Update that helps diagnose and in some cases circumvent potential issues with MSVC and GNU utilities

tools/gen_asm_script.cmd

@@ -1,37 +1,56 @@
 @echo off
 setlocal enableextensions
 
+:: Countermeasure vs tainted build environment by known third party utilities
+set FIND=find
+find /? >nul 2>&1
+if errorlevel 1 (
+	echo WARNING: GNU utilities in PATH can break MSVC
+	echo.
+	set FIND=findstr
+)
+
+:: Anchor to the project file path, otherwise the arguments would be invalid:
+::
+:: * In theory this is unnecessary, but it makes the process more transparent
+::   to people unfamiliar with VS's not-so-well-explained behaviors
+::
+pushd "%~dp0..\projects\msvc\"
+if errorlevel 1 exit /b 101
+
 :: Validating arguments passed from Visual Studio to use as variables:
 ::
 :: * Arguments with conflicting syntax can terminate the script abruptly
 :: * 'GAS_EXTRA' argument isn't used in some cases
 ::
+set GAS_SRCDIR=
+set GAS_OBJDIR=
 set GAS_EXTRA=
 for /f "tokens=1,2*" %%A in ('echo %*') do (
-set GAS_SRCDIR=%%A
+	set GAS_SRCDIR=%%A
-set GAS_OBJDIR=%%B
+	set GAS_OBJDIR=%%B
-set GAS_EXTRA=%%C
+	set GAS_EXTRA=%%C
 )
 set GAS_CLARG=%GAS_OBJDIR%
 if defined GAS_EXTRA set GAS_CLARG=%GAS_OBJDIR% %GAS_EXTRA%
 
 :: "Anti-PEBCAK":
 ::
-:: * Ensures that "Item A" and "Item B" exist, and send an error signal if not
+:: * Ensure that 'GAS_SRCDIR' and 'GAS_OBJDIR' exist or are defined and send an
-:: * The sole purpose of this code is to make the script fail outside VS
+::   error signal if not
 ::
-if not exist mupen64plus-core.vcxproj exit /b 202
+if not exist "%GAS_SRCDIR%asm_defines.c" exit /b 202
-if not exist "%GAS_SRCDIR%asm_defines.c" exit /b 303
+if not defined GAS_OBJDIR exit /b 303
 
 :: Legacy code adaptation for this script:
 ::
 :: * Delete the libraries previously generated by 'gawk' or this script
-:: * CL's stuff/witchcraft, if all goes well it will generate "Item C"
+:: * CL's stuff/witchcraft, if all goes well it will generate 'asm_defines.obj'
 ::
 del /f /q "%GAS_SRCDIR%asm_defines_*" 2>nul
 cl /c /Fo%GAS_CLARG% /I ..\..\src "%GAS_SRCDIR%asm_defines.c"
 
-:: If "Item C" does not exist, send error
+:: If 'asm_defines.obj' does not exist, send error
 if not exist "%GAS_OBJDIR%asm_defines.obj" exit /b 404
 if "%USE_GAWK%" NEQ "1" goto native
 
@@ -48,8 +67,8 @@ goto log
 
 :: Adaptation of 'gen_asm_defines.awk' / 'gen_asm_script.sh':
 ::
-:: 1. Display 'asm_defines.obj' (aka "Item C") as a list, looking only
+:: 1. Display 'asm_defines.obj' as a list, looking only for patterns
-::    for patterns '@ASM_DEFINE'
+::    '@ASM_DEFINE'
 :: 2. Sort for easy reading, the result is interpreted as an array
 ::    with ' ' as default delimiter in the 'for' command
 :: 3. The for's 'tokens=2,3' ignores pattern "1" (@ASM_DEFINE) and anything
@@ -57,9 +76,9 @@ goto log
 :: 4. Print current values and repeat steps 3 and 4 on the next line
 ::    until EOL is reached
 ::
-for /f "tokens=2,3" %%J in ('type "%GAS_OBJDIR%asm_defines.obj" ^| find "@ASM_DEFINE" ^| sort') do (
+for /f "tokens=2,3" %%J in ('type "%GAS_OBJDIR%asm_defines.obj" ^| %FIND% "@ASM_DEFINE" ^| sort') do (
-echo %%define %%J ^(%%K^)>>"%GAS_SRCDIR%asm_defines_nasm.h"
+	echo %%define %%J ^(%%K^)>>"%GAS_SRCDIR%asm_defines_nasm.h"
-echo #define %%J ^(%%K^)>>"%GAS_SRCDIR%asm_defines_gas.h"
+	echo #define %%J ^(%%K^)>>"%GAS_SRCDIR%asm_defines_gas.h"
 )
 :log