[llvm-config] Fix bug where `--libfiles` and `--names` would produce

incorrect output when LLVM is built with `LLVM_BUILD_LLVM_DYLIB`.

`llvm-config` previously produced output like this

```
$ llvm-config --libfiles
/usr/lib/liblibLLVM-4.0svn.so.so
$ llvm-config --libnames
liblibLLVM-4.0svn.so.so
```

The library prefix and shared library extension were added to
the library name twice which was wrong.

I wanted to write a test cases for this but it looks like **all**
`llvm-config` tests were disabled by r260386 so I'll leave this for
now.

Subscribers: llvm-commits, tstellarAMD

Reviewers: beanz, DiamondLovesYou, axw

Differential Revision: https://reviews.llvm.org/D27393

llvm-svn: 289488

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/tools/llvm-config/llvm-config.cpp b/llvm/tools/llvm-config/llvm-config.cpp
index c63733f9a8b..4b4a3ea97ab 100644
--- a/llvm/tools/llvm-config/llvm-config.cpp
+++ b/llvm/tools/llvm-config/llvm-config.cpp
@@ -432,7 +432,15 @@ int main(int argc, char **argv) {
                                          const bool Shared) {
     std::string LibFileName;
     if (Shared) {
-      LibFileName = (SharedPrefix + Lib + "." + SharedExt).str();
+      if (Lib == DyLibName) {
+        // Treat the DyLibName specially. It is not a component library and
+        // already has the necessary prefix and suffix (e.g. `.so`) added so
+        // just return it unmodified.
+        assert(Lib.endswith(SharedExt) && "DyLib is missing suffix");
+        LibFileName = Lib;
+      } else {
+        LibFileName = (SharedPrefix + Lib + "." + SharedExt).str();
+      }
     } else {
       // default to static
       LibFileName = (StaticPrefix + Lib + "." + StaticExt).str();