[clang] [clang][scan-build] Treat --use-cc and --use-c++ as shell commands (PR #131932)

[Donát Nagy via cfe-commits]

================
@@ -51,63 +51,40 @@ sub silent_system {
 # Compiler command setup.
 ##===----------------------------------------------------------------------===##
 
-# Search in the PATH if the compiler exists
-sub SearchInPath {
-    my $file = shift;
-    foreach my $dir (split (':', $ENV{PATH})) {
-        if (-x "$dir/$file") {
-            return 1;
-        }
-    }
-    return 0;
-}
-
-my $Compiler;
-my $Clang;
-my $DefaultCCompiler;
-my $DefaultCXXCompiler;
-my $IsCXX;
-my $AnalyzerTarget;
-
-# If on OSX, use xcrun to determine the SDK root.
-my $UseXCRUN = 0;
-
-if (`uname -s` =~ m/Darwin/) {
-  $DefaultCCompiler = 'clang';
-  $DefaultCXXCompiler = 'clang++';
-  # Older versions of OSX do not have xcrun to
-  # query the SDK location.
-  if (-x "/usr/bin/xcrun") {
-    $UseXCRUN = 1;
-  }
-} elsif (`uname -s` =~ m/(FreeBSD|OpenBSD)/) {
-  $DefaultCCompiler = 'cc';
-  $DefaultCXXCompiler = 'c++';
-} else {
-  $DefaultCCompiler = 'gcc';
-  $DefaultCXXCompiler = 'g++';
-}
-
-if ($FindBin::Script =~ /c\+\+-analyzer/) {
-  $Compiler = $ENV{'CCC_CXX'};
-  if (!defined $Compiler || (! -x $Compiler && ! SearchInPath($Compiler))) { $Compiler = $DefaultCXXCompiler; }
-
-  $Clang = $ENV{'CLANG_CXX'};
-  if (!defined $Clang || ! -x $Clang) { $Clang = 'clang++'; }
-
-  $IsCXX = 1
+{
+  my ($DefaultCCompiler, $DefaultCXXCompiler);
+
+  my $os = `uname -s`;
+  if ($os =~ m/Darwin/) {
+    $DefaultCCompiler = 'clang';
+    $DefaultCXXCompiler = 'clang++';
+  } elsif ($os =~ m/(FreeBSD|OpenBSD)/) {
+    $DefaultCCompiler = 'cc';
+    $DefaultCXXCompiler = 'c++';
+  } else {
+    $DefaultCCompiler = 'gcc';
+    $DefaultCXXCompiler = 'g++';
+  }
+
+  sub DetermineCompiler {
+    my ($is_cxx) = @_;
+    my $default = $is_cxx ? $DefaultCXXCompiler : $DefaultCCompiler;
+    my $opt = $ENV{$is_cxx ? 'CCC_CXX' : 'CCC_CC'};
+    return defined $opt ? shellwords($opt) : $default;
+  }
 }
-else {
-  $Compiler = $ENV{'CCC_CC'};
-  if (!defined $Compiler || (! -x $Compiler && ! SearchInPath($Compiler))) { $Compiler = $DefaultCCompiler; }
-
-  $Clang = $ENV{'CLANG'};
-  if (!defined $Clang || ! -x $Clang) { $Clang = 'clang'; }
 
-  $IsCXX = 0
+sub DetermineClang {
+  my ($is_cxx) = @_;
----------------
NagyDonat wrote:

Bikeshedding: Please use `$UpperCamelCase` within the new functions `DetermineCompiler` / `DetermineClang` because it's a bit jarring when `$IsCXX` / `$is_cxx` appears both in `$UpperCamelCase` and in `$snake_case`. I see that these styles both appear in the script, but in these parts  `$UpperCamelCase` is more common, so I think it would be better if you used that.

https://github.com/llvm/llvm-project/pull/131932