From 83804e2bc65fb3b4aba0757ed0061d84a5b65d94 Mon Sep 17 00:00:00 2001
From: James Henderson <james.henderson@sony.com>
Date: Mon, 17 May 2021 15:02:29 +0100
Subject: [PATCH] [lit] Stop using PATH to lookup clang/lld/lldb unless
 requested

This patch stops lit from looking on the PATH for clang, lld and other
users of use_llvm_tool (currently only the debuginfo-tests) unless the
call explicitly requests to opt into using the PATH. When not opting in,
tests will only look in the build directory.

See the mailing list thread starting from
https://lists.llvm.org/pipermail/llvm-dev/2021-May/150421.html.

See the review for details of why decisions were made about when still
to use the PATH.

Reviewed by: thopre

Differential Revision: https://reviews.llvm.org/D102630
---
 utils/lit/lit/llvm/config.py | 39 +++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/utils/lit/lit/llvm/config.py b/utils/lit/lit/llvm/config.py
index 6ff3cba00f3..94824cd3477 100644
--- a/utils/lit/lit/llvm/config.py
+++ b/utils/lit/lit/llvm/config.py
@@ -401,10 +401,11 @@ class LLVMConfig(object):
 
         self.add_err_msg_substitutions()
 
-    def use_llvm_tool(self, name, search_env=None, required=False, quiet=False):
+    def use_llvm_tool(self, name, search_env=None, required=False, quiet=False,
+                      use_installed=False):
         """Find the executable program 'name', optionally using the specified
-        environment variable as an override before searching the
-        configuration's PATH."""
+        environment variable as an override before searching the build directory
+        and then optionally the configuration's PATH."""
         # If the override is specified in the environment, use it without
         # validation.
         tool = None
@@ -412,7 +413,11 @@ class LLVMConfig(object):
             tool = self.config.environment.get(search_env)
 
         if not tool:
-            # Otherwise look in the path.
+            # Use the build directory version.
+            tool = lit.util.which(name, self.config.llvm_tools_dir)
+
+        if not tool and use_installed:
+            # Otherwise look in the path, if enabled.
             tool = lit.util.which(name, self.config.environment['PATH'])
 
         if required and not tool:
@@ -429,11 +434,11 @@ class LLVMConfig(object):
         return tool
 
     def use_clang(self, additional_tool_dirs=[], additional_flags=[],
-                  required=True):
+                  required=True, use_installed=False):
         """Configure the test suite to be able to invoke clang.
 
         Sets up some environment variables important to clang, locates a
-        just-built or installed clang, and add a set of standard
+        just-built or optionally an installed clang, and add a set of standard
         substitutions useful to any test suite that makes use of clang.
 
         """
@@ -497,7 +502,8 @@ class LLVMConfig(object):
 
         # Discover the 'clang' and 'clangcc' to use.
         self.config.clang = self.use_llvm_tool(
-            'clang', search_env='CLANG', required=required)
+            'clang', search_env='CLANG', required=required,
+            use_installed=use_installed)
         if self.config.clang:
           self.config.available_features.add('clang')
           builtin_include_dir = self.get_clang_builtin_include_dir(
@@ -569,11 +575,12 @@ class LLVMConfig(object):
             (' %clang-cl ',
              '''\"*** invalid substitution, use '%clang_cl'. ***\"'''))
 
-    def use_lld(self, additional_tool_dirs=[], required=True):
+    def use_lld(self, additional_tool_dirs=[], required=True,
+                use_installed=False):
         """Configure the test suite to be able to invoke lld.
 
         Sets up some environment variables important to lld, locates a
-        just-built or installed lld, and add a set of standard
+        just-built or optionally an installed lld, and add a set of standard
         substitutions useful to any test suite that makes use of lld.
 
         """
@@ -593,12 +600,16 @@ class LLVMConfig(object):
 
         self.with_environment('LD_LIBRARY_PATH', paths, append_path=True)
 
-        # Discover the 'clang' and 'clangcc' to use.
+        # Discover the LLD executables to use.
 
-        ld_lld = self.use_llvm_tool('ld.lld', required=required)
-        lld_link = self.use_llvm_tool('lld-link', required=required)
-        ld64_lld = self.use_llvm_tool('ld64.lld', required=required)
-        wasm_ld = self.use_llvm_tool('wasm-ld', required=required)
+        ld_lld = self.use_llvm_tool('ld.lld', required=required,
+                                    use_installed=use_installed)
+        lld_link = self.use_llvm_tool('lld-link', required=required,
+                                      use_installed=use_installed)
+        ld64_lld = self.use_llvm_tool('ld64.lld', required=required,
+                                      use_installed=use_installed)
+        wasm_ld = self.use_llvm_tool('wasm-ld', required=required,
+                                     use_installed=use_installed)
 
         was_found = ld_lld and lld_link and ld64_lld and wasm_ld
         tool_substitutions = []