[clang] Diagnose use of deprecated template alias #97619

premanandrao · 2024-07-03T18:36:59Z

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

Fixes #18236.

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

llvmbot · 2024-07-03T18:37:31Z

@llvm/pr-subscribers-clang

Author: None (premanandrao)

Changes

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

Full diff: https://github.com/llvm/llvm-project/pull/97619.diff

3 Files Affected:

(modified) clang/lib/Sema/SemaAvailability.cpp (+6)
(modified) clang/lib/Sema/SemaTemplate.cpp (+4)
(added) clang/test/SemaTemplate/alias-template-deprecated.cpp (+58)

diff --git a/clang/lib/Sema/SemaAvailability.cpp b/clang/lib/Sema/SemaAvailability.cpp
index df83bbfb7aac8..17566c226ec80 100644
--- a/clang/lib/Sema/SemaAvailability.cpp
+++ b/clang/lib/Sema/SemaAvailability.cpp
@@ -107,6 +107,12 @@ ShouldDiagnoseAvailabilityOfDecl(Sema &S, const NamedDecl *D,
     break;
   }
 
+  // For alias templates, get the underlying declaration.
+  if (const auto *ADecl = dyn_cast<TypeAliasTemplateDecl>(D)) {
+    D = ADecl->getTemplatedDecl();
+    Result = D->getAvailability(Message);
+  }
+
   // Forward class declarations get their attributes from their definition.
   if (const auto *IDecl = dyn_cast<ObjCInterfaceDecl>(D)) {
     if (IDecl->getDefinition()) {
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 6879a9a274b5c..0e7663b82f437 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4539,6 +4539,10 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
         *this, /*PointOfInstantiation=*/TemplateLoc,
         /*Entity=*/AliasTemplate,
         /*TemplateArgs=*/TemplateArgLists.getInnermost());
+
+    // Diagnose uses of this alias.
+    (void)DiagnoseUseOfDecl(AliasTemplate, TemplateLoc);
+
     if (Inst.isInvalid())
       return QualType();
 
diff --git a/clang/test/SemaTemplate/alias-template-deprecated.cpp b/clang/test/SemaTemplate/alias-template-deprecated.cpp
new file mode 100644
index 0000000000000..10242d7a810b0
--- /dev/null
+++ b/clang/test/SemaTemplate/alias-template-deprecated.cpp
@@ -0,0 +1,58 @@
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+//
+// This test checks that a deprecated attribute on an alias
+// template triggers a warning diagnostic when it is used.
+
+template <typename T>
+struct NoAttr {
+  void foo() {}
+};
+
+// expected-note@+2 5{{'UsingWithAttr' has been explicitly marked deprecated here}}
+template <typename T>
+using UsingWithAttr __attribute__((deprecated)) = NoAttr<T>;
+
+// expected-note@+1 {{'UsingInstWithAttr' has been explicitly marked deprecated here}}
+using UsingInstWithAttr __attribute__((deprecated)) = NoAttr<int>;
+
+// expected-note@+1 {{'TDWithAttr' has been explicitly marked deprecated here}}
+typedef NoAttr<int> TDWithAttr __attribute__((deprecated));
+
+// expected-warning@+1 {{'UsingWithAttr' is deprecated}}
+typedef UsingWithAttr<int> TDUsingWithAttr;
+
+typedef NoAttr<int> TDNoAttr;
+
+// expected-note@+1 {{'UsingTDWithAttr' has been explicitly marked deprecated here}}
+using UsingTDWithAttr __attribute__((deprecated)) = TDNoAttr;
+
+struct S {
+  NoAttr<float> f1;
+  // expected-warning@+1 {{'UsingWithAttr' is deprecated}}
+  UsingWithAttr<float> f2;
+};
+
+// expected-warning@+1 {{'UsingWithAttr' is deprecated}}
+void foo(NoAttr<short> s1, UsingWithAttr<short> s2) {
+}
+
+void bar() {
+  NoAttr<int> obj; // Okay
+
+  // expected-warning@+2 {{'UsingWithAttr' is deprecated}}
+  // expected-note@+1 {{in instantiation of template type alias 'UsingWithAttr' requested here}}
+  UsingWithAttr<int> objUsingWA;
+
+  // expected-warning@+2 {{'UsingWithAttr' is deprecated}}
+  // expected-note@+1 {{in instantiation of template type alias 'UsingWithAttr' requested here}}
+  UsingWithAttr<int>().foo();
+
+  // expected-warning@+1 {{'UsingInstWithAttr' is deprecated}}
+  UsingInstWithAttr objUIWA;
+
+  // expected-warning@+1 {{'TDWithAttr' is deprecated}}
+  TDWithAttr objTDWA;
+
+  // expected-warning@+1 {{'UsingTDWithAttr' is deprecated}}
+  UsingTDWithAttr objUTDWA;
+}

