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, 27 insertions, 14 deletions

diff --git a/Source/cmMakefileTargetGenerator.cxx b/Source/cmMakefileTargetGenerator.cxx
index 73cf1f0..abe5ff3 100644
--- a/Source/cmMakefileTargetGenerator.cxx
+++ b/Source/cmMakefileTargetGenerator.cxx
@@ -643,6 +643,18 @@ void cmMakefileTargetGenerator::WriteObjectBuildFile(
         source.GetFullPath(), workingDirectory, compileCommand);
     }
 
+    // See if we need to use a compiler launcher like ccache or distcc
+    std::string compilerLauncher;
+    if (!compileCommands.empty() && (lang == "C" || lang == "CXX" ||
+                                     lang == "Fortran" || lang == "CUDA")) {
+      std::string const clauncher_prop = lang + "_COMPILER_LAUNCHER";
+      const char* clauncher =
+        this->GeneratorTarget->GetProperty(clauncher_prop);
+      if (clauncher && *clauncher) {
+        compilerLauncher = clauncher;
+      }
+    }
+
     // Maybe insert an include-what-you-use runner.
     if (!compileCommands.empty() && (lang == "C" || lang == "CXX")) {
       std::string const iwyu_prop = lang + "_INCLUDE_WHAT_YOU_USE";
@@ -656,6 +668,13 @@ void cmMakefileTargetGenerator::WriteObjectBuildFile(
       if ((iwyu && *iwyu) || (tidy && *tidy) || (cpplint && *cpplint) ||
           (cppcheck && *cppcheck)) {
         std::string run_iwyu = "$(CMAKE_COMMAND) -E __run_co_compile";
+        if (!compilerLauncher.empty()) {
+          // In __run_co_compile case the launcher command is supplied
+          // via --launcher=<maybe-list> and consumed
+          run_iwyu += " --launcher=";
+          run_iwyu += this->LocalGenerator->EscapeForShell(compilerLauncher);
+          compilerLauncher.clear();
+        }
         if (iwyu && *iwyu) {
           run_iwyu += " --iwyu=";
           run_iwyu += this->LocalGenerator->EscapeForShell(iwyu);
@@ -682,21 +701,15 @@ void cmMakefileTargetGenerator::WriteObjectBuildFile(
       }
     }
 
-    // Maybe insert a compiler launcher like ccache or distcc
-    if (!compileCommands.empty() && (lang == "C" || lang == "CXX" ||
-                                     lang == "Fortran" || lang == "CUDA")) {
-      std::string const clauncher_prop = lang + "_COMPILER_LAUNCHER";
-      const char* clauncher =
-        this->GeneratorTarget->GetProperty(clauncher_prop);
-      if (clauncher && *clauncher) {
-        std::vector<std::string> launcher_cmd;
-        cmSystemTools::ExpandListArgument(clauncher, launcher_cmd, true);
-        for (std::string& i : launcher_cmd) {
-          i = this->LocalGenerator->EscapeForShell(i);
-        }
-        std::string const& run_launcher = cmJoin(launcher_cmd, " ") + " ";
-        compileCommands.front().insert(0, run_launcher);
+    // If compiler launcher was specified and not consumed above, it
+    // goes to the beginning of the command line.
+    if (!compileCommands.empty() && !compilerLauncher.empty()) {
+      std::vector<std::string> args;
+      cmSystemTools::ExpandListArgument(compilerLauncher, args, true);
+      for (std::string& i : args) {
+        i = this->LocalGenerator->EscapeForShell(i);
       }
+      compileCommands.front().insert(0, cmJoin(args, " ") + " ");
     }
 
     std::string launcher;