From 43b5b485a203f190ee4d5d3cab19c44ca865d316 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Mon, 30 Nov 2020 15:43:48 -0800
Subject: [PATCH] Fix GCC 5.3 compile error in ASTImporter code

Try to simplify this code a different way: use less Expected, more
outparams.
---
 clang/lib/AST/ASTImporter.cpp | 62 +++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 35 deletions(-)

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 1b01431..7a1415b 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -202,6 +202,9 @@ namespace clang {
       return *MaybeVal;
     }
 
+    ExplicitSpecifier importExplicitSpecifier(Error &Err,
+                                              ExplicitSpecifier ESpec);
+
     // Wrapper for an overload set.
     template <typename ToDeclT> struct CallOverloadedCreateFun {
       template <typename... Args> decltype(auto) operator()(Args &&... args) {
@@ -3153,6 +3156,14 @@ bool ASTNodeImporter::hasAutoReturnTypeDeclaredInside(FunctionDecl *D) {
   return false;
 }
 
+ExplicitSpecifier
+ASTNodeImporter::importExplicitSpecifier(Error &Err, ExplicitSpecifier ESpec) {
+  Expr *ExplicitExpr = ESpec.getExpr();
+  if (ExplicitExpr)
+    ExplicitExpr = importChecked(Err, ESpec.getExpr());
+  return ExplicitSpecifier(ExplicitExpr, ESpec.getKind());
+}
+
 ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
 
   SmallVector<Decl *, 2> Redecls = getCanonicalForwardRedeclChain(D);
@@ -3329,34 +3340,17 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
       return ToPOrErr.takeError();
   }
 
-  // Common code to import an explicit specifier of different kind of functions.
-  auto ImportExplicitExpr = [this, &Err](auto *Fun) -> ExpectedExpr {
-    Expr *ExplicitExpr = nullptr;
-    if (Fun->getExplicitSpecifier().getExpr()) {
-      ExplicitExpr = importChecked(Err, Fun->getExplicitSpecifier().getExpr());
-      if (Err)
-        return std::move(Err);
-    }
-    return ExplicitExpr;
-  };
-
   // Create the imported function.
   FunctionDecl *ToFunction = nullptr;
   if (auto *FromConstructor = dyn_cast<CXXConstructorDecl>(D)) {
-    Expr *ExplicitExpr = nullptr;
-    if (FromConstructor->getExplicitSpecifier().getExpr()) {
-      auto Imp = import(FromConstructor->getExplicitSpecifier().getExpr());
-      if (!Imp)
-        return Imp.takeError();
-      ExplicitExpr = *Imp;
-    }
+    ExplicitSpecifier ESpec =
+        importExplicitSpecifier(Err, FromConstructor->getExplicitSpecifier());
+    if (Err)
+      return std::move(Err);
     if (GetImportedOrCreateDecl<CXXConstructorDecl>(
             ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
-            ToInnerLocStart, NameInfo, T, TInfo,
-            ExplicitSpecifier(
-                ExplicitExpr,
-                FromConstructor->getExplicitSpecifier().getKind()),
-            D->isInlineSpecified(), D->isImplicit(), D->getConstexprKind(),
+            ToInnerLocStart, NameInfo, T, TInfo, ESpec, D->isInlineSpecified(),
+            D->isImplicit(), D->getConstexprKind(),
             InheritedConstructor(), // FIXME: Properly import inherited
                                     // constructor info
             TrailingRequiresClause))
@@ -3381,14 +3375,13 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
     ToDtor->setOperatorDelete(ToOperatorDelete, ToThisArg);
   } else if (CXXConversionDecl *FromConversion =
                  dyn_cast<CXXConversionDecl>(D)) {
-    ExpectedExpr ExplicitExpr = ImportExplicitExpr(FromConversion);
-    if (!ExplicitExpr)
-      return ExplicitExpr.takeError();
+    ExplicitSpecifier ESpec =
+        importExplicitSpecifier(Err, FromConversion->getExplicitSpecifier());
+    if (Err)
+      return std::move(Err);
     if (GetImportedOrCreateDecl<CXXConversionDecl>(
             ToFunction, D, Importer.getToContext(), cast<CXXRecordDecl>(DC),
-            ToInnerLocStart, NameInfo, T, TInfo, D->isInlineSpecified(),
-            ExplicitSpecifier(*ExplicitExpr,
-                              FromConversion->getExplicitSpecifier().getKind()),
+            ToInnerLocStart, NameInfo, T, TInfo, D->isInlineSpecified(), ESpec,
             D->getConstexprKind(), SourceLocation(), TrailingRequiresClause))
       return ToFunction;
   } else if (auto *Method = dyn_cast<CXXMethodDecl>(D)) {
@@ -3399,13 +3392,12 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
             SourceLocation(), TrailingRequiresClause))
       return ToFunction;
   } else if (auto *Guide = dyn_cast<CXXDeductionGuideDecl>(D)) {
-    ExpectedExpr ExplicitExpr = ImportExplicitExpr(Guide);
-    if (!ExplicitExpr)
-      return ExplicitExpr.takeError();
+    ExplicitSpecifier ESpec =
+        importExplicitSpecifier(Err, Guide->getExplicitSpecifier());
+    if (Err)
+      return std::move(Err);
     if (GetImportedOrCreateDecl<CXXDeductionGuideDecl>(
-            ToFunction, D, Importer.getToContext(), DC, ToInnerLocStart,
-            ExplicitSpecifier(*ExplicitExpr,
-                              Guide->getExplicitSpecifier().getKind()),
+            ToFunction, D, Importer.getToContext(), DC, ToInnerLocStart, ESpec,
             NameInfo, T, TInfo, ToEndLoc))
       return ToFunction;
     cast<CXXDeductionGuideDecl>(ToFunction)
-- 
2.7.4