Preprocessor: Suppress -Wnonportable-include-path for header maps

If a file search involves a header map, suppress
-Wnonportable-include-path.  It's firing lots of false positives for
framework authors internally, and it's not trivial to fix.

Consider a framework called "Foo" with a main (installed) framework header
"Foo/Foo.h".  It's atypical for "Foo.h" to actually live inside a
directory called "Foo" in the source repository.  Instead, the
build system generates a header map while building the framework.
If Foo.h lives at the top-level of the source repository (common), and
the git repo is called ssh://some.url/foo.git, then the header map will
have something like:

    Foo/Foo.h -> /Users/myname/code/foo/Foo.h

where "/Users/myname/code/foo" is the clone of ssh://some.url/foo.git.

After #import <Foo/Foo.h>, the current implementation of
-Wnonportable-include-path will falsely assume that Foo.h was found in a
nonportable way, because of the name of the git clone (.../foo/Foo.h).
However, that directory name was not involved in the header search at
all.

This commit adds an extra parameter to Preprocessor::LookupFile and
HeaderSearch::LookupFile to track if the search used a header map,
making it easy to suppress the warning.  Longer term, once we find a way
to avoid the false positive, we should turn the warning back on.

rdar://problem/28863903

llvm-svn: 301592

3 files changed, 16 insertions, 0 deletions

diff --git a/clang/test/Preprocessor/Inputs/nonportable-hmaps/foo.hmap b/clang/test/Preprocessor/Inputs/nonportable-hmaps/foo.hmap
new file mode 100644
index 00000000000..9036f208711
--- /dev/null
+++ b/clang/test/Preprocessor/Inputs/nonportable-hmaps/foo.hmap
diff --git a/clang/test/Preprocessor/Inputs/nonportable-hmaps/headers/foo/Foo.h b/clang/test/Preprocessor/Inputs/nonportable-hmaps/headers/foo/Foo.h
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/clang/test/Preprocessor/Inputs/nonportable-hmaps/headers/foo/Foo.h
diff --git a/clang/test/Preprocessor/nonportable-include-with-hmap.c b/clang/test/Preprocessor/nonportable-include-with-hmap.c
new file mode 100644
index 00000000000..fc958e7e5e3
--- /dev/null
+++ b/clang/test/Preprocessor/nonportable-include-with-hmap.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -Eonly                        \
+// RUN:   -I%S/Inputs/nonportable-hmaps/foo.hmap \
+// RUN:   -I%S/Inputs/nonportable-hmaps          \
+// RUN:   %s -verify
+//
+// foo.hmap contains: Foo/Foo.h -> headers/foo/Foo.h
+//
+// Header search of "Foo/Foo.h" follows this path:
+//  1. Look for "Foo/Foo.h".
+//  2. Find "Foo/Foo.h" in "nonportable-hmaps/foo.hmap".
+//  3. Look for "headers/foo/Foo.h".
+//  4. Find "headers/foo/Foo.h" in "nonportable-hmaps".
+//  5. Return.
+//
+// There is nothing nonportable; -Wnonportable-include-path should not fire.
+#include "Foo/Foo.h" // expected-no-diagnostics