Allow a new syntax in a module requires-declaration:

  requires ! feature

The purpose of this is to allow (for instance) the module map for /usr/include
to exclude <tgmath.h> and <complex.h> when building in C++ (these headers are
instead provided by the C++ standard library in this case, and the glibc C
<tgmath.h> header would otherwise try to include <complex.h>, resulting in a
module cycle).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193549 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index 5d3fd45..eccb94c 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -1359,11 +1359,11 @@
     }
 
     // Check whether this module is available.
-    StringRef Feature;
-    if (!Module->isAvailable(getLangOpts(), getTarget(), Feature)) {
+    clang::Module::Requirement Requirement;
+    if (!Module->isAvailable(getLangOpts(), getTarget(), Requirement)) {
       getDiagnostics().Report(ImportLoc, diag::err_module_unavailable)
         << Module->getFullModuleName()
-        << Feature
+        << Requirement.second << Requirement.first
         << SourceRange(Path.front().second, Path.back().second);
       LastModuleImportLoc = ImportLoc;
       LastModuleImportResult = ModuleLoadResult();