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, 8 insertions, 0 deletions

diff --git a/source/slangc/main.cpp b/source/slangc/main.cpp
index a97c38685..6fb394cce 100644
--- a/source/slangc/main.cpp
+++ b/source/slangc/main.cpp
@@ -3,6 +3,8 @@
 #define SLANG_DYNAMIC
 #include "../slang.h"
 
+SLANG_API void spSetCommandLineCompilerMode(SlangCompileRequest* request);
+
 #include "core/slang-io.h"
 
 using namespace Slang;
@@ -32,6 +34,8 @@ int MAIN(int argc, char** argv)
     SlangSession* session = spCreateSession(nullptr);
     SlangCompileRequest* compileRequest = spCreateCompileRequest(session);
 
+    spSetCommandLineCompilerMode(compileRequest);
+
     char const* appName = "slangc";
     if(argc > 0) appName = argv[0];
 
@@ -62,6 +66,9 @@ int MAIN(int argc, char** argv)
             exit(-1);
         }
 
+#if 0
+        // Produce output as the command-line compiler driver should.
+
         // Now dump the output from the compilation to stdout.
         //
         // TODO: Need a way to control where output goes so that
@@ -76,6 +83,7 @@ int MAIN(int argc, char** argv)
             fputs(output, stdout);
         }
         fflush(stdout);
+#endif
 
         // Now that we are done, clean up after ourselves