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Squelch MSVC warning exporting subclasses of runtime_error (fix for PR #1433) #1470

Merged
merged 3 commits into from
Dec 13, 2019
Merged

Squelch MSVC warning exporting subclasses of runtime_error (fix for PR #1433) #1470

merged 3 commits into from
Dec 13, 2019

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iPherian
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@iPherian iPherian commented Dec 10, 2019 •
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Based on PR #1433, which was reverted because of issue #1450 (i.e. fails to build under VS2015). This PR fixes that build while keeping the applicable warnings silenced.

VS2015 does not support the __pragma(...) syntax in the midst of a class declaration, so move it to just before the declaration.

original explanation:

When compiling {fmt} as a DLL, MSVC complains that we are exporting classes that inherit from "std::runtime_error", which we are not exporting.

In this case, it's not really a problem because that symbol is already exported via the C++ stdlib. So we just add a pragma to silence the warning.

Successful build log:

Log 
cmake -G "Visual Studio 14 2015" -Ax64 -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=ON ..
-- CMake version: 3.15.5
-- The CXX compiler identification is MSVC 19.0.24241.7
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Version: 6.1.1
-- Build type: Release
-- CXX_STANDARD: 11
-- Performing Test has_std_11_flag
-- Performing Test has_std_11_flag - Success
-- Performing Test has_std_0x_flag
-- Performing Test has_std_0x_flag - Failed
-- Performing Test SUPPORTS_VARIADIC_TEMPLATES
-- Performing Test SUPPORTS_VARIADIC_TEMPLATES - Success
-- Performing Test SUPPORTS_USER_DEFINED_LITERALS
-- Performing Test SUPPORTS_USER_DEFINED_LITERALS - Success
-- Performing Test FMT_HAS_VARIANT
-- Performing Test FMT_HAS_VARIANT - Failed
-- Looking for _strtod_l
-- Looking for _strtod_l - found
-- Target 'doc' disabled (requires doxygen)
-- Looking for C++ include pthread.h
-- Looking for C++ include pthread.h - not found
-- Found Threads: TRUE  
-- Performing Test HAVE_FNO_DELETE_NULL_POINTER_CHECKS
-- Performing Test HAVE_FNO_DELETE_NULL_POINTER_CHECKS - Failed
-- FMT_PEDANTIC: OFF
-- Configuring done
-- Generating done
-- Build files have been written to: C:/projects/fmt/build
cmake --build . --config Release
Microsoft (R) Build Engine version 14.0.25420.1
Copyright (C) Microsoft Corporation. All rights reserved.
  Checking Build System
  Building Custom Rule C:/projects/fmt/CMakeLists.txt
  format.cc
  posix.cc
  Generating Code...
     Creating library C:/projects/fmt/build/Release/fmt.lib and object C:/projects/fmt/build/Release/fmt.exp
  fmt.vcxproj -> C:\projects\fmt\build\bin\Release\fmt.dll
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  gmock-gtest-all.cc
  gmock.vcxproj -> C:\projects\fmt\build\test\Release\gmock.lib
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  test-main.cc
  gtest-extra.cc
  util.cc
  Generating Code...
  test-main.vcxproj -> C:\projects\fmt\build\test\Release\test-main.lib
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  assert-test.cc
C:\projects\fmt\test\assert-test.cc(21): warning C4003: not enough actual parameters for macro 'GTEST_SUPPRESS_UNREACHABLE_CODE_WARNING_BELOW_' [C:\projects\fmt\build\test\assert-test.vcxproj]
  assert-test.vcxproj -> C:\projects\fmt\build\bin\Release\assert-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  chrono-test.cc
  chrono-test.vcxproj -> C:\projects\fmt\build\bin\Release\chrono-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  color-test.cc
  color-test.vcxproj -> C:\projects\fmt\build\bin\Release\color-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  compile-test.cc
  compile-test.vcxproj -> C:\projects\fmt\build\bin\Release\compile-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  core-test.cc
  core-test.vcxproj -> C:\projects\fmt\build\bin\Release\core-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  custom-formatter-test.cc
  custom-formatter-test.vcxproj -> C:\projects\fmt\build\bin\Release\custom-formatter-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  format-test.cc
  format-test.vcxproj -> C:\projects\fmt\build\bin\Release\format-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  grisu-test.cc
  grisu-test.vcxproj -> C:\projects\fmt\build\bin\Release\grisu-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  gtest-extra-test.cc
  gtest-extra-test.vcxproj -> C:\projects\fmt\build\bin\Release\gtest-extra-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  header-only-test.cc
  header-only-test2.cc
  test-main.cc
  Generating Code...
  header-only-test.vcxproj -> C:\projects\fmt\build\bin\Release\header-only-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  locale-test.cc
  locale-test.vcxproj -> C:\projects\fmt\build\bin\Release\locale-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  ostream-test.cc
  ostream-test.vcxproj -> C:\projects\fmt\build\bin\Release\ostream-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  posix-mock-test.cc
  format.cc
  test-main.cc
  gtest-extra.cc
  util.cc
  Generating Code...
     Creating library C:/projects/fmt/build/test/Release/posix-mock-test.lib and object C:/projects/fmt/build/test/Release/posix-mock-test.exp
  posix-mock-test.vcxproj -> C:\projects\fmt\build\bin\Release\posix-mock-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  posix-test.cc
  posix-test.vcxproj -> C:\projects\fmt\build\bin\Release\posix-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  printf-test.cc
  printf-test.vcxproj -> C:\projects\fmt\build\bin\Release\printf-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  ranges-test.cc
  ranges-test.vcxproj -> C:\projects\fmt\build\bin\Release\ranges-test.exe
  Building Custom Rule C:/projects/fmt/test/CMakeLists.txt
  scan-test.cc
  scan-test.vcxproj -> C:\projects\fmt\build\bin\Release\scan-test.exe
  Building Custom Rule C:/projects/fmt/CMakeLists.txt
Discovering tests...OK
Build success

