[clang] [clang] CTAD: Generate deduction guides for alias templates from non-template explicit deduction guides (PR #96686)

[Younan Zhang via cfe-commits]

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@@ -3216,6 +3226,44 @@ void DeclareImplicitDeductionGuidesForTypeAlias(
   Guides.suppressDiagnostics();
 
   for (auto *G : Guides) {
+    if (auto *DG = dyn_cast<CXXDeductionGuideDecl>(G)) {
+      // The deduction guide is a non-template function decl, we just clone it.
+      auto *FunctionType =
+          SemaRef.Context.getTrivialTypeSourceInfo(DG->getType());
+      FunctionProtoTypeLoc FPTL =
+          FunctionType->getTypeLoc().castAs<FunctionProtoTypeLoc>();
+
+      // Clone the parameters.
+      unsigned ProcessedParamIndex = 0;
+      for (auto *P : DG->parameters()) {
----------------
zyn0217 wrote:

nit: I think we can just use
```cpp
for (unsigned I = 0; N = DG->parameters().size(); I != N; ++I)
```

https://github.com/llvm/llvm-project/pull/96686