[clang-repl] Fix dynamic library test to avoid cstdio and linker

[argentite]

Summary

Some platforms do not have a working linker present. The goal is to
only test the loading of a shared library in clang-repl. A precompiled
library is used instead.

The cstdio header may also not be present. We only need printf.

Related discussion in D141824

[zhuhan0]

LGTM. Thanks!

[sgraenitz]

clang/test/Interpreter/dynamic-library.cpp

11

Should we wrap this in a extern "C" block? Otherwise, the shared library has a C++ interface, which is not stable. It won't matter in this simple case, but the test might become a pattern.

[argentite]

extern "C" and enable PS4/5

[sgraenitz]

Thanks. LGTM

clang/test/Interpreter/Inputs/dynamic-library-test.cpp

-int ultimate_answer = 0;
-
-int calculate_answer() {
-  ultimate_answer = 42;
-  return 5;
-}

clang/test/Interpreter/dynamic-library.cpp

 // REQUIRES: host-supports-jit, system-linux
-// UNSUPPORTED: target={{.*-(ps4|ps5)}}
 
-// RUN: %clang -xc++ -o %T/libdynamic-library-test.so -fPIC -shared -DLIBRARY %S/Inputs/dynamic-library-test.cpp
-// RUN: cat %s | env LD_LIBRARY_PATH=%T:$LD_LIBRARY_PATH clang-repl | FileCheck %s
+// To generate libdynamic-library-test.so :
+// clang -xc++ -o libdynamic-library-test.so -fPIC -shared
+//
+// extern "C" {
+//
+// int ultimate_answer = 0;
+// 
+// int calculate_answer() {
+//   ultimate_answer = 42;
+//   return 5;
+// }
+//
+// }
 
-#include <cstdio>
+// RUN: cat %s | env LD_LIBRARY_PATH=%S/Inputs:$LD_LIBRARY_PATH clang-repl | FileCheck %s
 
-extern int ultimate_answer;
-int calculate_answer();
+extern "C" int printf(const char* format, ...);
+
+extern "C" int ultimate_answer;
+extern "C" int calculate_answer();
 
 %lib libdynamic-library-test.so
 
 printf("Return value: %d\n", calculate_answer());
 // CHECK: Return value: 5
 
 printf("Variable: %d\n", ultimate_answer);
 // CHECK-NEXT: Variable: 42
 
 %quit