Discussions Issue archiveOCCT:Foundation Classes

Archived issue #0008239

Foundation Classes - directive "using namespace std" doesn't allow to build application with OCC and other 3rd party libraries

Open CASCADEOCCT:Foundation Classesclosed26 public notes

Description

If custom application uses the OCC and other 3rd party library (for example VTK
or Qt) based on ANSI streams then compiler fails during determination stream
symbols: istream, ostream, ... (compiler error C2872). Directive "using
namespace std" export the all symbol from std namespace into global scope.
Possible solution is not to use directive "using namespace std", but explicitly
specify STL stream symbols (std::ostream) and define preprocessor directive as
namespace prefix name for it.

Enclosed archive (Attachment 1 (TGZ)) contains example which illustrate proposed
solution with preprocessor directive OCC_STREAM_STD.

Do not hestitate to contact me.

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STV

Steps to reproduce

Not required

Public activity

26 archived notes

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01Commenter 12014-04-04 06:50

Currently we have a set of uses statements for a set of symbols from std namespace (mostly streams) in Standard_Stream.hxx. This can still cause incompatibilities, thus it might be reasonable to remove these, adding prefix std:: explicitly to all references to these symbols in OCCT code.

02Commenter 22019-07-26 10:33

Branch [archived branch] has been created by Participant.

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Detailed log of new commits:

Author: tiv
Date: Fri Jul 26 09:42:14 2019 +0300

03Commenter 22019-07-26 10:33

Branch [archived branch] has been created by Participant.

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Author: tiv
Date: Fri Jul 26 10:30:33 2019 +0300

    0008239: Foundation Classes - directive "using namespace std" doesn't allow to build application with OCC and other 3rd party libraries

    "using namespace" directives are removed from some places.
    Last entries of "using std::" are also removed.

04Commenter 22019-07-26 15:46

Branch [archived branch] has been updated by Participant.

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Author: tiv
Date: Fri Jul 26 15:35:06 2019 +0300

05Commenter 22019-07-26 15:46

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06Commenter 22019-07-26 16:35

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Author: tiv
Date: Fri Jul 26 16:29:19 2019 +0300

07Commenter 22019-07-26 16:36

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08Commenter 22019-07-26 17:06

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09Commenter 22019-07-26 17:06

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10Commenter 22019-07-26 17:39

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Author: tiv
Date: Fri Jul 26 17:34:43 2019 +0300

11Commenter 22019-07-26 17:39

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12Commenter 22019-07-26 21:51

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Author: tiv
Date: Fri Jul 26 18:42:27 2019 +0300

# std:: prefixes are added in the right places in samples.

13Commenter 22019-07-26 21:51

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14Commenter 22019-07-29 09:28

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15Commenter 22019-07-29 09:28

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16Commenter 22019-07-29 09:59

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17Commenter 22019-07-29 12:00

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Detailed log of new commits:

Author: tiv
Date: Mon Jul 29 11:58:08 2019 +0300

    0008239: Foundation Classes - directive "using namespace std" doesn't allow to build application with OCC and other 3rd party libraries

    "using namespace" directives are removed from some places.
    Last entries of "using std::" are also removed.
    "endl" manipulator for Message_Messenger is renamed to "Message_EndLine".

18Commenter 22019-08-02 10:35

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19Commenter 22019-08-02 10:36

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20Commenter 202019-08-02 16:20

Patch is ready for review: http://jenkins-test-12.nnov.opencascade.com:8080/view/CR8239-master-TIV/view/ALL/

Main OCCT branch: CR8239
OCCT branch with squashed commits: CR8239_1

Main branch in OCCT Products: CR8239
OCCT Products branch with squashed commits: CR8239_1

Some comments on this patch:

Most of the changes are related to the removing of the last entries of using std:: from the header file Standard_Stream.hxx. There were the following names of the standard library objects:

istream
ostream
ifstream
ofstream
fstream
filebuf
streambuf
streampos
ios
cout
cerr
cin
endl
ends
flush
setw
setprecision
hex
dec

The corresponding changes in other source files consist of adding std:: prefixes to these names. These changes were done mostly via the following and some other regular expressions:

dec, hex, ends, flush
Find what:

(?<prefix>\<\<[\n\r\s]*)(?<body>dec|hex|ends|flush)\b(?<postfix>[\n\r\s]*(\<\<|;))

Replace with:

${prefix}std::${body}

setw, setprecision
Find what:

(?<prefix>\<\<[\n\r\s]*)(?<body>setw|setprecision)(?<postfix>[\n\r\s]*\()

Replace with:

${prefix}std::${body}${postfix}

cin
Find what:

(?<!\b[\n\r\s]*::[\n\r\s]*)\bcin(?<postfix>[\n\r\s]*(\>\>|\.))

