Support generic interface methods (#251)

* improve diagnostic messages and prevent fatal errors from crashing the compiler.

* fix top level exception catching.

* spelling fix

* change wording of invalidSwizzleExpr diagnostic

* add speculative GenericsApp expr parsing

* add new test case of cascading generics call.

* Fixing bugs in compiling cascaded generic function calls.

Add implementation of DeclaredSubTypeWitness::SubstituteImpl()

This is not needed by the type checker, but needed by IR specialization. When input source contains cascading generic function call, the arguments to `specialize` instruction is currently represented as a substitution. The arg values of this subsittution can be a `DeclaredSubTypeWitness` when a generic function uses one of its generic parameter to specialize another generic function. When the top level generics function is being specialized, this substitution argument, which is a `DeclaredSubTypeWitness`, needs to be substituted with the witness that used to specialize the top level function in the specialized specialize instruction as well.

* add a test case for cascading generic function call.

* parser bug fix

* fixes #255

* add test case for issue #255

* Generate missing `specialize` instruction when calling a generic method from an interface constraint.

When calling a generic method via an interface, we should be generating the following ir:
...
f = lookup_interface_method(...)
f_s = specailize(f, declRef)
...

This commit fixes this  `emitFuncRef` function to emit the needed `specialize` instruction.

* fixes #260

This fix follows the second apporach in the disucssion. It generated mangled name for specialized functions by appending new substitution type names to the original mangled name.

* Disabling removing and re-inserting specailized functions in getSpecalizeFunc()

I am not sure why it is needed, it seems HLSL and GLSL backends are generating forward declarations anyways, so the order of functions in IRModule shouldn't matter.

* cleanup and complete test cases.

* fix warnings

1 files changed, 5 insertions, 5 deletions

diff --git a/source/slang/slang.cpp b/source/slang/slang.cpp
index 1cda8e7d0..fe24fbd19 100644
--- a/source/slang/slang.cpp
+++ b/source/slang/slang.cpp
@@ -246,13 +246,13 @@ int CompileRequest::executeActionsInner()
     // Do some cleanup on settings specified by user.
     // In particular, we want to propagate flags from the overall request down to
     // each translation unit.
-    for( auto& translationUnit : translationUnits )
+    for (auto& translationUnit : translationUnits)
     {
         translationUnit->compileFlags |= compileFlags;
 
         // However, the "no checking" flag shouldn't be applied to
         // any translation unit that is native Slang code.
-        if( translationUnit->sourceLanguage == SourceLanguage::Slang )
+        if (translationUnit->sourceLanguage == SourceLanguage::Slang)
         {
             translationUnit->compileFlags &= ~SLANG_COMPILE_FLAG_NO_CHECKING;
         }
@@ -282,7 +282,7 @@ int CompileRequest::executeActionsInner()
     // a pass-through compilation.
     //
     // Note that we *do* perform output generation as normal in pass-through mode.
-    if( passThrough == PassThroughMode::None )
+    if (passThrough == PassThroughMode::None)
     {
         // Parse everything from the input files requested
         for (auto& translationUnit : translationUnits)
@@ -316,7 +316,7 @@ int CompileRequest::executeActionsInner()
                 return 1;
         }
     }
-    
+
     // If command line specifies to skip codegen, we exit here.
     // Note: this is a debugging option.
     if (shouldSkipCodegen)
@@ -901,7 +901,7 @@ SLANG_API int spCompile(
 {
     auto req = REQ(request);
 
-#if 0
+#if !defined(SLANG_DEBUG_INTERNAL_ERROR)
     // By default we'd like to catch as many internal errors as possible,
     // and report them to the user nicely (rather than just crash their
     // application). Internally Slang currently uses exceptions for this.