-gsource-map does not work on Windows if username contains non-ASCII Unicode characters.

[juj]

If username has non-ASCII Unicode characters, then on Windows the TEMP environment variable will point to a path that has Unicode chars in it (e.g. TEMP=C:\Users\Matti Meikäläinen\AppData\Local\Temp)

In such a mode, using -gsource-map command line flag fails on Windows.

e.g.

C:\ä ö\emsdk\emscripten\main>set TEMP
TEMP=C:\ä ö\temp

C:\ä ö\emsdk\emscripten\main>test\runner other.test_wasm_sourcemap_relative_paths
Running test_other: (1 tests)
test_wasm_sourcemap_relative_paths (test_other.other.test_wasm_sourcemap_relative_paths) ... a.cpp a.cpp
   a.cpp
     same CWD for compiler and linker
FAIL

======================================================================
FAIL: test_wasm_sourcemap_relative_paths (test_other.other.test_wasm_sourcemap_relative_paths)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\ä ö\emsdk\emscripten\main\test\test_other.py", line 10781, in test_wasm_sourcemap_relative_paths
    test('a.cpp')
    ~~~~^^^^^^^^^
  File "C:\ä ö\emsdk\emscripten\main\test\test_other.py", line 10774, in test
    self.assertIn('"%s"' % expected_source_map_path, read_file('a.out.wasm.map'))
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: '"a.cpp"' not found in '{"version":3,"sources":["../../../../../../303/244 /303/266/emsdk/emscripten/main/out/test/a.cpp","/emsdk/emscripten/system/lib/compiler-rt/stack_ops.S","/emsdk/emscripten/system/lib/compiler-rt/stack_limits.S","/emsdk/emscripten/system/lib/pthread/library_pthread_stub.c","/emsdk/emscripten/system/lib/libc/musl/src/stdio/ofl.c","/emsdk/emscripten/system/lib/libc/musl/src/stdio/__lockfile.c","/emsdk/emscripten/system/lib/libc/musl/src/stdio/fflush.c"],"sourcesContent":[],"names":[],"mappings":"6XAOA,iCACE,QAAA,kBCQF,GACA,MACA,KAKA,MAEA,EAEA,CAEA,EACA,CACA,EACA,MACA,EACA,EAIA,OACA,ECWA,OAEA,MAMA,MAGA,EACA,CACA,EACA,CACA,MAEA,EAYA,OACA,MACA,CACA,EAnDA,OACA,EAIA,OACA,GCmVwB,GAEE,GChXzB,YACA,MAAA,GAKA,YACD,ECbA,GAaC,GASD,MCjBK,UAEC,cAA2B,SAAP,aACpB,UAA2B,SAAP,MAAH,MAEb,QAAV,GAAE,KACC,oBAAA,GAAA,QAEA,IADO,OAAW,KAAN,GAAkB,QAAH,MAC3B,eAHH,KAAE,MAKA,MAyBF,IApBC,kBAAA,GAAA,QAkBA,IAfO,WAAW,KAAN,SACX,iBACQ,KAAJ,MACH,QAMK,OAAW,OAAN,KAA8B,OAAP,GAAX,0BAGL,OAAU,OACrB,GAER,cAED,EAAA"}'

----------------------------------------------------------------------
Ran 1 test in 0.533s

FAILED (failures=1)

C:\ä ö\emsdk\emscripten\main>

It looks like the source map generation has generated an incorrect source path:

"../../../../../../303/244 /303/266/emsdk/emscripten/main/out/test/a.cpp"

when it was expected to have resolved to just a.cpp.

If the TEMP directory points to a path without Unicode chars, then the test passes on Windows.