mizvekov · 2024-07-03T19:20:50Z

For reference, see https://reviews.llvm.org/D136533 for similar expansion of diagnostics for uses of declarations, and how that lead to trouble in MacOS land.

I'd suggest building libc++ on MacOS, to be sure this won't cause regressions and a future revert.

I have a MacOS machine now, so I should be able to try to revive that patch at some point as well.

premanandrao · 2024-07-03T19:32:59Z

For reference, see https://reviews.llvm.org/D136533 for similar expansion of diagnostics for uses of declarations, and how that lead to trouble in MacOS land.
I'd suggest building libc++ on MacOS, to be sure this won't cause regressions and a future revert.

Thanks for pointing out the other PR. I don't have a MacOS system handy right now, but I can get to one after the weekend.

I have a MacOS machine now, so I should be able to try to revive that patch at some point as well.

Sounds good.

cor3ntin · 2024-07-12T11:25:17Z

@ldionne

ldionne · 2024-07-12T20:50:30Z

I just ran the bootstrapping build with this patch applied and ran check-runtimes, and nothing failed. This might not be sufficient (perhaps I missed something important), but at first glance it doesn't seem to break anything on our side.

premanandrao · 2024-07-12T21:01:52Z

I just ran the bootstrapping build with this patch applied and ran check-runtimes, and nothing failed. This might not be sufficient (perhaps I missed something important), but at first glance it doesn't seem to break anything on our side

Thank you SO much!

Would you mind sharing (pointers to) instructions on how you built this? I was running into errors about __remove_cv_t (and others) at my end; this was without any of my changes, so it was a sort of a reference build I was trying.

ldionne · 2024-07-16T14:03:59Z

@premanandrao There are instructions here: https://libcxx.llvm.org/BuildingLibcxx.html#bootstrapping-build

You can also use e.g. run-buildbot for this job:

llvm-project/libcxx/utils/ci/run-buildbot

Line 366 in c796153

bootstrapping-build)

You will probably need to modify a few things like maybe remove the mentions of ccache.

tahonermann · 2024-07-16T15:04:22Z

clang/test/SemaTemplate/alias-template-deprecated.cpp

+
+// expected-note@+2 5{{'UsingWithAttr' has been explicitly marked deprecated here}}
+template <typename T>
+using UsingWithAttr __attribute__((deprecated)) = NoAttr<T>;


I recommend adding a test that uses the C++11 [[deprecated]] attribute syntax.

Thank you @tahonermann! Done.

AaronBallman

Thank you for this, the changes should also come with a release note in clang/docs/ReleaseNotes.rst so users know about the improvement. Changes generally LG, but I did have some test suggestions.

AaronBallman · 2024-07-18T11:19:56Z

clang/test/SemaTemplate/alias-template-deprecated.cpp

+  UsingWithCPPAttr<int> objUsingWCPPA;
+
+  // expected-warning@+1 {{'UsingInstWithCPPAttr' is deprecated: Do not use this}}
+  UsingInstWithCPPAttr objUICPPWA;


Some more test cases I'd like to see:

NoAttr<UsingWithAttr<int>> s; // diag using Foo [[deprecated]] = int; using X = UsingWithAttr<Foo>; // two diagnostics, one for Foo and one for UsingWithAttr

Thank you @AaronBallman! Added your test cases and added a release note.

