Author: Aditya Medhane Date: 2026-07-06T22:54:28+03:00 New Revision: f348d964af441ec454e5fc12ab1b599cfc1e7d14
URL: https://github.com/llvm/llvm-project/commit/f348d964af441ec454e5fc12ab1b599cfc1e7d14 DIFF: https://github.com/llvm/llvm-project/commit/f348d964af441ec454e5fc12ab1b599cfc1e7d14.diff LOG: [Clang] Enable -Wunused-template under -Wall (#206123) Uncomment `UnusedTemplate` in the `Unused` diagnostic group so `-Wunused-template` becomes part of `-Wall`. `-Wunused-template` flags 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 (ill-formed, no diagnostic required), so enabling this surfaces a real class of bugs and keeps the pattern from reappearing. ### Depends on The in-tree occurrences were cleaned up first in a series of NFC PRs tracked by #202945. This change only builds clean once those land, so CI will be red on any area whose cleanup is not yet merged. Remaining prerequisites: Approved - #202969 - #202971 - #202973 - #202974 - #206309 - #206312 Needs to be reviewed - #202988 - #206308 Closes #202945 cc @AaronBallman @vgvassilev Added: Modified: clang/docs/ReleaseNotes.md clang/include/clang/Basic/DiagnosticGroups.td clang/test/Misc/warning-wall.c clang/test/SemaCXX/warn-func-not-needed.cpp clang/test/SemaCXX/warn-variable-not-needed.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md index 77b6f89e39f83..3ec47eb8b18c3 100644 --- a/clang/docs/ReleaseNotes.md +++ b/clang/docs/ReleaseNotes.md @@ -548,6 +548,11 @@ 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 73fb97aeeb302..79583534b9bbd 100644 --- a/clang/include/clang/Basic/DiagnosticGroups.td +++ b/clang/include/clang/Basic/DiagnosticGroups.td @@ -1369,7 +1369,7 @@ 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
