[clang] [clang] Implement CTAD for type alias template. (PR #77890)

[via cfe-commits]

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@@ -2258,6 +2260,94 @@ class ExtractTypeForDeductionGuide
   }
 };
 
+// Build a deduction guide with the specified parameter types.
+FunctionTemplateDecl *
+buildDeductionGuide(Sema &SemaRef, TemplateDecl *OriginalTemplate,
+                    TemplateParameterList *TemplateParams,
+                    CXXConstructorDecl *Ctor, ExplicitSpecifier ES,
+                    TypeSourceInfo *TInfo, SourceLocation LocStart,
+                    SourceLocation Loc, SourceLocation LocEnd, bool IsImplicit,
+                    llvm::ArrayRef<TypedefNameDecl *> MaterializedTypedefs = {}) {
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cor3ntin wrote:

I missed that was pre existing, (but they are pretty bad names!)

https://github.com/llvm/llvm-project/pull/77890