From ce6b78128f7fde3b26b6cf66adc6c982cde90bb8 Mon Sep 17 00:00:00 2001
From: Gabor Marton <martongabesz@gmail.com>
Date: Wed, 8 May 2019 15:23:48 +0000
Subject: [PATCH] [ASTImporter] Fix inequivalence of unresolved exception spec

Summary:
Structural equivalence of methods can falsely report false when the
exception specifier is unresolved (i.e unevaluated or not instantiated).

(This caused one assertion during bitcoin ctu-analysis.)

Reviewers: a_sidorin, shafik, a.sidorin

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D61424

llvm-svn: 360261
---
 clang/lib/AST/ASTImporter.cpp              |  5 ++++
 clang/lib/AST/ASTStructuralEquivalence.cpp | 48 +++++++++++++++++++-----------
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index da0d689..7ce2abe 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3130,6 +3130,11 @@ ExpectedDecl ASTNodeImporter::VisitFunctionDecl(FunctionDecl *D) {
     auto *Recent = const_cast<FunctionDecl *>(
           FoundByLookup->getMostRecentDecl());
     ToFunction->setPreviousDecl(Recent);
+    // FIXME Probably we should merge exception specifications.  E.g. In the
+    // "To" context the existing function may have exception specification with
+    // noexcept-unevaluated, while the newly imported function may have an
+    // evaluated noexcept.  A call to adjustExceptionSpec() on the imported
+    // decl and its redeclarations may be required.
   }
 
   // Import Ctor initializers.
diff --git a/clang/lib/AST/ASTStructuralEquivalence.cpp b/clang/lib/AST/ASTStructuralEquivalence.cpp
index 567945c..bf084e3 100644
--- a/clang/lib/AST/ASTStructuralEquivalence.cpp
+++ b/clang/lib/AST/ASTStructuralEquivalence.cpp
@@ -322,6 +322,36 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
   return true;
 }
 
+/// Check the equivalence of exception specifications.
+static bool IsEquivalentExceptionSpec(StructuralEquivalenceContext &Context,
+                                      const FunctionProtoType *Proto1,
+                                      const FunctionProtoType *Proto2) {
+
+  auto Spec1 = Proto1->getExceptionSpecType();
+  auto Spec2 = Proto2->getExceptionSpecType();
+
+  if (isUnresolvedExceptionSpec(Spec1) || isUnresolvedExceptionSpec(Spec2))
+    return true;
+
+  if (Spec1 != Spec2)
+    return false;
+  if (Spec1 == EST_Dynamic) {
+    if (Proto1->getNumExceptions() != Proto2->getNumExceptions())
+      return false;
+    for (unsigned I = 0, N = Proto1->getNumExceptions(); I != N; ++I) {
+      if (!IsStructurallyEquivalent(Context, Proto1->getExceptionType(I),
+                                    Proto2->getExceptionType(I)))
+        return false;
+    }
+  } else if (isComputedNoexcept(Spec1)) {
+    if (!IsStructurallyEquivalent(Context, Proto1->getNoexceptExpr(),
+                                  Proto2->getNoexceptExpr()))
+      return false;
+  }
+
+  return true;
+}
+
 /// Determine structural equivalence of two types.
 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
                                      QualType T1, QualType T2) {
@@ -536,24 +566,8 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
         cast<FunctionProtoType>(OrigT1.getDesugaredType(Context.FromCtx));
     const auto *OrigProto2 =
         cast<FunctionProtoType>(OrigT2.getDesugaredType(Context.ToCtx));
-    auto Spec1 = OrigProto1->getExceptionSpecType();
-    auto Spec2 = OrigProto2->getExceptionSpecType();
-
-    if (Spec1 != Spec2)
+    if (!IsEquivalentExceptionSpec(Context, OrigProto1, OrigProto2))
       return false;
-    if (Spec1 == EST_Dynamic) {
-      if (OrigProto1->getNumExceptions() != OrigProto2->getNumExceptions())
-        return false;
-      for (unsigned I = 0, N = OrigProto1->getNumExceptions(); I != N; ++I) {
-        if (!IsStructurallyEquivalent(Context, OrigProto1->getExceptionType(I),
-                                      OrigProto2->getExceptionType(I)))
-          return false;
-      }
-    } else if (isComputedNoexcept(Spec1)) {
-      if (!IsStructurallyEquivalent(Context, OrigProto1->getNoexceptExpr(),
-                                    OrigProto2->getNoexceptExpr()))
-        return false;
-    }
 
     // Fall through to check the bits common with FunctionNoProtoType.
     LLVM_FALLTHROUGH;
-- 
2.7.4