Improve the error message when a PCH dependency is modified

Show the top-level pch file as the culprit, rather than the immediate
dependency when a pch file imports a pcm from a module. To clarify the
relationship, the pch import stack is printed as notes. The old behaviour was
misleading when a pch imported a pcm (from a module), since removing the pcm
would not fix the problem, whereas rebuilding the pch would.

llvm-svn: 199446

1 files changed, 20 insertions, 0 deletions

diff --git a/clang/test/PCH/modified-module-dependency.m b/clang/test/PCH/modified-module-dependency.m
new file mode 100644
index 00000000000..656fa345655
--- /dev/null
+++ b/clang/test/PCH/modified-module-dependency.m
@@ -0,0 +1,20 @@
+// RUN: rm -rf %t-dir
+// RUN: mkdir -p %t-dir
+// RUN: echo '@import test;' > %t-dir/prefix.h
+// RUN: echo 'void foo(void);' > %t-dir/test.h
+// RUN: cp %S/modified-module-dependency.module.map %t-dir/module.map
+
+// Precompile prefix.pch.
+// RUN: %clang_cc1 -x objective-c -I %t-dir -fmodules -fmodules-cache-path=%t-dir/cache -emit-pch %t-dir/prefix.h -o %t-dir/prefix.pch
+
+// Modify the dependency.
+// RUN: echo ' ' >> %t-dir/test.h
+
+// Run and check the diagnostics.
+// RUN: not %clang_cc1 -x objective-c -include-pch %t-dir/prefix.pch -fmodules -fmodules-cache-path=%t-dir/cache -fsyntax-only %s 2> %t-dir/log
+// RUN: FileCheck %s < %t-dir/log
+
+// CHECK: file '{{.*}}/test.h' has been modified since the precompiled header '{{.*}}prefix.pch' was built
+// CHECK: '{{.*}}/test.h' required by '{{.*}}/test.pcm'
+// CHECK: '{{.*}}/test.pcm' required by '{{.*}}/prefix.pch'
+// CHECK: please rebuild precompiled header '{{.*}}/prefix.pch'