[llvm] r339802 - [Support] Add a basic C API for llvm::Error.

Adrian Prantl via llvm-commits llvm-commits at lists.llvm.org
Thu Aug 16 13:41:37 PDT 2018


I'm stumped, too. it looks like I can't reproduce the warning any longer... The module map for the C api is just

  module LLVM_C {
    umbrella "."
    module * { export * }
  }

so I don't know how that could lead to the error below.

Oh well. Thanks for looking at it anyway,
adrian

> On Aug 16, 2018, at 11:31 AM, Lang Hames <lhames at gmail.com> wrote:
> 
> Hi Adrian,
> 
> That seems odd. Do you know why this would be happening for llvm-c/Error.h and not other llvm-c headers?
> 
> Cheers,
> Lang.
> 
> On Wed, Aug 15, 2018 at 1:53 PM Adrian Prantl <aprantl at apple.com> wrote:
> It looks like you may also need to update the module.modulemap for building with -DLLVM_ENABLE_MODULES=On:
> 
> While building module 'LLVM_Utils' imported from ../lib/Support/APSInt.cpp:15:
> In file included from <module-includes>:77:
> In file included from ../include/llvm/Support/BinaryStreamError.h:14:
> ../include/llvm/Support/Error.h:17:2: warning: missing submodule 'LLVM_C.Error' [-Wincomplete-umbrella]
> #include "llvm-c/Error.h"
>  ^       ~~~~~~~~~~~~~~~~
> 1 warning generated.
> 
> thanks,
> adrian
> 
>> On Aug 15, 2018, at 11:42 AM, Lang Hames via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>> 
>> Author: lhames
>> Date: Wed Aug 15 11:42:11 2018
>> New Revision: 339802
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=339802&view=rev
>> Log:
>> [Support] Add a basic C API for llvm::Error.
>> 
>> Summary:
>> The C-API supports consuming errors, converting an error to a string error
>> message, and querying an error's type. Other LLVM C APIs that wish to use
>> llvm::Error can supply error-type-id checkers and custom
>> error-to-structured-type converters for any custom errors they provide.
>> 
>> Reviewers: bogner, zturner, labath, dblaikie
>> 
>> Subscribers: llvm-commits
>> 
>> Differential Revision: https://reviews.llvm.org/D50716
>> 
>> Added:
>>    llvm/trunk/include/llvm-c/Error.h
>> Modified:
>>    llvm/trunk/include/llvm/Support/Error.h
>>    llvm/trunk/lib/Support/Error.cpp
>>    llvm/trunk/unittests/Support/ErrorTest.cpp
>> 
>> Added: llvm/trunk/include/llvm-c/Error.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm-c/Error.h?rev=339802&view=auto
>> ==============================================================================
>> --- llvm/trunk/include/llvm-c/Error.h (added)
>> +++ llvm/trunk/include/llvm-c/Error.h Wed Aug 15 11:42:11 2018
>> @@ -0,0 +1,65 @@
>> +/*===------- llvm-c/Error.h - llvm::Error class C Interface -------*- C -*-===*\
>> +|*                                                                            *|
>> +|*                     The LLVM Compiler Infrastructure                       *|
>> +|*                                                                            *|
>> +|* This file is distributed under the University of Illinois Open Source      *|
>> +|* License. See LICENSE.TXT for details.                                      *|
>> +|*                                                                            *|
>> +|*===----------------------------------------------------------------------===*|
>> +|*                                                                            *|
>> +|* This file defines the C interface to LLVM's Error class.                   *|
>> +|*                                                                            *|
>> +\*===----------------------------------------------------------------------===*/
>> +
>> +#ifndef LLVM_C_ERROR_H
>> +#define LLVM_C_ERROR_H
>> +
>> +#ifdef __cplusplus
>> +extern "C" {
>> +#endif
>> +
>> +/**
>> + * Opaque reference to an error instance. Null serves as the 'success' value.
>> + */
>> +typedef struct LLVMOpaqueError *LLVMErrorRef;
>> +
>> +/**
>> + * Error type identifier.
>> + */
>> +typedef const void *LLVMErrorTypeId;
>> +
>> +/**
>> + * Returns the type id for the given error instance, which must be a failure
>> + * value (i.e. non-null).
>> + */
>> +LLVMErrorTypeId LLVMGetErrorTypeId(LLVMErrorRef Err);
>> +
>> +/**
>> + * Dispose of the given error without handling it. This operation consumes the
>> + * error, and the given LLVMErrorRef value is not usable once this call returns.
>> + * Note: This method *only* needs to be called if the error is not being passed
>> + * to some other consuming operation, e.g. LLVMGetErrorMessage.
>> + */
>> +void LLVMConsumeError(LLVMErrorRef Err);
>> +
>> +/**
>> + * Returns the given string's error message. This operation consumes the error,
>> + * and the given LLVMErrorRef value is not usable once this call returns.
>> + */
>> +char *LLVMGetErrorMessage(LLVMErrorRef Err);
>> +
>> +/**
>> + * Dispose of the given error message.
>> + */
>> +void LLVMDisposeErrorMessage(char *ErrMsg);
>> +
>> +/**
