Catch is susceptible to VC12 bug: do-while loop within range-based-for fails to compile.

[martinmoene]

Compiling:

#define CATCH_CONFIG_MAIN
#include "catch.hpp"

TEST_CASE( "Syntax error with VC12", "" )
{
    for ( auto x : { 1 , 2, 3 } )
        REQUIRE( x < 3.14 );
}

yields:

range-for-catch.cpp(7) : error C2059: syntax error : '}'

This VC12 behaviour is reported as do-while loop within range-based-for fails to compile.

See also Range-for, with try/catch statement, not compiling.

Workaround for users of Catch:

TEST_CASE( "Enclose in block to compile with VC12", "" )
{
    for ( auto x : { 1 , 2, 3 } )
    {
        REQUIRE( x < 3.14 );
    }
}

With Catch REQUIRE expanded and simplified this boils down to:

void fail()
{
    for ( auto x: { 1, 2, 3 } )
        do
        {
            try { }
            catch( std::exception const & ) {} 
        }
        while ( false );
}

Workaround is to enclose do {} while(); in block:

void pass()
{
    for ( auto x: { 1, 2, 3 } )
    {
        do
        {
            try { }
            catch( std::exception const & ) {} 
        }
        while ( false );
    }
}

This changes REQUIRE() from an iteration statement into a compound statement. What consequences may this have, if any?

[Kosta-Github]

honestly, I don't spot the difference between the two versions...

[PureAbstract]

@Kosta-Github The workaround version has braces around the do-while. They (should!) be semantically identical

[Kosta-Github]

ah, I see, hard to spot due to the same level of indention... :-)

[martinmoene]

@Kosta-Github How w'd you suggest to format both fragments ? ;)

Improved original message (hopefully).

[philsquared]

Thanks for this, Martin. An entry for the FAQ, I think (which I'll be putting together shortly!)

[Kosta-Github]

@philsquared why not adding the additional { and } to the REQUIRE macro inside of CATCH? I guess that is what @martinmoene also suggests, right?

[martinmoene]

@Kosta-Github, @philsquared : right :)

[philsquared]

because that would defeat the purpose of the do...while idiom in the first place (to require the ;, without generating warnings about redundant ;s - while being usable in block statements.

[martinmoene]

@philsquared Another good reason not to deform CATCH ;)

[philsquared]

Not sure what deformation you're referring to?

[martinmoene]

Bending code to bypass a bug leading to unwanted or less clear code...

[Trass3r]

Should be closed then.

[martinmoene]

mmm,

• will not fix, and
• useful information for some users of Catch

When closing the issue, the information moves out of sight; what to do?