Fixed generic interface specialization crashes (#6601): (#6688)

* Fixed generic interface specialization crashes:

- Add an export decoration to specialized generic interfaces.

* Fixed generic interface specialization crashes:

- Add an export decoration to specialized generic interfaces.
- Use getTypeNameHint(...) instead of a manual mangler.

* In cloneInstDecorationsAndChildren: specialize all linkage decorations, not just the exports.

- If a linkage decoration is already present, it is not specialized and replaced by the specialized one.
- If a specialization uses the TypeNameHint, sanitize it to be used as an identifier.
- Use the identifier name sanitizer from slang-mangle.

* Added tests/generics/generic-interface-linkage.slang

- See #6601 and #6688

4 files changed, 157 insertions, 6 deletions

diff --git a/source/slang/slang-ir-clone.cpp b/source/slang/slang-ir-clone.cpp
index 66af405d6..5bb1c1210 100644
--- a/source/slang/slang-ir-clone.cpp
+++ b/source/slang/slang-ir-clone.cpp
@@ -2,7 +2,10 @@
 #include "slang-ir-clone.h"
 
 #include "slang-ir-insts.h"
+#include "slang-ir-util.h"
 #include "slang-ir.h"
+#include "slang-mangle.h"
+
 
 namespace Slang
 {
@@ -104,6 +107,61 @@ IRInst* cloneInstAndOperands(IRCloneEnv* env, IRBuilder* builder, IRInst* oldIns
     return newInst;
 }
 
+// Copy the linkage decoration of oldInst (if present) and specialize it for target.
+static void specializeLinkageDecoration(IRInst* target, IRSpecialize* oldInst, IRBuilder* builder)
+{
+    auto gen = as<IRGeneric>(oldInst->getBase());
+    if (gen)
+    {
+        auto genLinkage = gen->findDecoration<IRLinkageDecoration>();
+        if (genLinkage)
+        {
+            bool isExport = as<IRExportDecoration>(genLinkage);
+            StringBuilder sb;
+            sb.append(genLinkage->getMangledName());
+            sb.append("G");
+            IRSpecialize* specializationProvider = oldInst;
+            if (auto targetAsSpec = as<IRSpecialize>(target))
+            {
+                specializationProvider = targetAsSpec;
+            }
+            for (UInt i = 0; i < specializationProvider->getArgCount(); ++i)
+            {
+                auto arg = specializationProvider->getArg(i);
+                sb.append(i);
+                if (auto typeLinkage = arg->findDecoration<IRLinkageDecoration>())
+                {
+                    sb.append(typeLinkage->getMangledName());
+                }
+                else
+                {
+                    // getTypeNameHint may produce a name with characters that can't
+                    // be part of an identifier, so we need to filter it afterward.
+                    StringBuilder tmp;
+                    getTypeNameHint(tmp, arg);
+                    emitNameForLinkage(sb, tmp.getUnownedSlice());
+                }
+            }
+            if (auto previousLinkage = target->findDecoration<IRLinkageDecoration>())
+            {
+                // Overwrite the previous linkage decoration, since it was not specialized
+                previousLinkage->setOperand(0, builder->getStringValue(sb.getUnownedSlice()));
+            }
+            else
+            {
+                if (isExport)
+                {
+                    builder->addExportDecoration(target, sb.getUnownedSlice());
+                }
+                else
+                {
+                    builder->addImportDecoration(target, sb.getUnownedSlice());
+                }
+            }
+        }
+    }
+}
+
 // The complexity of the second phase of cloning (the
 // one that deals with decorations and children) comes
 // from the fact that it needs to sequence the two phases
@@ -226,6 +284,11 @@ static void _cloneInstDecorationsAndChildren(
         newParam->setFullType(newType);
         newParam->sourceLoc = oldParam->sourceLoc;
     }
+
+    if (auto oldAsSpec = as<IRSpecialize>(oldInst))
+    {
+        specializeLinkageDecoration(newInst, oldAsSpec, builder);
+    }
 }
 
 // The public version of `cloneInstDecorationsAndChildren` is then
diff --git a/source/slang/slang-mangle.cpp b/source/slang/slang-mangle.cpp
index 12e185c8b..63dfffb94 100644
--- a/source/slang/slang-mangle.cpp
+++ b/source/slang/slang-mangle.cpp
@@ -31,7 +31,7 @@ void emit(ManglingContext* context, String const& value)
     context->sb.append(value);
 }
 