>> + * Returns the type id for llvm StringError.
>> + */
>> +LLVMErrorTypeId LLVMGetStringErrorTypeId();
>> +
>> +#ifdef __cplusplus
>> +}
>> +#endif
>> +
>> +#endif
>> 
>> Modified: llvm/trunk/include/llvm/Support/Error.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Error.h?rev=339802&r1=339801&r2=339802&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Support/Error.h (original)
>> +++ llvm/trunk/include/llvm/Support/Error.h Wed Aug 15 11:42:11 2018
>> @@ -14,8 +14,9 @@
>> #ifndef LLVM_SUPPORT_ERROR_H
>> #define LLVM_SUPPORT_ERROR_H
>> 
>> -#include "llvm/ADT/SmallVector.h"
>> +#include "llvm-c/Error.h"
>> #include "llvm/ADT/STLExtras.h"
>> +#include "llvm/ADT/SmallVector.h"
>> #include "llvm/ADT/StringExtras.h"
>> #include "llvm/ADT/Twine.h"
>> #include "llvm/Config/abi-breaking.h"
>> @@ -167,6 +168,9 @@ class LLVM_NODISCARD Error {
>>   // error.
>>   template <typename T> friend class Expected;
>> 
>> +  // wrap needs to be able to steal the payload.
>> +  friend LLVMErrorRef wrap(Error);
>> +
>> protected:
>>   /// Create a success value. Prefer using 'Error::success()' for readability
>>   Error() {
>> @@ -1183,6 +1187,17 @@ private:
>>   std::function<int(const Error &)> GetExitCode;
>> };
>> 
>> +/// Conversion from Error to LLVMErrorRef for C error bindings.
>> +inline LLVMErrorRef wrap(Error Err) {
>> +  return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
>> +}
>> +
>> +/// Conversion from LLVMErrorRef to Error for C error bindings.
>> +inline Error unwrap(LLVMErrorRef ErrRef) {
>> +  return Error(std::unique_ptr<ErrorInfoBase>(
>> +      reinterpret_cast<ErrorInfoBase *>(ErrRef)));
>> +}
>> +
>> } // end namespace llvm
>> 
>> #endif // LLVM_SUPPORT_ERROR_H
>> 
>> Modified: llvm/trunk/lib/Support/Error.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Error.cpp?rev=339802&r1=339801&r2=339802&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Support/Error.cpp (original)
>> +++ llvm/trunk/lib/Support/Error.cpp Wed Aug 15 11:42:11 2018
>> @@ -126,6 +126,26 @@ void report_fatal_error(Error Err, bool
>>   report_fatal_error(ErrMsg);
>> }
>> 
>> +} // end namespace llvm
>> +
>> +LLVMErrorTypeId LLVMGetErrorTypeId(LLVMErrorRef Err) {
>> +  return reinterpret_cast<ErrorInfoBase *>(Err)->dynamicClassID();
>> +}
>> +
>> +void LLVMConsumeError(LLVMErrorRef Err) { consumeError(unwrap(Err)); }
>> +
>> +char *LLVMGetErrorMessage(LLVMErrorRef Err) {
>> +  std::string Tmp = toString(unwrap(Err));
>> +  char *ErrMsg = new char[Tmp.size() + 1];
>> +  memcpy(ErrMsg, Tmp.data(), Tmp.size());
>> +  ErrMsg[Tmp.size()] = '\0';
>> +  return ErrMsg;
>> +}
>> +
>> +void LLVMDisposeErrorMessage(char *ErrMsg) { delete[] ErrMsg; }
>> +
>> +LLVMErrorTypeId LLVMGetStringErrorTypeId() {
>> +  return reinterpret_cast<void *>(&StringError::ID);
>> }
>> 
>> #ifndef _MSC_VER
>> 
>> Modified: llvm/trunk/unittests/Support/ErrorTest.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ErrorTest.cpp?rev=339802&r1=339801&r2=339802&view=diff
>> ==============================================================================
>> --- llvm/trunk/unittests/Support/ErrorTest.cpp (original)
>> +++ llvm/trunk/unittests/Support/ErrorTest.cpp Wed Aug 15 11:42:11 2018
>> @@ -8,6 +8,7 @@
>> //===----------------------------------------------------------------------===//
>> 
>> #include "llvm/Support/Error.h"
>> +#include "llvm-c/Error.h"
>> 
>> #include "llvm/ADT/Twine.h"
>> #include "llvm/Support/Errc.h"
>> @@ -832,4 +833,35 @@ TEST(Error, ErrorMatchers) {
>>       "  Actual: failed  (CustomError {0})");
>> }
>> 
>> +TEST(Error, C_API) {
>> +  EXPECT_THAT_ERROR(unwrap(wrap(Error::success())), Succeeded())
>> +      << "Failed to round-trip Error success value via C API";
>> +  EXPECT_THAT_ERROR(unwrap(wrap(make_error<CustomError>(0))),
>> +                    Failed<CustomError>())
>> +      << "Failed to round-trip Error failure value via C API";
>> +
>> +  auto Err =
>> +      wrap(make_error<StringError>("test message", inconvertibleErrorCode()));
>> +  EXPECT_EQ(LLVMGetErrorTypeId(Err), LLVMGetStringErrorTypeId())
>> +      << "Failed to match error type ids via C API";
>> +  char *ErrMsg = LLVMGetErrorMessage(Err);
>> +  EXPECT_STREQ(ErrMsg, "test message")
>> +      << "Failed to roundtrip StringError error message via C API";
>> +  LLVMDisposeErrorMessage(ErrMsg);
>> +
>> +  bool GotCSE = false;
>> +  bool GotCE = false;
>> +  handleAllErrors(
>> +    unwrap(wrap(joinErrors(make_error<CustomSubError>(42, 7),
>> +                           make_error<CustomError>(42)))),
>> +    [&](CustomSubError &CSE) {
>> +      GotCSE = true;
>> +    },
>> +    [&](CustomError &CE) {
>> +      GotCE = true;
>> +    });
>> +  EXPECT_TRUE(GotCSE) << "Failed to round-trip ErrorList via C API";
>> +  EXPECT_TRUE(GotCE) << "Failed to round-trip ErrorList via C API";
>> +}
>> +
>> } // end anon namespace
>> 
>> 
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