[clang] [clang-tools-extra] [Clang] [Sema] Make -Wreturn-type an error by default (PR #131207)

[via cfe-commits]

https://github.com/Sirraide updated https://github.com/llvm/llvm-project/pull/131207

>From bff3db4f6a7fdff572b662048f395c280a11d94b Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalmail at gmail.com>
Date: Thu, 13 Mar 2025 21:18:14 +0100
Subject: [PATCH 1/5] [Clang] [Sema] Make -Wreturn-type an error by default

---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 +-
 clang/test/Index/warning-flags.c                 | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 8e6e6e892cdd7..113e684a53c2b 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -722,7 +722,7 @@ def warn_falloff_nonvoid : Warning<
   "non-void "
   "%enum_select<FalloffFunctionKind>{%Function{function}|%Block{block}|%Lambda{lambda}|%Coroutine{coroutine}}0"
   " does not return a value%select{| in all control paths}1">,
-  InGroup<ReturnType>;
+  InGroup<ReturnType>, DefaultError;
 def err_falloff_nonvoid : Error<
   "non-void %select{function|block|lambda|coroutine}0 "
   "does not return a value%select{| in all control paths}1">;
diff --git a/clang/test/Index/warning-flags.c b/clang/test/Index/warning-flags.c
index 1694c6abab562..3229f000c4ae0 100644
--- a/clang/test/Index/warning-flags.c
+++ b/clang/test/Index/warning-flags.c
@@ -9,7 +9,7 @@ int *bar(float *f) { return f; }
 // RUN: c-index-test -test-load-source-reparse 5 all -w %s 2>&1 | FileCheck -check-prefix=NOWARNINGS %s
 // RUN: c-index-test -test-load-source all -w -O4 %s 2>&1 | FileCheck -check-prefix=NOWARNINGS %s
 
-// CHECK-BOTH-WARNINGS: warning: non-void function does not return a value
+// CHECK-BOTH-WARNINGS: error: non-void function does not return a value
 // CHECK-BOTH-WARNINGS: warning: incompatible pointer types returning 'float *' from a function with result type 'int *'
 
 // CHECK-SECOND-WARNING-NOT:non-void function does not return a value

>From a8523d15a4c790fe1fb58a6fe41da571cb11ba47 Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalmail at gmail.com>
Date: Tue, 18 Mar 2025 17:52:36 +0100
Subject: [PATCH 2/5] Fix clang-tidy warning

---
 .../test/clang-tidy/checkers/misc/unused-using-decls.cpp        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/unused-using-decls.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/unused-using-decls.cpp
index 62aa17b0b1c22..40451167c5809 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/misc/unused-using-decls.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/misc/unused-using-decls.cpp
@@ -233,7 +233,7 @@ namespace my_literals {
 
 using my_literals::operator"" _r;
 
-int foo() {
+void foo() {
   auto x2 = 123_r;
 }
 

>From f830db193424913aec7e355d39af68de8560adfb Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalmail at gmail.com>
Date: Wed, 19 Mar 2025 19:13:01 +0100
Subject: [PATCH 3/5] Add release note

---
 clang/docs/ReleaseNotes.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8989124611e66..1d81b5e191e89 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -38,6 +38,7 @@ Potentially Breaking Changes
 - Fix missing diagnostics for uses of declarations when performing typename access,
   such as when performing member access on a '[[deprecated]]' type alias.
   (#GH58547)
+- The `-Wreturn-type` warning now defaults to an error in all language modes.
 
 C/C++ Language Potentially Breaking Changes
 -------------------------------------------

>From fa52fa91f43d306ea77aee012a08686f2d6a7587 Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalmail at gmail.com>
Date: Wed, 9 Apr 2025 10:54:22 +0200
Subject: [PATCH 4/5] Fix a new test

---
 clang/test/CodeGen/RISCV/issue-129995.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/test/CodeGen/RISCV/issue-129995.cpp b/clang/test/CodeGen/RISCV/issue-129995.cpp
index 4cd60a854558e..1f0a297644f2c 100644
--- a/clang/test/CodeGen/RISCV/issue-129995.cpp
+++ b/clang/test/CodeGen/RISCV/issue-129995.cpp
@@ -13,8 +13,8 @@ class c {
 class g {
 public:
   template <class h> g(h);
-  friend g operator^(g, g) { c::f; }
-  friend g operator^=(g i, g j) { i ^ j; }
+  friend g operator^(g, g) { c::f; return g{0}; }
+  friend g operator^=(g i, g j) { i ^ j; return g{0}; }
 };
 template <typename, int> using k = g;
 template <typename l> using m = k<l, sizeof(l)>;

>From fcf702f39f5c5d631629fbad0e87e16652a19bb9 Mon Sep 17 00:00:00 2001
From: Sirraide <aeternalmail at gmail.com>
Date: Wed, 9 Apr 2025 10:58:54 +0200
Subject: [PATCH 5/5] Empty commit to restart CI