Replace with:

std::cin${postfix}

ios
Find what:

(?<!\b[\n\r\s]*::[\n\r\s]*)\bios(?<postfix>[\n\r\s]*::)

Replace with:

std::ios${postfix}

filebuf, streambuf, streampos, ifstream, ofstream
Find what:

(?<!\b[\n\r\s]*::[\n\r\s]*)\b(?<body>filebuf|streambuf|streampos|ifstream|ofstream)\b

Replace with:

std::${body}

istream, ostream, fstream
Find what:

(?<!(\b[\n\r\s]*::[\n\r\s]*)|(#\s*include\s*<))\b(?<body>istream|ostream|fstream)\b

Replace with:

std::${body}

cout, cerr
Find what:

(?<!\b[\n\r\s]*\:\:[\n\r\s]*)\b(?<body>cout|cerr)(?<postfix>[\n\r\s]*(\<\<|\.))

Replace with:

std::${body}${postfix}

endl
Find what:

(?<prefix>\<\<[\n\r\s]*)endl\b(?<postfix>[\n\r\s]*(\<\<|;))

Replace with:

${prefix}std::endl${postfix}

Some of changes were done via the specially created compilation error fixer (its source code written in C++17 is attached, look at the file CompilationErrorFixer.cxx, [archived tracker link removed]). This program parses a build output of Microsoft Visual C++ compiler and tries to fix found compilation errors following the user-defined replacement rules. An example of the file containing such rules is attached (compilation_error_replacement_rules.txt, [archived tracker link removed]). An example of a command line to start compilation error fixer application:

CompilationErrorFixer.exe compilation_error_replacement_rules.txt build_output.txt

The compilation error fixer was mostly used to rename the manipulator endl (defined in Message_Messenger.hxx) used with Message_Messenger class (there were about 2,000 places in the source files where this manipulator was used).

The total number of the files that were changed in OCCT: 961.

21Commenter 22019-08-13 11:35

Branch [archived branch] has been created by Commenter 3.

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Detailed log of new commits:

Author: Commenter 3
Date: Tue Aug 13 11:33:20 2019 +0300

    0008239: Foundation Classes - directive "using namespace std" doesn't allow to build application with OCC and other 3rd party libraries

    Standard_Stream.hxx no more adds "using std::" entities.

22Commenter 32019-08-13 13:51

Please raise the patch (CR08239_2 in OCCT and CR30895 from Products from another issue).

http://jenkins-test-12.nnov.opencascade.com:8080/view/CR08239_2-CR30895-KGV/

23Commenter 12019-08-13 19:55

Combination -
OCCT branch : [archived branch]
master SHA - [revision removed]
[revision removed]
Products branch : [archived branch] SHA - [revision removed]
was compiled on Linux, MacOS and Windows platforms and tested in optimize mode.

Number of compiler warnings:
No new/fixed warnings

Regressions/Differences/Improvements:
No regressions/differences

CPU differences:
Debian80-64:
OCCT
Total CPU difference: 16243.920000000046 / 16274.830000000024 [-0.19%]
Products
Total CPU difference: 10479.200000000044 / 10475.390000000047 [+0.04%]
Windows-64-VC14:
OCCT
Total CPU difference: 17671.03125 / 17627.84375 [+0.24%]
Products
Total CPU difference: 12057.671875 / 11990.921875 [+0.56%]

Image differences :
No differences that require special attention

Memory differences :
No differences that require special attention

24Commenter 22019-08-17 12:24

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25Commenter 22019-08-17 12:24

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26Commenter 22019-08-17 12:24

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