[clang] [clang][Sema] Subclass `-Wshorten-64-to-32` under `-Wimplicit-int-conversion` (PR #80814)

[via cfe-commits]

https://github.com/whisperity updated https://github.com/llvm/llvm-project/pull/80814

>From ac12272a655e28c1b11a8b9dbb9d37cd5299e86e Mon Sep 17 00:00:00 2001
From: Whisperity <whisperity at gmail.com>
Date: Tue, 6 Feb 2024 10:08:34 +0100
Subject: [PATCH] [clang][Sema] Subclass `-Wshorten-64-to-32` under
 `-Wimplicit-int-conversion`

---
 clang/docs/ReleaseNotes.rst                   |  7 ++++++-
 clang/include/clang/Basic/DiagnosticGroups.td |  6 +++---
 clang/test/Sema/conversion-64-32.c            |  6 +++++-
 ...onversion-implicit-int-includes-64-to-32.c | 21 +++++++++++++++++++
 4 files changed, 35 insertions(+), 5 deletions(-)
 create mode 100644 clang/test/Sema/conversion-implicit-int-includes-64-to-32.c

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3596109bf044f..1f488ae5f5af8 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -149,7 +149,12 @@ Improvements to Clang's diagnostics
   prints.
 
 - Clang now diagnoses member template declarations with multiple declarators.
-- Clang now diagnoses use of the ``template`` keyword after declarative nested name specifiers.
+
+- Clang now diagnoses use of the ``template`` keyword after declarative nested
+  name specifiers.
+
+- Added `-Wshorten-64-to-32` diagnostics to enable when
+  `-Wimplicit-int-conversion` is enabled.
 
 Improvements to Clang's time-trace
 ----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 6765721ae7002..975eca0ad9b64 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -108,8 +108,10 @@ def EnumConversion : DiagGroup<"enum-conversion",
                                 EnumCompareConditional]>;
 def ObjCSignedCharBoolImplicitIntConversion :
   DiagGroup<"objc-signed-char-bool-implicit-int-conversion">;
+def Shorten64To32 : DiagGroup<"shorten-64-to-32">;
 def ImplicitIntConversion : DiagGroup<"implicit-int-conversion",
-                                     [ObjCSignedCharBoolImplicitIntConversion]>;
+                                     [Shorten64To32,
+                                      ObjCSignedCharBoolImplicitIntConversion]>;
 def ImplicitConstIntFloatConversion : DiagGroup<"implicit-const-int-float-conversion">;
 def ImplicitIntFloatConversion : DiagGroup<"implicit-int-float-conversion",
  [ImplicitConstIntFloatConversion]>;
@@ -631,7 +633,6 @@ def Shadow : DiagGroup<"shadow", [ShadowFieldInConstructorModified,
 def ShadowAll : DiagGroup<"shadow-all", [Shadow, ShadowFieldInConstructor,
                                          ShadowUncapturedLocal, ShadowField]>;
 
-def Shorten64To32 : DiagGroup<"shorten-64-to-32">;
 def : DiagGroup<"sign-promo">;
 def SignCompare : DiagGroup<"sign-compare">;
 def SwitchDefault  : DiagGroup<"switch-default">;
@@ -942,7 +943,6 @@ def Conversion : DiagGroup<"conversion",
                             EnumConversion,
                             BitFieldEnumConversion,
                             FloatConversion,
-                            Shorten64To32,
                             IntConversion,
                             ImplicitIntConversion,
                             ImplicitFloatConversion,
diff --git a/clang/test/Sema/conversion-64-32.c b/clang/test/Sema/conversion-64-32.c
index dc417edcbc216..c172dd109f3be 100644
--- a/clang/test/Sema/conversion-64-32.c
+++ b/clang/test/Sema/conversion-64-32.c
@@ -9,9 +9,13 @@ typedef long long long2 __attribute__((__vector_size__(16)));
 
 int4 test1(long2 a) {
   int4  v127 = a;  // no warning.
-  return v127; 
+  return v127;
 }
 
 int test2(long v) {
   return v / 2; // expected-warning {{implicit conversion loses integer precision: 'long' to 'int'}}
 }
+
+char test3(short s) {
+  return s * 2; // no warning.
+}
diff --git a/clang/test/Sema/conversion-implicit-int-includes-64-to-32.c b/clang/test/Sema/conversion-implicit-int-includes-64-to-32.c
new file mode 100644
index 0000000000000..e22ccbe821f65
--- /dev/null
+++ b/clang/test/Sema/conversion-implicit-int-includes-64-to-32.c
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wimplicit-int-conversion -triple x86_64-apple-darwin %s
+
+int test0(long v) {
+  return v; // expected-warning {{implicit conversion loses integer precision}}
+}
+
+typedef int  int4  __attribute__ ((vector_size(16)));
+typedef long long long2 __attribute__((__vector_size__(16)));
+
+int4 test1(long2 a) {
+  int4  v127 = a;  // no warning.
+  return v127;
+}
+
+int test2(long v) {
+  return v / 2; // expected-warning {{implicit conversion loses integer precision: 'long' to 'int'}}
+}
+
+char test3(short s) {
+  return s * 2; // expected-warning {{implicit conversion loses integer precision: 'int' to 'char'}}
+}