[PATCH] Handle errors in lambda prototype instantiation correctly

[Richard Smith]

LGTM
On 15 Dec 2014 11:28, "Reid Kleckner" <rnk at google.com> wrote:

> Hi rsmith,
>
> Previously we would attempt to build a TypeSourceInfo for a null type,
> and then we would forget to pop the function scope before returning an
> error.
>
> http://reviews.llvm.org/D6665
>
> Files:
>   include/clang/Sema/Sema.h
>   lib/Sema/TreeTransform.h
>   test/SemaCXX/lambda-expressions.cpp
>
> Index: include/clang/Sema/Sema.h
> ===================================================================
> --- include/clang/Sema/Sema.h
> +++ include/clang/Sema/Sema.h
> @@ -3101,6 +3101,18 @@
>      Sema &S;
>    };
>
> +  /// An RAII helper that pops function a function scope on exit.
> +  struct FunctionScopeRAII {
> +    Sema &S;
> +    bool Active;
> +    FunctionScopeRAII(Sema &S) : Active(true), S(S) {}
> +    ~FunctionScopeRAII() {
> +      if (Active)
> +        S.PopFunctionScopeInfo();
> +    }
> +    void disable() { Active = false; }
> +  };
> +
>    StmtResult ActOnDeclStmt(DeclGroupPtrTy Decl,
>                                     SourceLocation StartLoc,
>                                     SourceLocation EndLoc);
> Index: lib/Sema/TreeTransform.h
> ===================================================================
> --- lib/Sema/TreeTransform.h
> +++ lib/Sema/TreeTransform.h
> @@ -9121,6 +9121,8 @@
>    }
>
>    LambdaScopeInfo *LSI = getSema().PushLambdaScope();
> +  Sema::FunctionScopeRAII FuncScopeCleanup(getSema());
> +
>    // Transform the template parameters, and add them to the current
>    // instantiation scope. The null case is handled correctly.
>    LSI->GLTemplateParameterList =
> getDerived().TransformTemplateParameterList(
> @@ -9145,10 +9147,10 @@
>            return
> This->TransformExceptionSpec(OldCallOpFPTL.getBeginLoc(), ESI,
>                                                ExceptionStorage, Changed);
>          });
> +    if (NewCallOpType.isNull())
> +      return ExprError();
>      NewCallOpTSI = NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context,
>                                                          NewCallOpType);
> -    if (!NewCallOpTSI)
> -      return ExprError();
>    }
>
>    // Create the local class that will describe the lambda.
> @@ -9168,6 +9170,10 @@
>
>    getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
>
> +  // TransformLambdaScope will manage the function scope, so we can
> disable the
> +  // cleanup.
> +  FuncScopeCleanup.disable();
> +
>    return getDerived().TransformLambdaScope(E, NewCallOperator,
>        InitCaptureExprsAndTypes);
>  }
> Index: test/SemaCXX/lambda-expressions.cpp
> ===================================================================
> --- test/SemaCXX/lambda-expressions.cpp
> +++ test/SemaCXX/lambda-expressions.cpp
> @@ -425,3 +425,17 @@
>    }
>    template void g<int>();
>  }
> +
> +namespace error_in_transform_prototype {
> +  template<class T>
> +  void f(T t) {
> +    // expected-error at +2 {{type 'int' cannot be used prior to '::'
> because it has no members}}
> +    // expected-error at +1 {{no member named 'ns' in
> 'error_in_transform_prototype::S'}}
> +    auto x = [](typename T::ns::type &k) {};
> +  }
> +  class S {};
> +  void foo() {
> +    f(5); // expected-note {{requested here}}
> +    f(S()); // expected-note {{requested here}}
> +  }
> +}
>
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