Follow symlinks when guessing compiler

This makes ccache able to guess compiler type “GCC” for a common symlink
chain like this:

    /usr/bin/cc -> /etc/alternatives/cc -> /usr/bin/gcc
    -> gcc-9 -> x86_64-linux-gnu-gcc-9

Closes #718.

1 files changed, 46 insertions, 0 deletions

diff --git a/unittest/test_ccache.cpp b/unittest/test_ccache.cpp
index ce8b79d4..93d69c5a 100644
--- a/unittest/test_ccache.cpp
+++ b/unittest/test_ccache.cpp
@@ -30,6 +30,8 @@
 #  define CCACHE_NAME "ccache"
 #endif
 
+using TestUtil::TestContext;
+
 TEST_SUITE_BEGIN("ccache");
 
 // Wraps find_compiler in a test friendly interface.
@@ -155,6 +157,50 @@ TEST_CASE("find_compiler")
   }
 }
 
+TEST_CASE("guess_compiler")
+{
+  TestContext test_context;
+
+  SUBCASE("Compiler not in file system")
+  {
+    CHECK(guess_compiler("/test/prefix/clang") == GuessedCompiler::clang);
+    CHECK(guess_compiler("/test/prefix/clang-3.8") == GuessedCompiler::clang);
+    CHECK(guess_compiler("/test/prefix/clang++") == GuessedCompiler::clang);
+    CHECK(guess_compiler("/test/prefix/clang++-10") == GuessedCompiler::clang);
+
+    CHECK(guess_compiler("/test/prefix/gcc") == GuessedCompiler::gcc);
+    CHECK(guess_compiler("/test/prefix/gcc-4.8") == GuessedCompiler::gcc);
+    CHECK(guess_compiler("/test/prefix/g++") == GuessedCompiler::gcc);
+    CHECK(guess_compiler("/test/prefix/g++-9") == GuessedCompiler::gcc);
+    CHECK(guess_compiler("/test/prefix/x86_64-w64-mingw32-gcc-posix")
+          == GuessedCompiler::gcc);
+
+    CHECK(guess_compiler("/test/prefix/nvcc") == GuessedCompiler::nvcc);
+    CHECK(guess_compiler("/test/prefix/nvcc-10.1.243")
+          == GuessedCompiler::nvcc);
+
+    CHECK(guess_compiler("/test/prefix/pump") == GuessedCompiler::pump);
+    CHECK(guess_compiler("/test/prefix/distcc-pump") == GuessedCompiler::pump);
+
+    CHECK(guess_compiler("/test/prefix/x") == GuessedCompiler::unknown);
+    CHECK(guess_compiler("/test/prefix/cc") == GuessedCompiler::unknown);
+    CHECK(guess_compiler("/test/prefix/c++") == GuessedCompiler::unknown);
+  }
+
+#ifndef _WIN32
+  SUBCASE("Follow symlink to actual compiler")
+  {
+    const auto cwd = Util::get_actual_cwd();
+    Util::write_file(FMT("{}/gcc", cwd), "");
+    CHECK(symlink("gcc", FMT("{}/intermediate", cwd).c_str()) == 0);
+    const auto cc = FMT("{}/cc", cwd);
+    CHECK(symlink("intermediate", cc.c_str()) == 0);
+
+    CHECK(guess_compiler(cc) == GuessedCompiler::gcc);
+  }
+#endif
+}
+
 TEST_CASE("rewrite_dep_file_paths")
 {
   Context ctx;