-void emitNameImpl(ManglingContext* context, UnownedStringSlice str)
+void emitNameForLinkage(StringBuilder& sb, UnownedStringSlice str)
 {
     Index length = str.getLength();
     // If the name consists of only traditional "identifer characters"
@@ -61,8 +61,8 @@ void emitNameImpl(ManglingContext* context, UnownedStringSlice str)
         // code points and the number of extended grapheme clusters,
         // since the entire name is within the ASCII subset.
         //
-        emit(context, length);
-        context->sb.append(str);
+        sb.append(length);
+        sb.append(str);
     }
     else
     {
@@ -98,9 +98,9 @@ void emitNameImpl(ManglingContext* context, UnownedStringSlice str)
             }
         }
 
-        context->sb.append("R");
-        emit(context, encoded.getLength());
-        context->sb.append(encoded);
+        sb.append("R");
+        sb.append(encoded.getLength());
+        sb.append(encoded);
     }
 
     // TODO: This logic does not rule out consecutive underscores,
@@ -111,6 +111,11 @@ void emitNameImpl(ManglingContext* context, UnownedStringSlice str)
     // target, rather than adding complexity here.
 }
 
+void emitNameImpl(ManglingContext* context, UnownedStringSlice str)
+{
+    emitNameForLinkage(context->sb, str);
+}
+
 void emitName(ManglingContext* context, Name* name)
 {
     String str = getText(name);
diff --git a/source/slang/slang-mangle.h b/source/slang/slang-mangle.h
index cfdbe461b..079f7c02d 100644
--- a/source/slang/slang-mangle.h
+++ b/source/slang/slang-mangle.h
@@ -10,6 +10,8 @@ namespace Slang
 {
 struct IRSpecialize;
 
+void emitNameForLinkage(StringBuilder& sb, UnownedStringSlice str);
+
 String getMangledName(ASTBuilder* astBuilder, Decl* decl);
 String getMangledName(ASTBuilder* astBuilder, DeclRefBase* declRef);
 String getMangledNameFromNameString(const UnownedStringSlice& name);
diff --git a/tests/language-feature/generics/generic-interface-linkage.slang b/tests/language-feature/generics/generic-interface-linkage.slang
new file mode 100644
index 000000000..657ac3d48
--- /dev/null
+++ b/tests/language-feature/generics/generic-interface-linkage.slang
@@ -0,0 +1,81 @@
+
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK):-slang -compute -shaderobj -output-using-type
+//TEST(compute, vulkan):COMPARE_COMPUTE(filecheck-buffer=CHECK):-vk -compute -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+interface IGetter
+{
+    float get(uint id);
+}
+
+struct GetterImpl : IGetter
+{
+    float[8] data;
+
+    __init(float[8] data)
+    { this.data = data; }
+
+    float get(uint id)
+    {
+        return data[id];
+    }
+}
+interface IFoo<int N>
+{
+    associatedtype Params : IGetter;
+
+    Params bar();
+}
+
+struct FooImpl1: IFoo<8>
+{   
+    typealias Params = GetterImpl;
+
+    __init()
+    { }
+
+    Params bar()
+    {
+        float x = outputBuffer[0];
+        return GetterImpl({x, x+1, x+2, x+3, x+4, x+5, x+6, x+7});
+    }
+}
+
+struct FooImpl2: IFoo<8>
+{
+    typealias Params = GetterImpl;
+
+    __init()
+    { }
+
+    Params bar()
+    {
+        float x = 2 * outputBuffer[0];
+        return GetterImpl({x+3, x+5, x+7, x+9, x+11, x+13, x+15, x+17});
+    }
+}
+
+IFoo<8> getFoo(uint id)
+{
+    if (id == 0)
+        return FooImpl1();
+    else
+        return FooImpl2();
+}
+
+float doThing(uint id)
+{
+    IFoo<8> foo = getFoo(id);
+    return foo.bar().get(0);
+}
+
+[shader("compute")]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    // CHECK: 0
+    outputBuffer[0] = doThing(0);
+	// CHECK: 3
+    outputBuffer[1] = doThing(1);
+}
\ No newline at end of file