[clang] [clang][deps] Support single-file mode for all formats (PR #88764)

[Jan Svoboda via cfe-commits]

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@@ -694,38 +687,28 @@ static std::string getModuleCachePath(ArrayRef<std::string> Args) {
   return std::string(Path);
 }
 
-// getCompilationDataBase - If -compilation-database is set, load the
-// compilation database from the specified file. Otherwise if the we're
-// generating P1689 format, trying to generate the compilation database
-// form specified command line after the positional parameter "--".
+/// Attempts to construct the compilation database from '-compilation-database'
+/// or from the arguments following the positional '--'.
 static std::unique_ptr<tooling::CompilationDatabase>
-getCompilationDataBase(int argc, char **argv, std::string &ErrorMessage) {
+getCompilationDatabase(int argc, char **argv, std::string &ErrorMessage) {
   ParseArgs(argc, argv);
 
+  if (!(CommandLine.empty() ^ CompilationDB.empty())) {
+    llvm::errs() << "The compilation command line must be provided either via "
+                    "'-compilation-database' or after '--'.";
+    return nullptr;
+  }
+
   if (!CompilationDB.empty())
     return tooling::JSONCompilationDatabase::loadFromFile(
         CompilationDB, ErrorMessage,
         tooling::JSONCommandLineSyntax::AutoDetect);
 
-  if (Format != ScanningOutputFormat::P1689) {
-    llvm::errs() << "the --compilation-database option: must be specified at "
-                    "least once!";
-    return nullptr;
-  }
-
-  // Trying to get the input file, the output file and the command line options
-  // from the positional parameter "--".
-  char **DoubleDash = std::find(argv, argv + argc, StringRef("--"));
-  if (DoubleDash == argv + argc) {
-    llvm::errs() << "The command line arguments is required after '--' in "
-                    "P1689 per file mode.";
-    return nullptr;
-  }
-
   llvm::IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
       CompilerInstance::createDiagnostics(new DiagnosticOptions);
   driver::Driver TheDriver(CommandLine[0], llvm::sys::getDefaultTargetTriple(),
                            *Diags);
+  TheDriver.setCheckInputsExist(false);
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jansvoboda11 wrote:

This is here because some tests rely on the fact that we fail later and print a specific error message if the main input file doesn't exist.

https://github.com/llvm/llvm-project/pull/88764