AaronBallman

LGTM!

mizvekov

LGTM as well.

llvm/llvm-project#97619 makes this trigger -Wdeprecated-declarations, so this is causing Chrome's ToT bots to blow up. Bug: chromium:354996246 Change-Id: I9521c0e1e0f66d7456d8a6aa397cd9bb8c7c48ef Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5734993 Reviewed-by: Nico Hartmann <[email protected]> Commit-Queue: Nico Hartmann <[email protected]> Auto-Submit: Alan Zhao <[email protected]> Reviewed-by: Michael Lippautz <[email protected]> Cr-Commit-Position: refs/heads/main@{#95205}

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

[clang] Diagnose use of deprecated template alias

e107694

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

llvmbot added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" labels Jul 3, 2024

tahonermann reviewed Jul 16, 2024

View reviewed changes

Address CR comments: add case with c++ attribute syntax

edfde66

AaronBallman reviewed Jul 18, 2024

View reviewed changes

premanandrao added 2 commits July 18, 2024 11:42

Address more code-review comments about test coverage

cefe33e

Add a release note

786cdbf

AaronBallman approved these changes Jul 19, 2024

View reviewed changes

Merge branch 'main' into alias_template

c8e424b

mizvekov approved these changes Jul 19, 2024

View reviewed changes

AaronBallman merged commit d8e0b0d into llvm:main Jul 22, 2024
8 checks passed

yuxuanchen1997 pushed a commit that referenced this pull request Jul 25, 2024

[clang] Diagnose use of deprecated template alias (#97619)

22aa28c

Issue a warning diagnostic when a template alias with a deprecated attribute is used.

gruenich mentioned this pull request Jan 21, 2025

Support attribute deprecated for template alias #18236

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

[clang] Diagnose use of deprecated template alias #97619

[clang] Diagnose use of deprecated template alias #97619

Uh oh!

premanandrao commented Jul 3, 2024 •

edited by frederick-vs-ja

Loading

Uh oh!

llvmbot commented Jul 3, 2024

Uh oh!

mizvekov commented Jul 3, 2024

Uh oh!

premanandrao commented Jul 3, 2024

Uh oh!

cor3ntin commented Jul 12, 2024

Uh oh!

ldionne commented Jul 12, 2024

Uh oh!

premanandrao commented Jul 12, 2024 •

edited

Loading

Uh oh!

ldionne commented Jul 16, 2024

Uh oh!

tahonermann Jul 16, 2024

Uh oh!

premanandrao Jul 16, 2024

Uh oh!

AaronBallman left a comment

Uh oh!

AaronBallman Jul 18, 2024

Uh oh!

premanandrao Jul 18, 2024

Uh oh!

AaronBallman left a comment

Uh oh!

mizvekov left a comment

Uh oh!

Uh oh!

Uh oh!

[clang] Diagnose use of deprecated template alias #97619

[clang] Diagnose use of deprecated template alias #97619

Uh oh!

Conversation

premanandrao commented Jul 3, 2024 • edited by frederick-vs-ja Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

llvmbot commented Jul 3, 2024

Uh oh!

mizvekov commented Jul 3, 2024

Uh oh!

premanandrao commented Jul 3, 2024

Uh oh!

cor3ntin commented Jul 12, 2024

Uh oh!

ldionne commented Jul 12, 2024

Uh oh!

premanandrao commented Jul 12, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ldionne commented Jul 16, 2024

Uh oh!

tahonermann Jul 16, 2024

Choose a reason for hiding this comment

Uh oh!

premanandrao Jul 16, 2024

Choose a reason for hiding this comment

Uh oh!

AaronBallman left a comment

Choose a reason for hiding this comment

Uh oh!

AaronBallman Jul 18, 2024

Choose a reason for hiding this comment

Uh oh!

premanandrao Jul 18, 2024

Choose a reason for hiding this comment

Uh oh!

AaronBallman left a comment

Choose a reason for hiding this comment

Uh oh!

mizvekov left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

premanandrao commented Jul 3, 2024 •

edited by frederick-vs-ja

Loading

premanandrao commented Jul 12, 2024 •

edited

Loading