Back out my heinous hack that tricked the module generation mechanism

into using non-absolute system includes (<foo>)...

... and introduce another hack that is simultaneously more heineous
and more effective. We whitelist Clang-supplied headers that augment
or override system headers (such as float.h, stdarg.h, and
tgmath.h). For these headers, Clang does not provide a module
mapping. Instead, a system-supplied module map can refer to these
headers in a system module, and Clang will look both in its own
include directory and wherever the system-supplied module map
suggests, then adds either or both headers. The end result is that
Clang-supplied headers get merged into the system-supplied module for
the C standard library.

As a drive-by, fix up a few dependencies in the _Builtin_instrinsics
module.

llvm-svn: 149611

4 files changed, 26 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/System/usr/include/module.map b/clang/test/Modules/Inputs/System/usr/include/module.map
new file mode 100644
index 00000000000..884b59c80cd
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/module.map
@@ -0,0 +1,21 @@
+module cstd [system] {
+  // Only in compiler support directory
+  module float_constants {
+    header "float.h"
+  }
+
+  // Only in system headers directory
+  module stdio {
+    header "stdio.h"
+  }
+
+  // In both directories (compiler support version wins, does not forward)
+  module stdbool {
+    header "stdbool.h"
+  }
+
+  // In both directories (compiler support version wins, forwards)
+  module stdint {
+    header "stdint.h"
+  }
+}
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdbool.h b/clang/test/Modules/Inputs/System/usr/include/stdbool.h
new file mode 100644
index 00000000000..760d7dc48ef
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdbool.h
@@ -0,0 +1 @@
+// Testing hack: does not define bool/true/false.
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdint.h b/clang/test/Modules/Inputs/System/usr/include/stdint.h
new file mode 100644
index 00000000000..e8e50f90290
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdint.h
@@ -0,0 +1 @@
+typedef int my_awesome_nonstandard_integer_type;
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdio.h b/clang/test/Modules/Inputs/System/usr/include/stdio.h
new file mode 100644
index 00000000000..9a7b1063032
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdio.h
@@ -0,0 +1,3 @@
+typedef struct { int id; } FILE;
+int fprintf(FILE*restrict, const char* restrict format, ...);
+