Add a `-o` option to command-line `slangc`

Fixes #11

- This adds a `-o` command-line option for specifying an output file.

- The code tries to be a bit smart, to glean an output format from a file extension, and also to associate multiple `-o` options with multiple `-entry` options if needed.

- There is a restriction that all the output files need to agree on the code generation target. This is reasonable for now, but might be something to lift eventualy

- There is a restriction that only one output file is allowed per entry point
  - Together with the previous item this means you can't output both a `.spv` and a `.spv.asm` in one pass, even though both should be possible

- There is currently a restriction that output paths only apply to entry points
  - This means there is no way to output reflection JSON to a file with `-o` (but that is mostly just a debugging feature for now)
  - This also means we don't support any "container" formats that can encapsulate multiple compiled entry points

1 files changed, 7 insertions, 0 deletions

diff --git a/source/slang/compiler.h b/source/slang/compiler.h
index 09797664f..180fb027a 100644
--- a/source/slang/compiler.h
+++ b/source/slang/compiler.h
@@ -102,6 +102,10 @@ namespace Slang
         // supposed to be defined in.
         int translationUnitIndex;
 
+        // The output path requested for this entry point.
+        // (only used when compiling from the command line)
+        String outputPath;
+
         // The resulting output for the enry point
         //
         // TODO: low-level code generation should be a distinct step
@@ -221,6 +225,9 @@ namespace Slang
         // How should `#line` directives be emitted (if at all)?
         LineDirectiveMode lineDirectiveMode = LineDirectiveMode::Default;
 
+        // Are we being driven by the command-line `slangc`, and should act accordingly?
+        bool isCommandLineCompile = false;
+
         // Output stuff
         DiagnosticSink mSink;
         String mDiagnosticOutput;