Note when a decl is used in AST files.

When an AST file is built based on another AST file, it can use a decl from
the fist file, and therefore mark the "isUsed" bit.  We need to note this in
the AST file so that the bit is set correctly when the second AST file is
loaded.

This patch introduces the distinction between setIsUsed() and markUsed() so
that we don't call into the ASTMutationListener callback when it wouldn't
be appropriate.

Fixes PR16635.

llvm-svn: 190016

3 files changed, 11 insertions, 1 deletions

diff --git a/clang/test/Modules/Inputs/System/usr/include/stdio.h b/clang/test/Modules/Inputs/System/usr/include/stdio.h
index 9a7b1063032..f41e09c35a4 100644
--- a/clang/test/Modules/Inputs/System/usr/include/stdio.h
+++ b/clang/test/Modules/Inputs/System/usr/include/stdio.h
@@ -1,3 +1,3 @@
 typedef struct { int id; } FILE;
 int fprintf(FILE*restrict, const char* restrict format, ...);
-
+extern FILE *__stderrp;
diff --git a/clang/test/Modules/Inputs/pch-used.h b/clang/test/Modules/Inputs/pch-used.h
new file mode 100644
index 00000000000..60e0097ea90
--- /dev/null
+++ b/clang/test/Modules/Inputs/pch-used.h
@@ -0,0 +1,2 @@
+@import cstd.stdio;
+static inline void SPXTrace() { fprintf(__stderrp, ""); }
diff --git a/clang/test/Modules/pch-used.m b/clang/test/Modules/pch-used.m
new file mode 100644
index 00000000000..56961ba404c
--- /dev/null
+++ b/clang/test/Modules/pch-used.m
@@ -0,0 +1,8 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: %clang_cc1 -x objective-c-header -emit-pch %S/Inputs/pch-used.h -o %t/pch-used.h.pch -fmodules -fmodules-cache-path=%t/cache -O0 -isystem %S/Inputs/System/usr/include
+// RUN: %clang_cc1 %s -include-pch %t/pch-used.h.pch -fmodules -fmodules-cache-path=%t/cache -O0 -isystem %S/Inputs/System/usr/include -emit-llvm -o - | FileCheck %s
+
+void f() { SPXTrace(); }
+
+// CHECK: define internal void @SPXTrace