Pick correct GLSL version when `gl_Layer` used

`gl_Layer` as a fragment input requires at least version 4.30 of GLSL, so we try to track that information when we see the name used.

Note that this does *not* override a user-specified `#version` line.

This required re-ordering when lowering happens relative to emitting the `#version` directive, since this code works by actually modifying the chosen profile for the entry point.
Yes, that is kind of gross and we should do something cleaner in the long term.

1 files changed, 7 insertions, 3 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 8c6a46196..0eb371b88 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -3604,6 +3604,13 @@ String emitEntryPoint(
 
     auto translationUnitSyntax = translationUnit->SyntaxNode.Ptr();
 
+    // We perform lowering of the program before emitting *anything*,
+    // because the lowering process might change how we emit some
+    // boilerplate at the start of the ouput for GLSL (e.g., what
+    // version we require).
+    auto lowered = lowerEntryPoint(entryPoint, programLayout, target);
+    sharedContext.program = lowered.program;
+
 
     // There may be global-scope modifiers that we should emit now
     visitor.emitGLSLPreprocessorDirectives(translationUnitSyntax);
@@ -3624,9 +3631,6 @@ String emitEntryPoint(
         break;
     }
 
-    auto lowered = lowerEntryPoint(entryPoint, programLayout, target);
-
-    sharedContext.program = lowered.program;
 
     visitor.EmitDeclsInContainer(lowered.program.Ptr());