Implement most of N3638 (return type deduction for normal functions).

Missing (somewhat ironically) is support for the new deduction rules
in lambda functions, plus PCH support for return type patching.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181108 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 30 insertions, 2 deletions

diff --git a/include/clang/AST/ASTContext.h b/include/clang/AST/ASTContext.h
index 65f29c4815..902ded55f8 100644
--- a/include/clang/AST/ASTContext.h
+++ b/include/clang/AST/ASTContext.h
@@ -867,6 +867,9 @@ public:
   const FunctionType *adjustFunctionType(const FunctionType *Fn,
                                          FunctionType::ExtInfo EInfo);
 
+  /// \brief Change the result type of a function type once it is deduced.
+  void adjustDeducedFunctionResultType(FunctionDecl *FD, QualType ResultType);
+
   /// \brief Return the uniqued reference to the type for a complex
   /// number with the specified element type.
   QualType getComplexType(QualType T) const;
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index d7347e9c31..23e4edf09d 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1477,6 +1477,23 @@ def err_decltype_auto_compound_type : Error<
 def err_decltype_auto_initializer_list : Error<
   "cannot deduce 'decltype(auto)' from initializer list">;
 
+// C++1y deduced return types
+def err_auto_fn_deduction_failure : Error<
+  "cannot deduce return type %0 from returned value of type %1">;
+def err_auto_fn_different_deductions : Error<
+  "'%select{auto|decltype(auto)}0' in return type deduced as %1 here but "
+  "deduced as %2 in earlier return statement">;
+def err_auto_fn_used_before_defined : Error<
+  "function %0 with deduced return type cannot be used before it is defined">;
+def err_auto_fn_no_return_but_not_auto : Error<
+  "cannot deduce return type %0 for function with no return statements">;
+def err_auto_fn_return_void_but_not_auto : Error<
+  "cannot deduce return type %0 from omitted return expression">;
+def err_auto_fn_return_init_list : Error<
+  "cannot deduce return type from initializer list">;
+def err_auto_fn_virtual : Error<
+  "function with deduced return type cannot be virtual">;
+
 // C++11 override control
 def override_keyword_only_allowed_on_virtual_member_functions : Error<
   "only virtual member functions can be marked '%0'">;
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 78b9f1ee5a..0e6cc440ea 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -5667,8 +5667,16 @@ public:
 
   DeduceAutoResult DeduceAutoType(TypeSourceInfo *AutoType, Expr *&Initializer,
                                   QualType &Result);
+  DeduceAutoResult DeduceAutoType(TypeLoc AutoTypeLoc, Expr *&Initializer,
+                                  QualType &Result);
   QualType SubstAutoType(QualType TypeWithAuto, QualType Replacement);
   void DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init);
+  bool DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
+                        bool Diagnose = true);
+
+  bool DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
+                                        SourceLocation ReturnLoc,
+                                        Expr *&RetExpr, AutoType *AT);
 
   FunctionTemplateDecl *getMoreSpecializedTemplate(FunctionTemplateDecl *FT1,
                                                    FunctionTemplateDecl *FT2,
diff --git a/include/clang/Sema/TemplateDeduction.h b/include/clang/Sema/TemplateDeduction.h
index 3abb8f1889..8292045fdb 100644
--- a/include/clang/Sema/TemplateDeduction.h
+++ b/include/clang/Sema/TemplateDeduction.h
@@ -157,8 +157,8 @@ public:
   /// \brief The expression which caused a deduction failure.
   ///
   ///   TDK_FailedOverloadResolution: this argument is the reference to
-  //    an overloaded function which could not be resolved to a specific
-  //    function.
+  ///   an overloaded function which could not be resolved to a specific
+  ///   function.
   Expr *Expression;
 };