[#3336] do not add not-found tool paths

src/CHANGES.txt

@@ -13,6 +13,8 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
     - Use importlib to dynamically load tool and platform modules instead of imp module
     - sconsign: default to .sconsign.dblite if no filename is specified.
       Be more informative in case of unsupported pickle protocol (py2 only).
+    - Fix issue #3336 - on Windows, paths were being added to PATH even if
+      tools were not found in those paths.
 
   From John Doe:
 

src/engine/SCons/Tool/__init__.py

@@ -1318,28 +1318,31 @@ def tool_list(platform, env):
 
 def find_program_path(env, key_program, default_paths=[]):
     """
-    Find the location of key_program and then return the path it was located at.
-    Checking the default install locations.
-    Mainly for windows where tools aren't all installed in /usr/bin,etc
-    :param env: Current Environment()
-    :param key_program: Program we're using to locate the directory to add to PATH.
+    Find the location of a tool using various means.
+
+    Mainly for windows where tools aren't all installed in /usr/bin, etc.
+
+    :param env: Current Construction Environment.
+    :param key_program: Tool to locate.
+    :param default_paths: List of additional paths this tool might be found in.
     """
     # First search in the SCons path
     path = env.WhereIs(key_program)
-    if (path):
+    if path:
         return path
-    # then the OS path:
+
+    # Then in the OS path
     path = SCons.Util.WhereIs(key_program)
-    if (path):
+    if path:
         return path
 
-    # If that doesn't work try default location for mingw
+    # Finally, add the defaults and check again. Do not change
+    # ['ENV']['PATH'] permananetly, the caller can do that if needed.
     save_path = env['ENV']['PATH']
     for p in default_paths:
         env.AppendENVPath('PATH', p)
     path = env.WhereIs(key_program)
-    if not path:
-        env['ENV']['PATH'] = save_path
+    env['ENV']['PATH'] = save_path
     return path
 
 # Local Variables:

src/engine/SCons/Tool/lex.py

@@ -70,11 +70,15 @@ def lexEmitter(target, source, env):
 
 def get_lex_path(env, append_paths=False):
     """
-    Find the a path containing the lex or flex binaries. If a construction 
-    environment is passed in then append the path to the ENV PATH.
+    Find the path to the lex tool, searching several possible names
+
+    Only called in the Windows case, so the default_path
+    can be Windows-specific
+
+    :param env: current construction environment
+    :param append_paths: if set, add the path to the tool to PATH
+    :return: path to lex tool, if found
     """
-    # save existing path to reset if we don't want to append any paths
-    envPath = env['ENV']['PATH']
     bins = ['flex', 'lex', 'win_flex']
 
     for prog in bins:
@@ -83,9 +87,7 @@ def get_lex_path(env, append_paths=False):
             prog, 
             default_paths=CHOCO_DEFAULT_PATH + MINGW_DEFAULT_PATHS + CYGWIN_DEFAULT_PATHS )
         if bin_path:
-            if not append_paths:
-                env['ENV']['PATH'] = envPath
-            else:
+            if append_paths:
                 env.AppendENVPath('PATH', os.path.dirname(bin_path))
             return bin_path
     SCons.Warnings.Warning('lex tool requested, but lex or flex binary not found in ENV PATH')
@@ -113,7 +115,8 @@ def generate(env):
     env["LEXFLAGS"] = SCons.Util.CLVar("")
 
     if sys.platform == 'win32':
-        get_lex_path(env, append_paths=True)
+        # ignore the return - we do not need the full path here
+        _ = get_lex_path(env, append_paths=True)
         env["LEX"] = env.Detect(['flex', 'lex', 'win_flex'])
         if not env.get("LEXUNISTD"):
             env["LEXUNISTD"] = SCons.Util.CLVar("")

src/engine/SCons/Tool/swig.py

@@ -184,9 +184,10 @@ def generate(env):
 
     from SCons.Platform.mingw import MINGW_DEFAULT_PATHS
     from SCons.Platform.cygwin import CYGWIN_DEFAULT_PATHS
+    from SCons.Platform.win32 import CHOCO_DEFAULT_PATH
 
     if sys.platform == 'win32':
-        swig = SCons.Tool.find_program_path(env, 'swig', default_paths=MINGW_DEFAULT_PATHS + CYGWIN_DEFAULT_PATHS + [r'C:\ProgramData\chocolatey\bin'] )
+        swig = SCons.Tool.find_program_path(env, 'swig', default_paths=MINGW_DEFAULT_PATHS + CYGWIN_DEFAULT_PATHS + CHOCO_DEFAULT_PATH)
         if swig:
             swig_bin_dir = os.path.dirname(swig)
             env.AppendENVPath('PATH', swig_bin_dir)

src/engine/SCons/Tool/yacc.py

@@ -100,11 +100,15 @@ def yyEmitter(target, source, env):
 
 def get_yacc_path(env, append_paths=False):
     """
-    Find the a path containing the lex or flex binaries. If a construction 
-    environment is passed in then append the path to the ENV PATH.
+    Find the path to the yacc tool, searching several possible names
+
+    Only called in the Windows case, so the default_path
+    can be Windows-specific
+
+    :param env: current construction environment
+    :param append_paths: if set, add the path to the tool to PATH
+    :return: path to yacc tool, if found
     """
-    # save existing path to reset if we don't want to append any paths
-    envPath = env['ENV']['PATH']
     bins = ['bison', 'yacc', 'win_bison']
 
     for prog in bins:
@@ -113,12 +117,11 @@ def get_yacc_path(env, append_paths=False):
             prog, 
             default_paths=CHOCO_DEFAULT_PATH + MINGW_DEFAULT_PATHS + CYGWIN_DEFAULT_PATHS )
         if bin_path:
-            if not append_paths:
-                env['ENV']['PATH'] = envPath
-            else:
+            if append_paths:
                 env.AppendENVPath('PATH', os.path.dirname(bin_path))
             return bin_path
-    SCons.Warnings.Warning('lex tool requested, but lex or flex binary not found in ENV PATH')
+    SCons.Warnings.Warning('yacc tool requested, but yacc or bison binary not found in ENV PATH')
+
 
 def generate(env):
     """Add Builders and construction variables for yacc to an Environment."""
@@ -148,7 +151,8 @@ def generate(env):
             SCons.Warnings.Warning('yacc tool requested, but bison binary not found in ENV PATH')
 
     if sys.platform == 'win32':
-        get_yacc_path(env, append_paths=True)
+        # ignore the return - we do not need the full path here
+        _ = get_yacc_path(env, append_paths=True)
         env["YACC"] = env.Detect(['bison', 'yacc', 'win_bison'])
     else:
         env["YACC"] = env.Detect(["bison", "yacc"])
@@ -162,7 +166,10 @@ def generate(env):
     env['YACCVCGFILESUFFIX'] = '.vcg'
 
 def exists(env):
-    return env.Detect(['bison', 'yacc'])
+    if sys.platform == 'win32':
+        return get_yacc_path(env)
+    else:
+        return env.Detect(['bison', 'yacc'])
 
 # Local Variables:
 # tab-width:4

test/LEX/live_mingw.py

@@ -41,7 +41,7 @@
     test.skip_test('Not windows environment; skipping test.\n')
 
 if not test.where_is('gcc'):
-        test.skip_test('No mingw or cygwin on windows; skipping test.\n')
+        test.skip_test('No mingw or cygwin build environment found; skipping test.\n')
 
 lex = test.where_is('lex') or test.where_is('flex')