[clang] ee57212 - [C++20] [Modules] Use '-' as the separator of partitions when searching

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2022-03-31T11:21:58+08:00
New Revision: ee572129ae15bc15e34fcae63643d6998352dab3

URL: https://github.com/llvm/llvm-project/commit/ee572129ae15bc15e34fcae63643d6998352dab3
DIFF: https://github.com/llvm/llvm-project/commit/ee572129ae15bc15e34fcae63643d6998352dab3.diff

LOG: [C++20] [Modules] Use '-' as the separator of partitions when searching
in filesystems

It is simpler to search for module unit by -fprebuilt-module-path
option. However, the separator ':' of partitions is not friendly.
According to the discussion in https://reviews.llvm.org/D118586, I think
we get consensus to use '-' as the separator instead. The '-' is the
choice of GCC too.

Previously I thought it would be better to add an option. But I feel it
is over-engineering now. Another reason here is that there are too many
options for modules (for clang module mainly) now. Given it is not bad
to use '-' when searching, I think it is acceptable to not add an
option.

Reviewed By: iains

Differential Revision: https://reviews.llvm.org/D120874

Added: 
    clang/test/Modules/search-partitions.cpp

Modified: 
    clang/lib/Lex/HeaderSearch.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 082e62da124f1..d16b9a52bff63 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -194,10 +194,19 @@ std::string HeaderSearch::getPrebuiltModuleFileName(StringRef ModuleName,
   for (const std::string &Dir : HSOpts->PrebuiltModulePaths) {
     SmallString<256> Result(Dir);
     llvm::sys::fs::make_absolute(Result);
-    llvm::sys::path::append(Result, ModuleName + ".pcm");
+    if (ModuleName.contains(':'))
+      // The separator of C++20 modules partitions (':') is not good for file
+      // systems, here clang and gcc choose '-' by default since it is not a
+      // valid character of C++ indentifiers. So we could avoid conflicts.
+      llvm::sys::path::append(Result, ModuleName.split(':').first + "-" +
+                                          ModuleName.split(':').second +
+                                          ".pcm");
+    else
+      llvm::sys::path::append(Result, ModuleName + ".pcm");
     if (getFileMgr().getFile(Result.str()))
       return std::string(Result);
   }
+
   return {};
 }
 

diff  --git a/clang/test/Modules/search-partitions.cpp b/clang/test/Modules/search-partitions.cpp
new file mode 100644
index 0000000000000..571160def7e9b
--- /dev/null
+++ b/clang/test/Modules/search-partitions.cpp
@@ -0,0 +1,44 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/partition1.cpp \
+// RUN:  -o %t/A-Part1.pcm
+
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/partition2.cpp \
+// RUN:  -o %t/A-Part2.pcm
+
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/partition3.cpp \
+// RUN:  -o %t/A-Part3.pcm
+
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/moduleA.cpp \
+// RUN:  -fprebuilt-module-path=%t
+
+// expected-no-diagnostics
+
+//--- partition1.cpp
+export module A:Part1;
+
+int part1();
+
+//--- partition2.cpp
+
+export module A:Part2;
+
+int part2();
+
+//--- partition3.cpp
+
+export module A:Part3;
+
+int part3();
+
+//--- moduleA.cpp
+
+export module A;
+
+import :Part1;
+export import :Part2;
+import :Part3;
+
+int foo();