Add -Wpoison-system-directories warning

When using clang as a cross-compiler, we should not use system
headers to do the compilation.
This CL adds support of a new warning flag -Wpoison-system-directories which
emits warnings if --sysroot is set and headers from common host system location
are used.
By default the warning is disabled.

The intention of the warning is to catch bad includes which are usually
generated by third party build system not targeting cross-compilation.
Such cases happen in Chrome OS when someone imports a new package or upgrade
one to a newer version from upstream.

Patch by: denik (Denis Nikitin)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@371785 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticCommonKinds.td b/include/clang/Basic/DiagnosticCommonKinds.td
index 8196a4601c224636ab09a03462a532cd3dc0f506..1cd62d1e138efd1718b8394f0eec1bd173d36b15 100644 (file)
--- a/include/clang/Basic/DiagnosticCommonKinds.td
+++ b/include/clang/Basic/DiagnosticCommonKinds.td
@@ -315,4 +315,9 @@ def err_unknown_analyzer_checker_or_package : Error<
     "no analyzer checkers or packages are associated with '%0'">;
 def note_suggest_disabling_all_checkers : Note<
     "use -analyzer-disable-all-checks to disable all static analyzer checkers">;
+
+// Poison system directories.
+def warn_poison_system_directories : Warning <
+  "include location '%0' is unsafe for cross-compilation">,
+  InGroup<DiagGroup<"poison-system-directories">>, DefaultIgnore;
 }

diff --git a/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
index ad0d23271487aa4a301b4dfc638cce4e5b1483c2..5d877ee9c0d739c2bd1fdc63f636d6af3895bc30 100644 (file)
--- a/lib/Frontend/InitHeaderSearch.cpp
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -137,6 +137,13 @@ bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
   SmallString<256> MappedPathStorage;
   StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
 
+  // If use system headers while cross-compiling, emit the warning.
+  if (HasSysroot && (MappedPathStr.startswith("/usr/include") ||
+                     MappedPathStr.startswith("/usr/local/include"))) {
+    Headers.getDiags().Report(diag::warn_poison_system_directories)
+        << MappedPathStr;
+  }
+
   // Compute the DirectoryLookup type.
   SrcMgr::CharacteristicKind Type;
   if (Group == Quoted || Group == Angled || Group == IndexHeaderMap) {

diff --git a/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/lib/.keep b/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/lib/.keep
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/include/c++/.keep b/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/include/c++/.keep
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/lib/gcc/.keep b/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/lib/gcc/.keep
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/local/include/.keep b/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/local/include/.keep
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/local/lib/.keep b/test/Frontend/Inputs/sysroot_x86_64_cross_linux_tree/usr/local/lib/.keep
new file mode 100644 (file)
index 0000000..e69de29

diff --git a/test/Frontend/warning-poison-system-directories.c b/test/Frontend/warning-poison-system-directories.c
new file mode 100644 (file)
index 0000000..018f02d
--- /dev/null
+++ b/test/Frontend/warning-poison-system-directories.c
@@ -0,0 +1,27 @@
+// System directory and sysroot option causes warning.
+// RUN: %clang -Wpoison-system-directories -target x86_64 -I/usr/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.1.stderr
+// RUN: FileCheck -check-prefix=WARN < %t.1.stderr %s
+// RUN: %clang -Wpoison-system-directories -target x86_64 -cxx-isystem/usr/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.1.stderr
+// RUN: FileCheck -check-prefix=WARN < %t.1.stderr %s
+// RUN: %clang -Wpoison-system-directories -target x86_64 -iquote/usr/local/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.1.stderr
+// RUN: FileCheck -check-prefix=WARN < %t.1.stderr %s
+// RUN: %clang -Wpoison-system-directories -target x86_64 -isystem/usr/local/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.1.stderr
+// RUN: FileCheck -check-prefix=WARN < %t.1.stderr %s
+
+// Missing target but included sysroot still causes the warning.
+// RUN: %clang -Wpoison-system-directories -I/usr/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.2.stderr
+// RUN: FileCheck -check-prefix=WARN < %t.2.stderr %s
+
+// With -Werror the warning causes the failure.
+// RUN: not %clang -Werror=poison-system-directories -target x86_64 -I/usr/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s 2> %t.3.stderr
+// RUN: FileCheck -check-prefix=ERROR < %t.3.stderr %s
+
+// Cros target without sysroot causes no warning.
+// RUN: %clang -Wpoison-system-directories -Werror -target x86_64 -I/usr/include -c -o - %s
+
+// By default the warning is off.
+// RUN: %clang -Werror -target x86_64 -I/usr/include --sysroot %S/Inputs/sysroot_x86_64_cross_linux_tree -c -o - %s
+
+// WARN: warning: include location {{[^ ]+}} is unsafe for cross-compilation [-Wpoison-system-directories]
+
+// ERROR: error: include location {{[^ ]+}} is unsafe for cross-compilation [-Werror,-Wpoison-system-directories]