Fixed logic, and added default to stdout if stdin is used

Also:
- re-ran self-build and regression tests
- suppressed non-error output when stdout is used, so piping is easier

source/common.h

@@ -800,7 +800,7 @@ class cmdline_processor
         );
 
         print("\nUsage: cppfront [options] file ...\n");
-        print("\nfile - The source file(s) to compile (can be 'stdin' to read text directly) \n");
+        print("\n  file                    source file(s) (can be 'stdin')\n");
         print("\nOptions: \n");
         int last_group = -1;
         for (auto& flag : flags) {

source/cppfront.cpp

@@ -79,7 +79,12 @@ auto main(
 
         auto& out = flag_cpp1_filename != "stdout" ? std::cout : std::cerr;
 
-        if (!flag_quiet) {
+        if (
+            !flag_quiet
+            && arg.text != "stdin"
+            && flag_cpp1_filename != "stdout"
+            ) 
+        {
             out << arg.text << "...";
         }
 
@@ -92,7 +97,10 @@ auto main(
         //  If there were no errors, say so and generate Cpp1
         if (c.had_no_errors())
         {
-            if (!flag_quiet)
+            if (
+                !flag_quiet
+                && flag_cpp1_filename != "stdout"
+                )
             {
                 if (!c.has_cpp1()) {
                     out << " ok (all Cpp2, passes safety checks)\n";

source/io.h

@@ -886,7 +886,7 @@ class source
         //
         auto is_stdin = filename == "stdin";
         std::ifstream fss;
-        if (is_stdin) 
+        if (!is_stdin) 
         {
             fss.open(filename);
             if( !fss.is_open()) { return false; }

source/to_cpp1.h

@@ -1258,14 +1258,18 @@ class cppfront
         }
 
         //  Now we'll open the Cpp1 file
-        auto cpp1_filename = sourcefile.substr(0, std::ssize(sourcefile) - 1);
+        //  Default to stdout if input is stdin
+        auto cpp1_filename = std::string{"stdout"};
+        if (sourcefile != "stdin") {
+            assert(sourcefile.ends_with("2"));
+            cpp1_filename = sourcefile.substr(0, std::ssize(sourcefile) - 1);
+        }
 
-        //  Use explicit filename override if present,
-        //  otherwise strip leading path
+        //  Use explicit filename override if present, otherwise strip leading path
         if (!flag_cpp1_filename.empty()) {
             cpp1_filename = flag_cpp1_filename;
         }
-        else {
+        else if (cpp1_filename != "stdout") {
             cpp1_filename = std::filesystem::path(cpp1_filename).filename().string();
         }