[clangd] support the zig c++ compiler wrapper

[mrexodia]

When using zig c++ for cross-compiling clangd removes the zig command (c++/cc) from the command line. Because of this the system include extraction fails. This change detects that the driver executable is named zig and adds cc or c++ back into the command line.

I don't think there is infrastructure to test this (since it would involve executing the zig executable), so I did not add any tests. Screenshot of the feature working on Visual Studio Code on Windows:

Trivial example project that sets up the cross compilation with CMake and generates compile_commands.json: https://github.com/mrexodia/zig-cross. You also need to use --query-driver=**/zig.exe.

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[llvmbot]

@llvm/pr-subscribers-clangd

@llvm/pr-subscribers-clang-tools-extra

Author: Duncan Ogilvie (mrexodia)

Changes

When using zig c++ for cross-compiling clangd removes the zig command from the command line. Because of this the system include extraction fails. This change detects that the driver executable is named zig and adds cc or c++ back into the command line.

I don't think there is infrastructure to test this (since it would involve executing the zig executable), so I did not add any tests.

---

Full diff: https://github.com/llvm/llvm-project/pull/100759.diff

1 Files Affected:

• (modified) clang-tools-extra/clangd/SystemIncludeExtractor.cpp (+11-1)

diff --git a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
index d4b9b173d149d..c01dbea9c0c12 100644
--- a/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
+++ b/clang-tools-extra/clangd/SystemIncludeExtractor.cpp
@@ -389,7 +389,17 @@ extractSystemIncludesAndTarget(const DriverArgs &InputArgs,
     return std::nullopt;
   }
 
-  llvm::SmallVector<llvm::StringRef> Args = {Driver, "-E", "-v"};
+  llvm::SmallVector<llvm::StringRef> Args = {Driver};
+  // Support the zig compiler wrapper
+  auto DriverExecutable = llvm::sys::path::stem(Driver);
+  if (DriverExecutable == "zig") {
+    if (InputArgs.Lang == "c") {
+      Args.push_back("cc");
+    } else {
+      Args.push_back("c++");
+    }
+  }
+  Args.append({"-E", "-v"});
   Args.append(InputArgs.render());
   // Input needs to go after Lang flags.
   Args.push_back("-");

[duk-37]

This is a simple and nice change. Improving the developer experience and having things "just work" is always good.

[mrexodia]

@kazutakahirata @kadircet @sam-mccall it looks like you were recently touching this file, any chance for a review?

[mrexodia]

Ping!

[mrexodia]

Worked around this by creating a wrapper script zig-c++: mrexodia/zig-cross@56b384c