From: Nick Desaulniers <ndesaulniers@google.com>
Date: Thu, 12 Sep 2019 19:53:35 +0000 (+0000)
Subject: [Clang][CodeGen] support alias attribute w/ gnu_inline
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2b3c18bb4934434a5a5e16c6d7930fac282107b9;p=clang

[Clang][CodeGen] support alias attribute w/ gnu_inline

Summary:
r369705 did not consider the addition of gnu_inline on function
declarations of alias attributed functions. This resulted in a reported
regression in the clang-9-rc4 release from the Zig developers building
glibc, which was observable as a failed assertion:

llvm-project/clang/lib/AST/Decl.cpp:3336: bool
clang::FunctionDecl::isInlineDefinitionExternallyVisible() const:
Assertion `(doesThisDeclarationHaveABody() || willHaveBody()) && "Must
be a function definition"' failed.

Alias function declarations do not have bodies, so allow us to proceed
if we have the alias function attribute but no body/definition, and add
a test case.  The emitted symbols and their linkage matches GCC for the
added test case.

Link: https://bugs.llvm.org/show_bug.cgi?id=43268

Reviewers: aaron.ballman, rsmith, erichkeane, andrewrk

Reviewed By: andrewrk

Subscribers: cfe-commits, andrewrk, hans, srhines

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67455

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@371766 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 1d28f03b06..b27ac907b8 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -3348,7 +3348,8 @@ SourceRange FunctionDecl::getExceptionSpecSourceRange() const {
 /// an externally visible symbol, but "extern inline" will not create an
 /// externally visible symbol.
 bool FunctionDecl::isInlineDefinitionExternallyVisible() const {
-  assert((doesThisDeclarationHaveABody() || willHaveBody()) &&
+  assert((doesThisDeclarationHaveABody() || willHaveBody() ||
+          hasAttr<AliasAttr>()) &&
          "Must be a function definition");
   assert(isInlined() && "Function must be inline");
   ASTContext &Context = getASTContext();
diff --git a/test/CodeGen/alias.c b/test/CodeGen/alias.c
index 46568ee900..f5bdf3c058 100644
--- a/test/CodeGen/alias.c
+++ b/test/CodeGen/alias.c
@@ -99,3 +99,8 @@ static int test10_foo __attribute__((alias("test10")));
 // CHECKGLOBALS-NOT: @test11_foo = dso_local
 void test11(void) {}
 static void test11_foo(void) __attribute__((alias("test11")));
+
+// Test that gnu_inline+alias work.
+// CHECKGLOBALS: @test12_alias = alias void (), void ()* @test12
+void test12(void) {}
+inline void test12_alias(void) __attribute__((gnu_inline, alias("test12")));