debug: Add trace logging to identify out-of-project files (#409)

When investigating a customer issue, we're running into a mysterious
bug where seemingly in-project files are being considered out-of-project.
We add support for a 'trace' logging level to debug this issue,
as this logging shouldn't be needed for most debugging cases.

The trace logging level is not yet documented as we may remove it
later.

Author: varungandhi-src

indexer/IdPathMappings.cc

@@ -11,6 +11,7 @@
 #include "indexer/FileMetadata.h"
 #include "indexer/Hash.h"
 #include "indexer/IdPathMappings.h"
+#include "indexer/LlvmAdapter.h"
 #include "indexer/Path.h"
 
 namespace scip_clang {
@@ -127,14 +128,43 @@ bool FileMetadataMap::insert(clang::FileID fileId, AbsolutePathRef absPathRef) {
     // projectRoot / relativePath exists, but is actually a symlink to
     // inside the build root, rather than an in-project file. So check that
     // that real_path is the same.
-    if (!error && realPath.str() == originalFileSourcePath.asStringRef()) {
-      return insertRelPath(RootRelativePathRef(buildRootRelPath->asStringView(),
-                                               RootKind::Project),
-                           /*isInProject*/ true);
+    if (!error) {
+      if (realPath.str() == originalFileSourcePath.asStringRef()) {
+        return insertRelPath(
+            RootRelativePathRef(buildRootRelPath->asStringView(),
+                                RootKind::Project),
+            /*isInProject*/ true);
+      } else {
+        spdlog::trace("projectRoot.join(relativePath (= '{}'/'{}')) exists but "
+                      "the real path is '{}",
+                      this->projectRootPath.asRef().asStringView(),
+                      buildRootRelPath->asStringView(),
+                      llvm_ext::toStringView(realPath.str()));
+      }
+    } else if (error == std::errc::no_such_file_or_directory) {
+      spdlog::trace(
+          "failed to find file in project at '{}' (root: '{}', rel: '{}')",
+          originalFileSourcePath.asStringRef(),
+          this->projectRootPath.asRef().asStringView(),
+          buildRootRelPath->asStringView());
+    } else {
+      spdlog::trace("hit error: {} when getting real path for {}",
+                    error.message(), originalFileSourcePath.asStringRef());
     }
   } else if (auto optProjectRootRelPath =
                  this->projectRootPath.tryMakeRelative(absPathRef)) {
     return insertRelPath(optProjectRootRelPath.value(), /*isInProject*/ true);
+  } else {
+    if ((spdlog::default_logger_raw()->level() <= spdlog::level::trace)
+        && (absPathRef.asStringView().find("usr/include") == std::string::npos)
+        && (absPathRef.asStringView().find("usr/lib/clang")
+            == std::string::npos)) {
+      spdlog::trace(
+          "path {} is neither inside project root {} nor inside build root {}",
+          absPathRef.asStringView(),
+          this->projectRootPath.asRef().asStringView(),
+          this->buildRootPath.asRef().asStringView());
+    }
   }
 
   auto optFileName = absPathRef.fileName();

indexer/main.cc

@@ -179,7 +179,9 @@ static scip_clang::CliOptions parseArguments(int argc, char *argv[]) {
   cliOptions.showProgress = result.count("no-progress-report") == 0;
 
   auto level = result["log-level"].as<std::string>();
-  if (level == "debug") {
+  if (level == "trace") {
+    cliOptions.logLevel = spdlog::level::level_enum::trace;
+  } else if (level == "debug") {
     cliOptions.logLevel = spdlog::level::level_enum::debug;
   } else if (level == "info") {
     cliOptions.logLevel = spdlog::level::level_enum::info;