[meson 0.56] Cannot handle spaces in [binaries] paths / string index out of range in ninjabackend.py

[Neumann-A]

Describe the bug

Traceback (most recent call last):
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\mesonmain.py", line 140, in run
    return options.run_func(options)
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\msetup.py", line 253, in run
    app.generate()
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\msetup.py", line 161, in generate
    self._generate(env)
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\msetup.py", line 223, in _generate
    intr.backend.generate()
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\backend\ninjabackend.py", line 533, in generate
    self.write_rules(outfile)
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\backend\ninjabackend.py", line 1122, in write_rules
    b.count_rule_references()
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\backend\ninjabackend.py", line 342, in count_rule_references
    if self._should_use_rspfile():
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\backend\ninjabackend.py", line 336, in _should_use_rspfile
    return self.rule.length_estimate(infilenames,
  File "E:\vcpkg_cache\downloads\tools\meson\meson-0.56.0\mesonbuild\backend\ninjabackend.py", line 273, in length_estimate
    if chunk[1] == '{':
IndexError: string index out of range

[Neumann-A]

added a print(command) in line 269 before the for loop and a print(m) in the loop.
The output is:

"C:/Program$ Files$ (x86)/Microsoft$ Visual$ Studio/2019/Community/VC/Tools/MSVC/14.28.29333/bin/Hostx64/x64/cl.exe" $ARGS /Fo$out "/c" $in
<re.Match object; span=(0, 11), match='"C:/Program'>
<re.Match object; span=(11, 18), match='$ Files'>

[Neumann-A]

Also it worked fine with meson 0.55.1

[Neumann-A]

the important parts of the native file:

[binaries]
mt = 'C:/Program Files (x86)/Windows Kits/10/bin/10.0.19041.0/x64/mt.exe'
c = 'C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.28.29333/bin/Hostx64/x64/cl.exe'
cpp = 'C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.28.29333/bin/Hostx64/x64/cl.exe'
rc = 'C:/Program Files (x86)/Windows Kits/10/bin/10.0.19041.0/x64/rc.exe'
c_ld = 'C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.28.29333/bin/Hostx64/x64/link.exe'
cpp_ld = 'C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.28.29333/bin/Hostx64/x64/link.exe'
cmake = 'C:/Program Files/CMake/bin/cmake.exe'

[Neumann-A]

The regex should probably be:
for m in re.finditer(r'(\${\w+}|\$\w+)?[^$]*', command):
and not
for m in re.finditer(r'(\${\w*}|\$\w*)?[^$]*', command):
cc @bonzini