https://github.com/flash1729 updated https://github.com/llvm/llvm-project/pull/206123
>From db97aa6a8937c0b203a19258ff59e0c3039d56e4 Mon Sep 17 00:00:00 2001 From: flash1729 <[email protected]> Date: Fri, 26 Jun 2026 21:40:49 +0530 Subject: [PATCH] [Clang] Enable -Wunused-template under -Wall Uncomment UnusedTemplate in the Unused diagnostic group so -Wunused-template is part of -Wall. It diagnoses unused function and variable templates with internal linkage; in a header, such a template gives every translation unit its own internal-linkage copy, which is a latent ODR violation. Also update the affected tests (Misc/warning-wall.c and the warn-func-not-needed.cpp / warn-variable-not-needed.cpp -verify tests) and add a release note. Closes #202945. --- clang/docs/ReleaseNotes.md | 5 +++++ clang/include/clang/Basic/DiagnosticGroups.td | 2 +- clang/test/Misc/warning-wall.c | 2 ++ clang/test/SemaCXX/warn-func-not-needed.cpp | 2 +- clang/test/SemaCXX/warn-variable-not-needed.cpp | 2 +- 5 files changed, 10 insertions(+), 3 deletions(-) diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index 3e6c10666ca16..1bd0838435e42 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -543,6 +543,11 @@ latest release, please see the [Clang Web Site](https://clang.llvm.org) or the allowing it to be disabled independently with `-Wno-unused-but-set-global`. (#GH148361) +- `-Wunused-template` is now part of `-Wunused` (which is enabled by `-Wall`). + It diagnoses unused function and variable templates with internal linkage, + which in a header is a latent ODR hazard. It can be disabled with + `-Wno-unused-template`. (#GH202945) + - Added `-Wlifetime-safety` to enable lifetime safety analysis, a CFG-based intra-procedural analysis that detects use-after-free and related temporal safety bugs. See the diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td index 1c9d021317289..9ed4a75fb8d4d 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -1366,7 +1366,7 @@ def Conversion def Unused : DiagGroup<"unused", [UnusedArgument, UnusedFunction, UnusedLabel, // UnusedParameter, (matches GCC's behavior) - // UnusedTemplate, (clean-up libc++ before enabling) + UnusedTemplate, // UnusedMemberFunction, (clean-up llvm before enabling) UnusedPrivateField, UnusedLambdaCapture, UnusedLocalTypedef, UnusedValue, UnusedVariable, diff --git a/clang/test/Misc/warning-wall.c b/clang/test/Misc/warning-wall.c index 6d6c4e562400f..ade9cbaace77e 100644 --- a/clang/test/Misc/warning-wall.c +++ b/clang/test/Misc/warning-wall.c @@ -73,6 +73,8 @@ CHECK-NEXT: -Wunused-argument CHECK-NEXT: -Wunused-function CHECK-NEXT: -Wunneeded-internal-declaration CHECK-NEXT: -Wunused-label +CHECK-NEXT: -Wunused-template +CHECK-NEXT: -Wunneeded-internal-declaration CHECK-NEXT: -Wunused-private-field CHECK-NEXT: -Wunused-lambda-capture CHECK-NEXT: -Wunused-local-typedef diff --git a/clang/test/SemaCXX/warn-func-not-needed.cpp b/clang/test/SemaCXX/warn-func-not-needed.cpp index cb3cae4cd6c76..74438543c43b7 100644 --- a/clang/test/SemaCXX/warn-func-not-needed.cpp +++ b/clang/test/SemaCXX/warn-func-not-needed.cpp @@ -10,7 +10,7 @@ void foo() { } namespace test1_template { -template <typename T> static void f() {} +template <typename T> static void f() {} // expected-warning {{unused function template}} template <> void f<int>() {} // expected-warning {{function 'f<int>' is not needed and will not be emitted}} template <typename T> void foo() { diff --git a/clang/test/SemaCXX/warn-variable-not-needed.cpp b/clang/test/SemaCXX/warn-variable-not-needed.cpp index 272c8998d15c0..d234e9140e3fd 100644 --- a/clang/test/SemaCXX/warn-variable-not-needed.cpp +++ b/clang/test/SemaCXX/warn-variable-not-needed.cpp @@ -4,7 +4,7 @@ namespace test1 { static int abc = 42; // expected-warning {{variable 'abc' is not needed and will not be emitted}} namespace { - template <typename T> int abc_template = 0; + template <typename T> int abc_template = 0; // expected-warning {{unused variable template}} template <> int abc_template<int> = 0; // expected-warning {{variable 'abc_template<int>' is not needed and will not be emitted}} } // namespace template <typename T> _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
