[Sema] Do not show unused parameter warnings when body is skipped

Summary: Without the function body, we cannot determine is parameter was used.

Reviewers: ioeric, sammccall

Reviewed By: sammccall

Subscribers: arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D53456

llvm-svn: 345122

clang/lib/Sema/SemaDecl.cpp

@@ -13037,7 +13037,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
 
     if (!FD->isInvalidDecl()) {
       // Don't diagnose unused parameters of defaulted or deleted functions.
-      if (!FD->isDeleted() && !FD->isDefaulted())
+      if (!FD->isDeleted() && !FD->isDefaulted() && !FD->hasSkippedBody())
         DiagnoseUnusedParameters(FD->parameters());
       DiagnoseSizeOfParametersAndReturnValue(FD->parameters(),
                                              FD->getReturnType(), FD);
@@ -13132,7 +13132,8 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
     assert(MD == getCurMethodDecl() && "Method parsing confused");
     MD->setBody(Body);
     if (!MD->isInvalidDecl()) {
-      DiagnoseUnusedParameters(MD->parameters());
+      if (!MD->hasSkippedBody())
+        DiagnoseUnusedParameters(MD->parameters());
       DiagnoseSizeOfParametersAndReturnValue(MD->parameters(),
                                              MD->getReturnType(), MD);
 

clang/test/Index/skipped-bodies-unused.cpp

@@ -0,0 +1,8 @@
+// RUN: env CINDEXTEST_SKIP_FUNCTION_BODIES=1 c-index-test -test-load-source all %s -Wunused-parameter 2>&1 \
+// RUN: | FileCheck %s
+
+// No 'unused parameter' warnings should be shown when skipping the function bodies.
+inline int foo(int used, int unused) {
+    used = 100;
+}
+// CHECK-NOT: warning: unused parameter