Update the visual studio version checking logic

This PR updates the `_is_vs_2017_or_2019` function to specify the visual studio version based on the contents of the VC folder instead of depending on the parent directories of VC.

This is helpful in cases where `BAZEL_VC` points to a custom location of VC.

Fixes: bazelbuild#11259

Closes bazelbuild#12586.

PiperOrigin-RevId: 344817390

tools/cpp/windows_cc_configure.bzl

@@ -254,14 +254,17 @@ def find_vc_path(repository_ctx):
     auto_configure_warning_maybe(repository_ctx, "Visual C++ build tools found at %s" % vc_dir)
     return vc_dir
 
-def _is_vs_2017_or_2019(vc_path):
-    """Check if the installed VS version is Visual Studio 2017."""
+def _is_vs_2017_or_2019(repository_ctx, vc_path):
+    """Check if the installed VS version is Visual Studio 2017 or 2019."""
 
-    # In VS 2017 and 2019, the location of VC is like:
-    # C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\
-    # In VS 2015 or older version, it is like:
-    # C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\
-    return vc_path.find("2017") != -1 or vc_path.find("2019") != -1
+    # The layout of VC folder in VS 2017 and 2019 is different from that in VS 2015 and older versions.
+    # In VS 2017 and 2019, it contains only three directories:
+    # "Auxiliary", "Redist", "Tools"
+
+    vc_2017_or_2019_contents = ["auxiliary", "redist", "tools"]
+    vc_path_contents = [d.basename.lower() for d in repository_ctx.path(vc_path).readdir()]
+    vc_path_contents = sorted(vc_path_contents)
+    return vc_path_contents == vc_2017_or_2019_contents
 
 def _is_msbuildtools(vc_path):
     """Check if the installed VC version is from MSBuildTools."""
@@ -272,7 +275,7 @@ def _is_msbuildtools(vc_path):
 
 def _find_vcvars_bat_script(repository_ctx, vc_path):
     """Find batch script to set up environment variables for VC. Doesn't %-escape the result."""
-    if _is_vs_2017_or_2019(vc_path):
+    if _is_vs_2017_or_2019(repository_ctx, vc_path):
         vcvars_script = vc_path + "\\Auxiliary\\Build\\VCVARSALL.BAT"
     else:
         vcvars_script = vc_path + "\\VCVARSALL.BAT"
@@ -290,7 +293,7 @@ def _is_support_vcvars_ver(vc_full_version):
 
 def _is_support_winsdk_selection(repository_ctx, vc_path):
     """Windows SDK selection is supported with VC 2017 / 2019 or with full VS 2015 installation."""
-    if _is_vs_2017_or_2019(vc_path):
+    if _is_vs_2017_or_2019(repository_ctx, vc_path):
         return True
 
     # By checking the source code of VCVARSALL.BAT in VC 2015, we know that
@@ -316,7 +319,7 @@ def _get_vc_env_vars(repository_ctx, vc_path, msvc_vars_x64, target_arch):
         dictionary of envvars
     """
     env = {}
-    if _is_vs_2017_or_2019(vc_path):
+    if _is_vs_2017_or_2019(repository_ctx, vc_path):
         lib = msvc_vars_x64["%{msvc_env_lib_x64}"]
         full_version = _get_vc_full_version(repository_ctx, vc_path)
         tools_path = "%s\\Tools\\MSVC\\%s\\bin\\HostX64\\%s" % (vc_path, full_version, target_arch)
@@ -360,7 +363,7 @@ def setup_vc_env_vars(repository_ctx, vc_path, envvars = [], allow_empty = False
 
     # Get VC version set by user. Only supports VC 2017 & 2019.
     vcvars_ver = ""
-    if _is_vs_2017_or_2019(vc_path):
+    if _is_vs_2017_or_2019(repository_ctx, vc_path):
         full_version = _get_vc_full_version(repository_ctx, vc_path)
 
         # Because VCVARSALL.BAT is from the latest VC installed, so we check if the latest
@@ -441,7 +444,7 @@ def _find_msvc_tools(repository_ctx, vc_path, target_arch = "x64"):
 def find_msvc_tool(repository_ctx, vc_path, tool, target_arch = "x64"):
     """Find the exact path of a specific build tool in MSVC. Doesn't %-escape the result."""
     tool_path = None
-    if _is_vs_2017_or_2019(vc_path) or _is_msbuildtools(vc_path):
+    if _is_vs_2017_or_2019(repository_ctx, vc_path) or _is_msbuildtools(vc_path):
         full_version = _get_vc_full_version(repository_ctx, vc_path)
         if full_version:
             tool_path = "%s\\Tools\\MSVC\\%s\\bin\\HostX64\\%s\\%s" % (vc_path, full_version, target_arch, tool)