Ensure that the identifier chains have the most recent declaration after module deserialization.

This commit introduces a set of related changes to ensure that the
declaration that shows up in the identifier chain after deserializing
declarations with a given identifier is, in fact, the most recent
declaration. The primary change involves waiting until after we
deserialize and wire up redeclaration chains before updating the
identifier chains. There is a minor optimization in here to avoid
recursively deserializing names as part of looking to see whether
top-level declarations for a given name exist.

A related change that became suddenly more urgent is to property
record a merged declaration when an entity first declared in the
current translation unit is later deserialized from a module (that had
not been loaded at the time of the original declaration). Since we key
off the canonical declaration (which is parsed, not from an AST file)
for emitted redeclarations, we simply record this as a merged
declaration during AST writing and let the readers merge them.

Re-fixes <rdar://problem/13189985>, presumably for good this time.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175447 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 30 insertions, 1 deletions

diff --git a/test/Modules/Inputs/redecl-merge-left.h b/test/Modules/Inputs/redecl-merge-left.h
index cf07165a26..d66b4aa780 100644
--- a/test/Modules/Inputs/redecl-merge-left.h
+++ b/test/Modules/Inputs/redecl-merge-left.h
@@ -90,3 +90,4 @@ typedef void funcptr_with_id(int id);
 
 @class DeclaredThenLoaded;
 
+void eventually_noreturn2(void);
diff --git a/test/Modules/Inputs/redecl-merge-right.h b/test/Modules/Inputs/redecl-merge-right.h
index b664ae9a72..46a16d3b13 100644
--- a/test/Modules/Inputs/redecl-merge-right.h
+++ b/test/Modules/Inputs/redecl-merge-right.h
@@ -85,3 +85,6 @@ const int one = ONE;
 @interface ClassWithDef 
 - (void)method;
 @end
+
+void eventually_noreturn(void) __attribute__((noreturn));
+void eventually_noreturn2(void) __attribute__((noreturn));
diff --git a/test/Modules/Inputs/redecl-merge-top.h b/test/Modules/Inputs/redecl-merge-top.h
index 690e6df1c9..27e71a7383 100644
--- a/test/Modules/Inputs/redecl-merge-top.h
+++ b/test/Modules/Inputs/redecl-merge-top.h
@@ -16,3 +16,5 @@ struct S2;
 struct S2;
 
 int func1(int);
+
+void eventually_noreturn(void);
diff --git a/test/Modules/redecl-merge.m b/test/Modules/redecl-merge.m
index 8937002299..e37366748d 100644
--- a/test/Modules/redecl-merge.m
+++ b/test/Modules/redecl-merge.m
@@ -1,5 +1,6 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -I %S/Inputs %s -verify -Wno-objc-root-class
+// RUN: %clang_cc1 -fmodules -Wreturn-type -fmodules-cache-path=%t -I %S/Inputs %s -verify -Wno-objc-root-class
+
 @class C2;
 @class C3;
 @class C3;
@@ -8,8 +9,28 @@ typedef struct my_struct_type *my_struct_ref;
 @protocol P4;
 @class C3;
 @class C3;
+
+int *call_eventually_noreturn(void) {
+  eventually_noreturn();
+} // expected-warning{{control reaches end of non-void function}}
+
+int *call_eventually_noreturn2(void) {
+  eventually_noreturn2();
+} // expected-warning{{control reaches end of non-void function}}
+
 @import redecl_merge_right;
 
+int *call_eventually_noreturn_again(void) {
+  eventually_noreturn();
+}
+
+int *call_eventually_noreturn2_again(void) {
+  // noreturn and non-noreturn functions have different types
+  eventually_noreturn2(); // expected-error{{call to 'eventually_noreturn2' is ambiguous}}
+  // expected-note@93{{candidate function}}
+  // expected-note@90{{candidate function}}
+}
+
 @implementation A
 - (Super*)init { return self; }
 @end
@@ -148,3 +169,5 @@ id<P3> p3;
 // Make sure we don't get conflicts with 'id'.
 funcptr_with_id fid;
 id id_global;
+
+