.cpp

+// REQUIRES: system-windows
+// RUN: %clang_cl /E -Xclang -frewrite-includes %s | %clang_cl /c -Xclang -verify /Tp -
+// expected-no-diagnostics
+
+int foo();
+int bar();
+#define HELLO \
+  foo(); \
+  bar();
+
+int main() {
+  HELLO
+  return 0;
+}