(build is of shared libraries under VS2015 i.e the config of the associated issue -- including because it's not currently on the auto tests for the repo)

P.S. I'm not sure if I should have cherry-picked, but the commits this one depends on were reverted.

I agree that my contributions are licensed under the {fmt} license, and agree to future changes to the licensing.

Chris Martin and others added 3 commits December 10, 2019 02:09
@iPherian
Squelch MSVC warning exporting subclasses of runtime_error
a118c65 
When compiling {fmt} as a DLL, MSVC complains that we are exporting
classes that inherit from "std::runtime_error", which we are not
exporting.

In this case, it's not really a problem because that symbol is already
exported via the C++ stdlib. So we just add a pragma to silence the
warning.
@bbolli @iPherian
Fix compilation with MinGW
6d2491b 
Commit 3bc28fc ("Squelch MSVC warning exporting subclasses of
runtime_error", 2019-11-29) silenced a MSVC warning under. The MinGW
compiler also defines _WIN32, but does not support the "warning" pragma.

Introduce a helper macro to squelch the MSVC warning only when using the
Microsoft compiler.

Signed-off-by: Beat Bolli <dev@drbeat.li>
@iPherian
Fix compilation with VS2015 (fmtlib#1450)
2a10d75 
VS2015 does not support the __pragma(...) syntax in the midst of a
class declaration, so move it to just before the declaration.
vitaut
vitaut reviewed Dec 13, 2019
View reviewed changes
include/fmt/format.h
Comment on lines +691 to 692
FMT_CLASS_API
class FMT_API format_error : public std::runtime_error {
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Can we define FMT_CLASS_API to include FMT_API and simplify this as follows:

class FMT_CLASS_API format_error : public std::runtime_error {

?

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Nevermind, re-reading the PR description I realized that it's not possible.

@vitaut vitaut merged commit 8ab1c5c into fmtlib:master Dec 13, 2019
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vitaut commented Dec 13, 2019

Merged, thanks!

@iPherian iPherian deleted the fix_suppress_export_warnings branch December 14, 2019 07:37
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@iPherian @vitaut @bbolli