Reland [clang] [unittest] Add a test for Generic_GCC::GCCVersion::Parse (#69078)

This adds actual test cases for all the cases that are listed in a code
comment in the implementation of this function; having such test
coverage eases doing further modifications to the function.

This relands b4b35a5. This time,
the new test is excluded if building with dylibs or shared libraries
enabled, as the clang::toolchains::Generic_GCC class is marked
LLVM_LIBRARY_VISIBILITY, giving it hidden visibility in such builds,
making it unreferencable outside of the dylib/shared library.

Author: mstorsjo

clang/unittests/Driver/CMakeLists.txt

@@ -9,6 +9,7 @@ set(LLVM_LINK_COMPONENTS
 add_clang_unittest(ClangDriverTests
   DistroTest.cpp
   DXCModeTest.cpp
+  GCCVersionTest.cpp
   ToolChainTest.cpp
   ModuleCacheTest.cpp
   MultilibBuilderTest.cpp

clang/unittests/Driver/GCCVersionTest.cpp

@@ -0,0 +1,59 @@
+//===- unittests/Driver/GCCVersionTest.cpp --- GCCVersion parser tests ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Unit tests for Generic_GCC::GCCVersion
+//
+//===----------------------------------------------------------------------===//
+
+#include "../../lib/Driver/ToolChains/Gnu.h"
+#include "gtest/gtest.h"
+
+// The Generic_GCC class is hidden in dylib/shared library builds, so
+// this test can only be built if neither of those configurations are
+// enabled.
+#if !defined(LLVM_BUILD_LLVM_DYLIB) && !defined(LLVM_BUILD_SHARED_LIBS)
+
+using namespace clang;
+using namespace clang::driver;
+
+namespace {
+
+struct VersionParseTest {
+  std::string Text;
+
+  int Major, Minor, Patch;
+  std::string MajorStr, MinorStr, PatchSuffix;
+};
+
+const VersionParseTest TestCases[] = {
+    {"5", 5, -1, -1, "5", "", ""},
+    {"4.4", 4, 4, -1, "4", "4", ""},
+    {"4.4-patched", 4, 4, -1, "4", "4", "-patched"},
+    {"4.4.0", 4, 4, 0, "4", "4", ""},
+    {"4.4.x", 4, 4, -1, "4", "4", ""},
+    {"4.4.2-rc4", 4, 4, 2, "4", "4", "-rc4"},
+    {"4.4.x-patched", 4, 4, -1, "4", "4", ""},
+    {"not-a-version", -1, -1, -1, "", "", ""},
+};
+
+TEST(GCCVersionTest, Parse) {
+  for (const auto &TC : TestCases) {
+    auto V = toolchains::Generic_GCC::GCCVersion::Parse(TC.Text);
+    EXPECT_EQ(V.Text, TC.Text);
+    EXPECT_EQ(V.Major, TC.Major);
+    EXPECT_EQ(V.Minor, TC.Minor);
+    EXPECT_EQ(V.Patch, TC.Patch);
+    EXPECT_EQ(V.MajorStr, TC.MajorStr);
+    EXPECT_EQ(V.MinorStr, TC.MinorStr);
+    EXPECT_EQ(V.PatchSuffix, TC.PatchSuffix);
+  }
+}
+
+} // end anonymous namespace
+
+#endif