[test] Improve tests for alias/ifunc attributes

Author: MaskRay

clang/test/Sema/alias-unused-win.cpp

@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -triple %ms_abi_triple -Wunused -x c -verify %s
+// RUN: %clang_cc1 -triple %ms_abi_triple -Wunused -verify=expected,cxx %s
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+static int f(void) { return 42; } // cxx-warning{{unused function 'f'}}
+int g(void) __attribute__((alias("f")));
+
+static int foo [] = { 42, 0xDEAD }; // cxx-warning{{variable 'foo' is not needed and will not be emitted}}
+extern typeof(foo) bar __attribute__((unused, alias("foo")));
+
+static int __attribute__((overloadable)) f0(int x) { return x; } // expected-warning{{unused function 'f0'}}
+static float __attribute__((overloadable)) f0(float x) { return x; } // expected-warning{{unused function 'f0'}}
+int g0(void) __attribute__((alias("?f0@@YAHH@Z")));
+
+#ifdef __cplusplus
+/// https://github.com/llvm/llvm-project/issues/88593
+/// We report a warning in C++ mode because the internal linkage `resolver` gets
+/// mangled as it does not have a language linkage. GCC does not mangle
+/// `resolver` or report a warning.
+static int f1() { return 42; } // cxx-warning{{unused function 'f1'}}
+int g1(void) __attribute__((alias("?f1@@YAHXZ")));
+}
+
+namespace ns {
+static int f3(int) { return 42; } // cxx-warning{{unused function 'f3'}}
+static int f3() { return 42; } // cxx-warning{{unused function 'f3'}}
+int g3() __attribute__((alias("?f3@ns@@YAHXZ")));
+}
+#endif

clang/test/Sema/alias-unused.c

@@ -0,0 +1,50 @@
+// RUN: %clang_cc1 -triple %itanium_abi_triple -Wunused -x c -verify %s
+// RUN: %clang_cc1 -triple %itanium_abi_triple -Wunused -verify=expected,cxx %s
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+static int f(void) { return 42; }
+int g(void) __attribute__((alias("f")));
+
+static int foo [] = { 42, 0xDEAD }; // cxx-warning{{variable 'foo' is not needed and will not be emitted}}
+extern typeof(foo) bar __attribute__((unused, alias("foo")));
+
+/// https://github.com/llvm/llvm-project/issues/88593
+/// We report a warning in C++ mode because the internal linkage `resolver` gets
+/// mangled as it does not have a language linkage. GCC does not mangle
+/// `resolver` or report a warning.
+static int (*resolver(void))(void) { return f; } // expected-warning{{unused function 'resolver'}}
+int ifunc(void) __attribute__((ifunc("resolver")));
+
+static int __attribute__((overloadable)) f0(int x) { return x; } // expected-warning{{unused function 'f0'}}
+static float __attribute__((overloadable)) f0(float x) { return x; } // expected-warning{{unused function 'f0'}}
+int g0(void) __attribute__((alias("_ZL2f0i")));
+
+#ifdef __cplusplus
+static int f1() { return 42; } // expected-warning{{unused function 'f1'}}
+int g1(void) __attribute__((alias("_ZL2f1v")));
+}
+
+static int f2(int) { return 42; } // expected-warning{{unused function 'f2'}}
+static int f2() { return 42; } // expected-warning{{unused function 'f2'}}
+int g2() __attribute__((alias("_ZL2f2v")));
+
+static int (*resolver1())() { return f; } // expected-warning{{unused function 'resolver1'}}
+static int (*resolver1(int))() { return f; } // expected-warning{{unused function 'resolver1'}}
+int ifunc1() __attribute__((ifunc("_ZL9resolver1i")));
+
+/// TODO: We should report "unused function" for f3(int).
+namespace ns {
+static int f3(int) { return 42; } // cxx-warning{{unused function 'f3'}}
+static int f3() { return 42; } // cxx-warning{{unused function 'f3'}}
+int g3() __attribute__((alias("_ZN2nsL2f3Ev")));
+}
+
+template <class T>
+static void *f4(T) { return nullptr; }
+static void *f4() { return nullptr; } // cxx-warning{{unused function 'f4'}}
+extern void g4_int() __attribute__((ifunc("_ZL2f4IiEPvT_")));
+extern void g4_char() __attribute__((ifunc("_ZL2f4IcEPcT_"))); // rejected by CodeGen
+void *use4 = f4(0);
+#endif