If a locator is not set for a DownstreamCompiler type, that doesn't *necessarily* mean that there isn't one, for example with the GENERIC_C_CPP option. This could also be fixed by say giving this type an empty locator, or special casing. The option chosen here, is to allow lookup even if there isn't a locator. Note that there is some special case handling, where a generic lookup, will prime all of the specific types. (shader-slang#1154)

Author: jsmall-zzz

source/slang/slang-check.cpp

@@ -126,17 +126,15 @@ namespace Slang
 
         // Do we have a locator
         auto locator = m_downstreamCompilerLocators[int(type)];
-        if (!locator)
+        if (locator)
         {
-            return nullptr;
-        }
+            m_downstreamCompilerSet->remove(SlangPassThrough(type));
 
-        m_downstreamCompilerSet->remove(SlangPassThrough(type));
+            SinkSharedLibraryLoader loader(m_sharedLibraryLoader, sink);
+            locator(m_downstreamCompilerPaths[int(type)], &loader, m_downstreamCompilerSet);
 
-        SinkSharedLibraryLoader loader(m_sharedLibraryLoader, sink);
-        locator(m_downstreamCompilerPaths[int(type)], &loader, m_downstreamCompilerSet);
-
-        DownstreamCompilerUtil::updateDefaults(m_downstreamCompilerSet);
+            DownstreamCompilerUtil::updateDefaults(m_downstreamCompilerSet);
+        }
 
         DownstreamCompiler* compiler = nullptr;