From a0f32072cd808c09524e8d469d3f7d4f866329c4 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Sat, 18 Feb 2017 01:01:48 +0000
Subject: [PATCH] Handle deduction guides better in -ast-print.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@295521 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/DeclPrinter.cpp          | 15 ++++++++++++---
 test/Misc/ast-dump-templates.cpp | 10 ++++++++--
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/lib/AST/DeclPrinter.cpp b/lib/AST/DeclPrinter.cpp
index 15b9a6de0b..aedc35b0f8 100644
--- a/lib/AST/DeclPrinter.cpp
+++ b/lib/AST/DeclPrinter.cpp
@@ -481,6 +481,7 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
 
   CXXConstructorDecl *CDecl = dyn_cast<CXXConstructorDecl>(D);
   CXXConversionDecl *ConversionDecl = dyn_cast<CXXConversionDecl>(D);
+  CXXDeductionGuideDecl *GuideDecl = dyn_cast<CXXDeductionGuideDecl>(D);
   if (!Policy.SuppressSpecifiers) {
     switch (D->getStorageClass()) {
     case SC_None: break;
@@ -496,13 +497,16 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
     if (D->isModulePrivate())    Out << "__module_private__ ";
     if (D->isConstexpr() && !D->isExplicitlyDefaulted()) Out << "constexpr ";
     if ((CDecl && CDecl->isExplicitSpecified()) ||
-        (ConversionDecl && ConversionDecl->isExplicit()))
+        (ConversionDecl && ConversionDecl->isExplicitSpecified()) ||
+        (GuideDecl && GuideDecl->isExplicitSpecified()))
       Out << "explicit ";
   }
 
   PrintingPolicy SubPolicy(Policy);
   SubPolicy.SuppressSpecifiers = false;
   std::string Proto = D->getNameInfo().getAsString();
+  if (GuideDecl)
+    Proto = GuideDecl->getDeducedTemplate()->getDeclName().getAsString();
   if (const TemplateArgumentList *TArgs = D->getTemplateSpecializationArgs()) {
     llvm::raw_string_ostream POut(Proto);
     DeclPrinter TArgPrinter(POut, SubPolicy, Indentation);
@@ -652,7 +656,9 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
       }
     } else if (!ConversionDecl && !isa<CXXDestructorDecl>(D)) {
       if (FT && FT->hasTrailingReturn()) {
-        Out << "auto " << Proto << " -> ";
+        if (!GuideDecl)
+          Out << "auto ";
+        Out << Proto << " -> ";
         Proto.clear();
       }
       AFT->getReturnType().print(Out, Policy, Proto);
@@ -1044,7 +1050,10 @@ void DeclPrinter::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
   prettyPrintPragmas(D->getTemplatedDecl());
   VisitRedeclarableTemplateDecl(D);
 
-  if (PrintInstantiation) {
+  // Never print "instantiations" for deduction guides (they don't really
+  // have them).
+  if (PrintInstantiation &&
+      !isa<CXXDeductionGuideDecl>(D->getTemplatedDecl())) {
     FunctionDecl *PrevDecl = D->getTemplatedDecl();
     const FunctionDecl *Def;
     if (PrevDecl->isDefined(Def) && Def != PrevDecl)
diff --git a/test/Misc/ast-dump-templates.cpp b/test/Misc/ast-dump-templates.cpp
index eb493b4277..89feee7526 100644
--- a/test/Misc/ast-dump-templates.cpp
+++ b/test/Misc/ast-dump-templates.cpp
@@ -1,7 +1,7 @@
-// RUN: %clang_cc1 -ast-print %s > %t
+// RUN: %clang_cc1 -std=c++1z -ast-print %s > %t
 // RUN: FileCheck < %t %s -check-prefix=CHECK1
 // RUN: FileCheck < %t %s -check-prefix=CHECK2
-// RUN: %clang_cc1 -ast-dump %s | FileCheck --check-prefix=DUMP %s
+// RUN: %clang_cc1 -std=c++1z -ast-dump %s | FileCheck --check-prefix=DUMP %s
 
 template <int X, typename Y, int Z = 5>
 struct foo {
@@ -61,3 +61,9 @@ void tmpl() {
 
 // DUMP: UnresolvedLookupExpr {{.*}} <col:3> '<overloaded function type>' lvalue (ADL) = 'func'
 }
+
+namespace test3 {
+  template<typename T> struct A {};
+  template<typename T> A(T) -> A<int>;
+  // CHECK1: template <typename T> A(T) -> A<int>;
+}
-- 
2.40.0