From 2e3ed4a852d07ef2d329fbb391a8d1c5bec337d2 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Fri, 16 Aug 2019 19:53:22 +0000
Subject: [PATCH] Stop abusing SuppressAllDiagnostics when speculatively
 determining whether an expression would be valid during error recovery.

llvm-svn: 369145
---
 clang/lib/Parse/ParseExpr.cpp |  6 +++---
 clang/lib/Sema/Sema.cpp       |  4 +---
 clang/lib/Sema/SemaOpenMP.cpp | 22 +++++++++++-----------
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 05458fe..43b87b9 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1772,12 +1772,12 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
             OpKind == tok::arrow ? tok::period : tok::arrow;
         ExprResult CorrectedLHS(/*Invalid=*/true);
         if (getLangOpts().CPlusPlus && OrigLHS) {
-          const bool DiagsAreSuppressed = Diags.getSuppressAllDiagnostics();
-          Diags.setSuppressAllDiagnostics(true);
+          // FIXME: Creating a TentativeAnalysisScope from outside Sema is a
+          // hack.
+          Sema::TentativeAnalysisScope Trap(Actions);
           CorrectedLHS = Actions.ActOnStartCXXMemberReference(
               getCurScope(), OrigLHS, OpLoc, CorrectedOpKind, ObjectType,
               MayBePseudoDestructor);
-          Diags.setSuppressAllDiagnostics(DiagsAreSuppressed);
         }
 
         Expr *Base = LHS.get();
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index e8bad88..89e7d4c9 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -1929,11 +1929,9 @@ bool Sema::tryExprAsCall(Expr &E, QualType &ZeroArgCallReturnTy,
   // member templates with defaults/deduction of template arguments, overloads
   // with default arguments, etc.
   if (IsMemExpr && !E.isTypeDependent()) {
-    bool Suppress = getDiagnostics().getSuppressAllDiagnostics();
-    getDiagnostics().setSuppressAllDiagnostics(true);
+    Sema::TentativeAnalysisScope Trap(*this);
     ExprResult R = BuildCallToMemberFunction(nullptr, &E, SourceLocation(),
                                              None, SourceLocation());
-    getDiagnostics().setSuppressAllDiagnostics(Suppress);
     if (R.isUsable()) {
       ZeroArgCallReturnTy = R.get()->getType();
       return true;
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 4f0e20b..79d9561 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -5798,8 +5798,7 @@ Expr *OpenMPIterationSpaceChecker::buildPreCond(
     Scope *S, Expr *Cond,
     llvm::MapVector<const Expr *, DeclRefExpr *> &Captures) const {
   // Try to build LB <op> UB, where <op> is <, >, <=, or >=.
-  bool Suppress = SemaRef.getDiagnostics().getSuppressAllDiagnostics();
-  SemaRef.getDiagnostics().setSuppressAllDiagnostics(/*Val=*/true);
+  Sema::TentativeAnalysisScope Trap(SemaRef);
 
   ExprResult NewLB =
       InitDependOnLC ? LB : tryBuildCapture(SemaRef, LB, Captures);
@@ -5821,7 +5820,7 @@ Expr *OpenMPIterationSpaceChecker::buildPreCond(
           CondExpr.get(), SemaRef.Context.BoolTy, /*Action=*/Sema::AA_Casting,
           /*AllowExplicit=*/true);
   }
-  SemaRef.getDiagnostics().setSuppressAllDiagnostics(Suppress);
+
   // Otherwise use original loop condition and evaluate it in runtime.
   return CondExpr.isUsable() ? CondExpr.get() : Cond;
 }
@@ -6243,8 +6242,8 @@ static ExprResult buildCounterUpdate(
   if (VarRef.get()->getType()->isOverloadableType() ||
       NewStart.get()->getType()->isOverloadableType() ||
       Update.get()->getType()->isOverloadableType()) {
-    bool Suppress = SemaRef.getDiagnostics().getSuppressAllDiagnostics();
-    SemaRef.getDiagnostics().setSuppressAllDiagnostics(/*Val=*/true);
+    Sema::TentativeAnalysisScope Trap(SemaRef);
+
     Update =
         SemaRef.BuildBinOp(S, Loc, BO_Assign, VarRef.get(), NewStart.get());
     if (Update.isUsable()) {
@@ -6256,7 +6255,6 @@ static ExprResult buildCounterUpdate(
                                             UpdateVal.get());
       }
     }
-    SemaRef.getDiagnostics().setSuppressAllDiagnostics(Suppress);
   }
 
   // Second attempt: try to build 'VarRef = Start (+|-) Iter * Step'.
@@ -13605,11 +13603,13 @@ Sema::ActOnOpenMPDependClause(OpenMPDependClauseKind DepKind,
             << RefExpr->getSourceRange();
         continue;
       }
-      bool Suppress = getDiagnostics().getSuppressAllDiagnostics();
-      getDiagnostics().setSuppressAllDiagnostics(/*Val=*/true);
-      ExprResult Res =
-          CreateBuiltinUnaryOp(ELoc, UO_AddrOf, RefExpr->IgnoreParenImpCasts());
-      getDiagnostics().setSuppressAllDiagnostics(Suppress);
+
+      ExprResult Res;
+      {
+        Sema::TentativeAnalysisScope Trap(*this);
+        Res = CreateBuiltinUnaryOp(ELoc, UO_AddrOf,
+                                   RefExpr->IgnoreParenImpCasts());
+      }
       if (!Res.isUsable() && !isa<OMPArraySectionExpr>(SimpleExpr)) {
         Diag(ELoc, diag::err_omp_expected_addressable_lvalue_or_array_item)
             << RefExpr->getSourceRange();
-- 
2.7.4