[clang] Reland Print library module manifest path again (PR #84881)

via cfe-commits cfe-commits at lists.llvm.org
Tue Mar 12 00:29:47 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-modules

Author: Chuanqi Xu (ChuanqiXu9)

<details>
<summary>Changes</summary>

Following of https://github.com/llvm/llvm-project/pull/82160

The reason why the above PR fails is that the `--sysroot` has lower priority than the libc++ built from the same source. On the one hand, it matches the codes behavior. We will add the built libc++ project paths in the ToolChain class. But we will only add the path related to sysroot in Linux class, which is derived from the ToolChain classes. So the paths of just built libc++ is in the front of the paths relative to sysroot. On the other hand, the behavior should be good from the higher level.  Since the just built libc++ has the same version number with the just built clang, so it makes sense that these 2 compilers just matches.

So for patch it self, I hacked it by using resource dir in the test since the resource dir has the higher priority, which is not strongly correct since we won't do that in practice.

@<!-- -->kaz7 would you like to test on your environment to avoid this get reverted again?

On the libc++ side, it shows that it lacks a `modules.json` file for the just built libc++ directory. If we don't have that, it will be problematic to use std modules from the just built clang and libc++ pair. Then it is not good. And I feel it may be problematic for future compiler/standard library developers. So I feel this is somewhat  a libc++ issue that need to be fixed.

Also if we don't like the hacked test in the current patch, we must wait for libc++ to fix this to proceed. But I feel this is somewhat odd since the test of clang shouldn't dependent on libc++.

