Swift: extract only primary files

While the (removed) comment is correct and the frontend can be called in
different modes, both `swift build` and `xcodebuild` always use
`-primary-files` when compiling Swift projects.
The other mode was present only within our test runner (`qltest.sh`), so
removing it and doing what the official build systems do simplifies our
code base.

Additionally, file archival is now a separate function/operation.

Author: AlexDenisov

swift/extractor/SwiftExtractor.cpp

@@ -18,9 +18,7 @@
 
 using namespace codeql;
 
-static void extractFile(const SwiftExtractorConfiguration& config,
-                        swift::CompilerInstance& compiler,
-                        swift::SourceFile& file) {
+static void archiveFile(const SwiftExtractorConfiguration& config, swift::SourceFile* file) {
   if (std::error_code ec = llvm::sys::fs::create_directories(config.trapDir)) {
     std::cerr << "Cannot create TRAP directory: " << ec.message() << "\n";
     return;
@@ -31,7 +29,7 @@ static void extractFile(const SwiftExtractorConfiguration& config,
     return;
   }
 
-  llvm::SmallString<PATH_MAX> srcFilePath(file.getFilename());
+  llvm::SmallString<PATH_MAX> srcFilePath(file->getFilename());
   llvm::sys::fs::make_absolute(srcFilePath);
 
   llvm::SmallString<PATH_MAX> dstFilePath(config.sourceArchiveDir);
@@ -49,12 +47,16 @@ static void extractFile(const SwiftExtractorConfiguration& config,
               << dstFilePath.str().str() << "': " << ec.message() << "\n";
     return;
   }
+}
 
+static void extractFile(const SwiftExtractorConfiguration& config,
+                        swift::CompilerInstance& compiler,
+                        swift::SourceFile* file) {
   // The extractor can be called several times from different processes with
   // the same input file(s)
   // We are using PID to avoid concurrent access
   // TODO: find a more robust approach to avoid collisions?
-  std::string tempTrapName = file.getFilename().str() + '.' + std::to_string(getpid()) + ".trap";
+  std::string tempTrapName = file->getFilename().str() + '.' + std::to_string(getpid()) + ".trap";
   llvm::SmallString<PATH_MAX> tempTrapPath(config.trapDir);
   llvm::sys::path::append(tempTrapPath, tempTrapName);
 
@@ -84,17 +86,20 @@ static void extractFile(const SwiftExtractorConfiguration& config,
 
   // In the case of emtpy files, the dispatcher is not called, but we still want to 'record' the
   // fact that the file was extracted
+  // TODO: to be moved elsewhere
+  llvm::SmallString<PATH_MAX> srcFilePath(file->getFilename());
+  llvm::sys::fs::make_absolute(srcFilePath);
   auto fileLabel = arena.allocateLabel<FileTag>();
   trap.assignKey(fileLabel, srcFilePath.str().str());
   trap.emit(FilesTrap{fileLabel, srcFilePath.str().str()});
 
   SwiftVisitor visitor(compiler.getSourceMgr(), arena, trap);
-  for (swift::Decl* decl : file.getTopLevelDecls()) {
+  for (swift::Decl* decl : file->getTopLevelDecls()) {
     visitor.extract(decl);
   }
 
   // TODO: Pick a better name to avoid collisions
-  std::string trapName = file.getFilename().str() + ".trap";
+  std::string trapName = file->getFilename().str() + ".trap";
   llvm::SmallString<PATH_MAX> trapPath(config.trapDir);
   llvm::sys::path::append(trapPath, trapName);
 
@@ -107,19 +112,8 @@ static void extractFile(const SwiftExtractorConfiguration& config,
 
 void codeql::extractSwiftFiles(const SwiftExtractorConfiguration& config,
                                swift::CompilerInstance& compiler) {
-  // Swift frontend can be called in several different modes, we are interested
-  // only in the cases when either a primary or a main source file is present
-  if (compiler.getPrimarySourceFiles().empty()) {
-    swift::ModuleDecl* module = compiler.getMainModule();
-    if (!module->getFiles().empty() &&
-        module->getFiles().front()->getKind() == swift::FileUnitKind::Source) {
-      // We can only call getMainSourceFile if the first file is of a Source kind
-      swift::SourceFile& file = module->getMainSourceFile();
-      extractFile(config, compiler, file);
-    }
-  } else {
-    for (auto s : compiler.getPrimarySourceFiles()) {
-      extractFile(config, compiler, *s);
-    }
+  for (auto s : compiler.getPrimarySourceFiles()) {
+    archiveFile(config, s);
+    extractFile(config, compiler, s);
   }
 }

swift/tools/qltest.sh

@@ -7,5 +7,5 @@ QLTEST_LOG="$CODEQL_EXTRACTOR_SWIFT_LOG_DIR"/qltest.log
 export LD_LIBRARY_PATH="$CODEQL_EXTRACTOR_SWIFT_ROOT/tools/$CODEQL_PLATFORM"
 
 for src in *.swift; do
-  "$CODEQL_EXTRACTOR_SWIFT_ROOT/tools/$CODEQL_PLATFORM/extractor" -sdk "$CODEQL_EXTRACTOR_SWIFT_ROOT/qltest/$CODEQL_PLATFORM/sdk" -c $src >> $QLTEST_LOG 2>&1
+  "$CODEQL_EXTRACTOR_SWIFT_ROOT/tools/$CODEQL_PLATFORM/extractor" -sdk "$CODEQL_EXTRACTOR_SWIFT_ROOT/qltest/$CODEQL_PLATFORM/sdk" -c -primary-file $src >> $QLTEST_LOG 2>&1
 done