[flang] Implement a runtime routine to report fatal errors with source position

The title says it all.

I implemented a routine called "Crash" and added a test.

Differential Revision: https://reviews.llvm.org/D118509

Author: psteinfeld

flang/include/flang/Runtime/stop.h

@@ -30,6 +30,10 @@ NORETURN void RTNAME(ProgramEndStatement)(NO_ARGUMENTS);
 NORETURN void RTNAME(Exit)(int status = EXIT_SUCCESS);
 NORETURN void RTNAME(Abort)(NO_ARGUMENTS);
 
+// Crash with an error message when the program dynamically violates a Fortran
+// constraint.
+NORETURN void RTNAME(Crash)(const char *message, const char *source, int line);
+
 FORTRAN_EXTERN_C_END
 
 #endif // FORTRAN_RUNTIME_STOP_H_

flang/runtime/stop.cpp

@@ -143,4 +143,9 @@ void RTNAME(PauseStatementText)(const char *code, std::size_t length) {
 }
 
 [[noreturn]] void RTNAME(Abort)() { std::abort(); }
+
+[[noreturn]] void RTNAME(Crash)(
+    const char *message, const char *source, int line) {
+  Fortran::runtime::Terminator{source, line}.Crash(message);
+}
 }

flang/unittests/Runtime/Stop.cpp

@@ -83,3 +83,14 @@ TEST(TestProgramEnd, ExitTest) {
 }
 
 TEST(TestProgramEnd, AbortTest) { EXPECT_DEATH(RTNAME(Abort)(), ""); }
+
+TEST(TestProgramEnd, CrashTest) {
+  static const std::string crashMessage{"bad user code"};
+  static const std::string fileName{"file name"};
+  static const std::string headMessage{"fatal Fortran runtime error\\("};
+  static const std::string tailMessage{":343\\): "};
+  static const std::string fullMessage{
+      headMessage + fileName + tailMessage + crashMessage};
+  EXPECT_DEATH(RTNAME(Crash)(crashMessage.c_str(), fileName.c_str(), 343),
+      fullMessage.c_str());
+}