CC: @<!-- -->mordante 

---
Full diff: https://github.com/llvm/llvm-project/pull/84881.diff


4 Files Affected:

- (modified) clang/include/clang/Driver/Driver.h (+10) 
- (modified) clang/include/clang/Driver/Options.td (+3) 
- (modified) clang/lib/Driver/Driver.cpp (+44) 
- (added) clang/test/Driver/modules-print-library-module-manifest-path.cpp (+36) 


``````````diff
diff --git a/clang/include/clang/Driver/Driver.h b/clang/include/clang/Driver/Driver.h
index c4cab360bab3bb..bcf8c1295f2ddf 100644
--- a/clang/include/clang/Driver/Driver.h
+++ b/clang/include/clang/Driver/Driver.h
@@ -615,6 +615,16 @@ class Driver {
   // FIXME: This should be in CompilationInfo.
   std::string GetProgramPath(StringRef Name, const ToolChain &TC) const;
 
+  /// Lookup the path to the Standard library module manifest.
+  ///
+  /// \param C - The compilation.
+  /// \param TC - The tool chain for additional information on
+  /// directories to search.
+  //
+  // FIXME: This should be in CompilationInfo.
+  std::string GetStdModuleManifestPath(const Compilation &C,
+                                       const ToolChain &TC) const;
+
   /// HandleAutocompletions - Handle --autocomplete by searching and printing
   /// possible flags, descriptions, and its arguments.
   void HandleAutocompletions(StringRef PassedFlags) const;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index aca8c9b0d5487a..6e7f142789c994 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5374,6 +5374,9 @@ def print_resource_dir : Flag<["-", "--"], "print-resource-dir">,
 def print_search_dirs : Flag<["-", "--"], "print-search-dirs">,
   HelpText<"Print the paths used for finding libraries and programs">,
   Visibility<[ClangOption, CLOption]>;
+def print_std_module_manifest_path : Flag<["-", "--"], "print-library-module-manifest-path">,
+  HelpText<"Print the path for the C++ Standard library module manifest">,
+  Visibility<[ClangOption, CLOption]>;
 def print_targets : Flag<["-", "--"], "print-targets">,
   HelpText<"Print the registered targets">,
   Visibility<[ClangOption, CLOption]>;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 190782a79a2456..eae27769b73ec0 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -2196,6 +2196,12 @@ bool Driver::HandleImmediateArgs(const Compilation &C) {
     return false;
   }
 
+  if (C.getArgs().hasArg(options::OPT_print_std_module_manifest_path)) {
+    llvm::outs() << GetStdModuleManifestPath(C, C.getDefaultToolChain())
+                 << '\n';
+    return false;
+  }
+
   if (C.getArgs().hasArg(options::OPT_print_runtime_dir)) {
     if (std::optional<std::string> RuntimePath = TC.getRuntimePath())
       llvm::outs() << *RuntimePath << '\n';
@@ -6185,6 +6191,44 @@ std::string Driver::GetProgramPath(StringRef Name, const ToolChain &TC) const {
   return std::string(Name);
 }
 
+std::string Driver::GetStdModuleManifestPath(const Compilation &C,
+                                             const ToolChain &TC) const {
+  std::string error = "<NOT PRESENT>";
+
+  switch (TC.GetCXXStdlibType(C.getArgs())) {
+  case ToolChain::CST_Libcxx: {
+    std::string lib = GetFilePath("libc++.so", TC);
+
+    // Note when there are multiple flavours of libc++ the module json needs to
+    // look at the command-line arguments for the proper json.
+    // These flavours do not exist at the moment, but there are plans to
+    // provide a variant that is built with sanitizer instrumentation enabled.
+
+    // For example
+    //  StringRef modules = [&] {
+    //    const SanitizerArgs &Sanitize = TC.getSanitizerArgs(C.getArgs());
+    //    if (Sanitize.needsAsanRt())
+    //      return "modules-asan.json";
+    //    return "modules.json";
+    //  }();
+
+    SmallString<128> path(lib.begin(), lib.end());
+    llvm::sys::path::remove_filename(path);
+    llvm::sys::path::append(path, "modules.json");
+    if (TC.getVFS().exists(path))
+      return static_cast<std::string>(path);
+
+    return error;
+  }
+
+  case ToolChain::CST_Libstdcxx:
+    // libstdc++ does not provide Standard library modules yet.
+    return error;
+  }
+
+  return error;
+}
+
 std::string Driver::GetTemporaryPath(StringRef Prefix, StringRef Suffix) const {
   SmallString<128> Path;
   std::error_code EC = llvm::sys::fs::createTemporaryFile(Prefix, Suffix, Path);
diff --git a/clang/test/Driver/modules-print-library-module-manifest-path.cpp b/clang/test/Driver/modules-print-library-module-manifest-path.cpp
new file mode 100644
index 00000000000000..24797002b80f53
--- /dev/null
+++ b/clang/test/Driver/modules-print-library-module-manifest-path.cpp
@@ -0,0 +1,36 @@
+// Test that -print-library-module-manifest-path finds the correct file.
+
+// RUN: rm -rf %t && split-file %s %t && cd %t
+// RUN: mkdir -p %t/Inputs/usr/lib/x86_64-linux-gnu
+// RUN: touch %t/Inputs/usr/lib/x86_64-linux-gnu/libc++.so
+
+// RUN: %clang -print-library-module-manifest-path \
+// RUN:     -stdlib=libc++ \
+// RUN:     -resource-dir=%t/Inputs/usr/lib/x86_64-linux-gnu \
+// RUN:     --target=x86_64-linux-gnu 2>&1 \
+// RUN:   | FileCheck libcxx-no-module-json.cpp
+
+// RUN: touch %t/Inputs/usr/lib/x86_64-linux-gnu/modules.json
+// RUN: %clang -print-library-module-manifest-path \
+// RUN:     -stdlib=libc++ \
+// RUN:     -resource-dir=%t/Inputs/usr/lib/x86_64-linux-gnu \
+// RUN:     --target=x86_64-linux-gnu 2>&1 \
+// RUN:   | FileCheck libcxx.cpp
+
+// RUN: %clang -print-library-module-manifest-path \
+// RUN:     -stdlib=libstdc++ \
+// RUN:     -resource-dir=%t/Inputs/usr/lib/x86_64-linux-gnu \
+// RUN:     --target=x86_64-linux-gnu 2>&1 \
+// RUN:   | FileCheck libstdcxx.cpp
+
+//--- libcxx-no-module-json.cpp
+
+// CHECK: <NOT PRESENT>
+
+//--- libcxx.cpp
+
+// CHECK: {{.*}}/Inputs/usr/lib/x86_64-linux-gnu{{/|\\}}modules.json
+
+//--- libstdcxx.cpp
+
+// CHECK: <NOT PRESENT>

``````````

</details>


https://github.com/llvm/llvm-project/pull/84881


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