On 12/17/2015 10:47 AM, Kostya Serebryany wrote:
I am now observing this error message when building glibc with clang
(from trunk):
../include/string.h:101:28: error: cannot apply asm label to function
after its first use
libc_hidden_builtin_proto (memcpy)
(many more instances)
Do you think this is a bug in glibc code, or the error message could be
more relaxed?
Could you email me a .i copy of a failing build? That will help me
decide whether it's a bug in the error or in glibc.
On Fri, Dec 11, 2015 at 1:28 PM, Nick Lewycky via cfe-commits
<cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> wrote:
Author: nicholas
Date: Fri Dec 11 15:28:55 2015
New Revision: 255371
URL: http://llvm.org/viewvc/llvm-project?rev=255371&view=rev
Log:
Error on redeclaring with a conflicting asm label and on redeclaring
with an asm label after the first ODR-use. Detects problems like the
one in PR22830 where gcc and clang both compiled the file but with
different behaviour.
Added:
cfe/trunk/test/Sema/asm-label.c
Modified:
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
cfe/trunk/lib/Sema/SemaDecl.cpp
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=255371&r1=255370&r2=255371&view=diff
==============================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Dec 11
15:28:55 2015
@@ -4259,6 +4259,9 @@ def err_tag_definition_of_typedef : Erro
def err_conflicting_types : Error<"conflicting types for %0">;
def err_different_pass_object_size_params : Error<
"conflicting pass_object_size attributes on parameters">;
+def err_late_asm_label_name : Error<
+ "cannot apply asm label to %select{variable|function}0 after its
first use">;
+def err_different_asm_label : Error<"conflicting asm label">;
def err_nested_redefinition : Error<"nested redefinition of %0">;
def err_use_with_wrong_tag : Error<
"use of %0 with tag type that does not match previous declaration">;
Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=255371&r1=255370&r2=255371&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDecl.cpp Fri Dec 11 15:28:55 2015
@@ -2379,9 +2379,24 @@ void Sema::mergeDeclAttributes(NamedDecl
if (!Old->hasAttrs() && !New->hasAttrs())
return;
- // attributes declared post-definition are currently ignored
+ // Attributes declared post-definition are currently ignored.
checkNewAttributesAfterDef(*this, New, Old);
+ if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
+ if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
+ if (OldA->getLabel() != NewA->getLabel()) {
+ // This redeclaration changes __asm__ label.
+ Diag(New->getLocation(), diag::err_different_asm_label);
+ Diag(OldA->getLocation(), diag::note_previous_declaration);
+ }
+ } else if (Old->isUsed()) {
+ // This redeclaration adds an __asm__ label to a declaration
that has
+ // already been ODR-used.
+ Diag(New->getLocation(), diag::err_late_asm_label_name)
+ << isa<FunctionDecl>(Old) <<
New->getAttr<AsmLabelAttr>()->getRange();
+ }
+ }
+
if (!Old->hasAttrs())
return;
Added: cfe/trunk/test/Sema/asm-label.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/asm-label.c?rev=255371&view=auto
==============================================================================
--- cfe/trunk/test/Sema/asm-label.c (added)
+++ cfe/trunk/test/Sema/asm-label.c Fri Dec 11 15:28:55 2015
@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -verify %s
+
+void f();
+void f() __asm__("fish");
+void g();
+
+void f() {
+ g();
+}
+void g() __asm__("gold"); // expected-error{{cannot apply asm
label to function after its first use}}
+
+void h() __asm__("hose"); // expected-note{{previous declaration
is here}}
+void h() __asm__("hair"); // expected-error{{conflicting asm label}}
+
+int x;
+int x __asm__("xenon");
+int y;
+
+int test() { return y; }
+
+int y __asm__("yacht"); // expected-error{{cannot apply asm label
to variable after its first use}}
+
+int z __asm__("zebra"); // expected-note{{previous declaration is
here}}
+int z __asm__("zooms"); // expected-error{{conflicting asm label}}
+
+
+// No diagnostics on the following.
+void __real_readlink() __asm("readlink");
+void readlink() __asm("__protected_readlink");
+void readlink() { __real_readlink(); }
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