[NFC][Driver] Change SYCL test file extension .c -> .cpp (#20977)

SYCL is an API built on top of C++ programming language. Building SYCL
program with C compiler is not possible.

The content of clang/test/Driver/sycl-offload-old-model.c test has been
added to existing clang/test/Driver/sycl-offload-old-model.cpp test.
The same applies to clang/test/Driver/sycl-offload.c.

Moved a check for a warning about using .c file extenion for SYCL to a
separate test - clang/test/Driver/sycl-c-warn.c.

Author: bader

…st/CodeGen/sycl-instrumentation-option.c …/CodeGen/sycl-instrumentation-option.cppclang/test/CodeGen/sycl-instrumentation-option.c renamed to clang/test/CodeGen/sycl-instrumentation-option.cpp clang/test/CodeGen/sycl-instrumentation-option.c renamed to clang/test/CodeGen/sycl-instrumentation-option.cpp

@@ -0,0 +1,9 @@
+// Emit warning for treating 'c' input as 'c++' when -fsycl is used
+// RUN: %clang -### -fsycl %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// RUN: %clang_cl -### -fsycl %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// RUN: %clang -### -fsycl --offload-new-driver  %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// RUN: %clang_cl -### -fsycl --offload-new-driver  %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// RUN: %clang -### -fsycl --no-offload-new-driver  %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// RUN: %clang_cl -### -fsycl --no-offload-new-driver  %s 2>&1 | FileCheck -check-prefix FSYCL-CHECK %s
+// FSYCL-CHECK: warning: treating 'c' input as 'c++' when -fsycl is used [-Wexpected-file-type]
+

…ng/test/Driver/openmp-simd-sycl-device.c …/test/Driver/openmp-simd-sycl-device.cppclang/test/Driver/openmp-simd-sycl-device.c renamed to clang/test/Driver/openmp-simd-sycl-device.cpp clang/test/Driver/openmp-simd-sycl-device.c renamed to clang/test/Driver/openmp-simd-sycl-device.cpp

@@ -6,8 +6,8 @@
 
 /// Test behaviors of using a static library with single object.
 // Build the offload library that is used for the tests.
-// RUN: echo "void foo() {}" > %t.c
-// RUN: %clang_cl --target=x86_64-pc-windows-msvc -fsycl --no-offload-new-driver -c -Fo%t-orig.obj %t.c
+// RUN: echo "void foo() {}" > %t.cpp
+// RUN: %clang_cl --target=x86_64-pc-windows-msvc -fsycl --no-offload-new-driver -c -Fo%t-orig.obj %t.cpp
 // RUN: llvm-ar cr %t-orig.lib %t-orig.obj
 // RUN: %clang --target=x86_64-pc-windows-msvc -fsycl --no-offload-new-driver -fno-sycl-instrument-device-code --no-offloadlib %t-orig.lib %t-orig.obj -### 2>&1 \
 // RUN:   | FileCheck %s -check-prefix=FOFFLOAD_STATIC_LIB
@@ -85,7 +85,7 @@
 // RUN: %clang_cl --target=x86_64-pc-windows-msvc -fsycl --no-offload-new-driver -fno-sycl-instrument-device-code --no-offloadlib %t-orig.lib -ccc-print-phases %s 2>&1 \
 // RUN:   | FileCheck %s -check-prefix=FOFFLOAD_STATIC_LIB_SRC
 // FOFFLOAD_STATIC_LIB_SRC: 0: input, "[[INPUTLIB:.+\.lib]]", object, (host-sycl)
-// FOFFLOAD_STATIC_LIB_SRC: 1: input, "[[INPUTC:.+\.c]]", c++, (host-sycl)
+// FOFFLOAD_STATIC_LIB_SRC: 1: input, "[[INPUTC:.+\.cpp]]", c++, (host-sycl)
 // FOFFLOAD_STATIC_LIB_SRC: 2: preprocessor, {1}, c++-cpp-output, (host-sycl)
 // FOFFLOAD_STATIC_LIB_SRC: 3: input, "[[INPUTC]]", c++, (device-sycl)
 // FOFFLOAD_STATIC_LIB_SRC: 4: preprocessor, {3}, c++-cpp-output, (device-sycl)