Verilator 5.034 fails to compile c++ sources as it uses syntax for c++17 while the CFLAGS passed to it specify c++14.

Testing

Before this patch I got the following error when testing my design with:

"UartTx should send" in {
  simulate(new UartTx(8, None, StopBitsOne())) { dut => {} }
}  

[info] g++ -Os  -I. -Wall -Wextra -Wfloat-conversion -Wlogical-op -Werror -MMD -I/usr/share/verilator/include -I/usr/share/verilator/include/vltstd -DVM_COVERAGE=0 -DVM_SC=0 -DVM_TIMING=0 -DVM_TRACE=0 -DVM_TRACE_FST=0 -DVM_TRACE_VCD=0 -faligned-new -fcf-protection=none -Wno-bool-operation -Wno-shadow -Wno-sign-compare -Wno-subobject-linkage -Wno-tautological-compare -Wno-uninitialized -Wno-unused-but-set-parameter -Wno-unused-but-set-variable -Wno-unused-parameter -Wno-unused-variable    -std=c++14 -I/home/lg/programming/chisel/chuart/build/chiselsim/UartSpec/UartTx-should-send/workdir-verilator -DSVSIM_ENABLE_VERILATOR_SUPPORT   -c -o VsvsimTestbench__ALL.o VsvsimTestbench__ALL.cpp
[info] simulation-driver.cpp: In function ‘int simulation_final()’:
[info] simulation-driver.cpp:877:9: error: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Werror=c++17-extensions]
[info]   877 |   auto &[command, cycles] = state.outstandingCommand;

After this patch, the test succeeds.

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix

Desired Merge Strategy

• Rebase: You will rebase the PR onto master and it will be merged with a merge commit.

Release Notes

Verilator CFLAGS bumped from c++14 to c++17

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash) and clean up the commit message.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.