Fix combined use of compiler launcher with lint tools

When using ccache with clang-tidy, ccache needs to wrap compiler
invocation, rather than cmake invocation.  But it needs to do it without
affecting the command line that iwyu-like tools are receiving.

With this fix, if __run_co_compile is used, compile launcher is passed
using the new --launcher option, but if __run_co_compile is not needed,
compiler launcher is prepended to the command line as before.

To better illustrate the change: with this fix if running clang-tidy
with CXX_COMPILER_LAUNCHER set to "/usr/bin/time;-p;ccache" (time -p
added strictly for illustration purposes), the command line changes
from:

    /usr/bin/time -p ccache cmake -E __run_co_compile \
        --tidy=clang-tidy ... -- g++ ...

to:

    cmake -E __run_co_compile \
        --launcher="/usr/bin/time;-p;ccache" \
        --tidy=clang-tidy ... -- g++ ...

This allows the compiler to be run via the launcher, but leaves tidy
(& friends) invocations unaffected.

Fixes: #16493

1 files changed, 17 insertions, 9 deletions

diff --git a/Source/cmcmd.cxx b/Source/cmcmd.cxx
index e7d92d4..6f3a90f 100644
--- a/Source/cmcmd.cxx
+++ b/Source/cmcmd.cxx
@@ -359,7 +359,8 @@ struct CoCompileJob
 int cmcmd::HandleCoCompileCommands(std::vector<std::string>& args)
 {
   std::vector<CoCompileJob> jobs;
-  std::string sourceFile; // store --source=
+  std::string sourceFile;             // store --source=
+  std::vector<std::string> launchers; // store --launcher=
 
   // Default is to run the original command found after -- if the option
   // does not need to do that, it should be specified here, currently only
@@ -390,15 +391,17 @@ int cmcmd::HandleCoCompileCommands(std::vector<std::string>& args)
           }
         }
       }
-      if (cmHasLiteralPrefix(arg, "--source=")) {
-        sourceFile = arg.substr(9);
-        optionFound = true;
-      }
-      // if it was not a co-compiler or --source then error
       if (!optionFound) {
-        std::cerr << "__run_co_compile given unknown argument: " << arg
-                  << "\n";
-        return 1;
+        if (cmHasLiteralPrefix(arg, "--source=")) {
+          sourceFile = arg.substr(9);
+        } else if (cmHasLiteralPrefix(arg, "--launcher=")) {
+          cmSystemTools::ExpandListArgument(arg.substr(11), launchers, true);
+        } else {
+          // if it was not a co-compiler or --source/--launcher then error
+          std::cerr << "__run_co_compile given unknown argument: " << arg
+                    << "\n";
+          return 1;
+        }
       }
     } else { // if not doing_options then push to orig_cmd
       orig_cmd.push_back(arg);
@@ -436,6 +439,11 @@ int cmcmd::HandleCoCompileCommands(std::vector<std::string>& args)
     return 0;
   }
 
+  // Prepend launcher argument(s), if any
+  if (!launchers.empty()) {
+    orig_cmd.insert(orig_cmd.begin(), launchers.begin(), launchers.end());
+  }
+
   // Now run the real compiler command and return its result value
   int ret;
   if (!cmSystemTools::RunSingleCommand(orig_cmd, nullptr, nullptr, &ret,