[Clang] allow restrict qualifier for array types with pointer types as element types

[a-tarasyuk]

Fixes #92847

---

Types other than pointer types whose referenced type is an object type and (possibly multi-dimensional) array types with such pointer types as element type shall not be restrict-qualified.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Oleksandr T. (a-tarasyuk)

Changes

Fixes #92847

---

> Types other than pointer types whose referenced type is an object type and (possibly multi-dimensional) array types with such pointer types as element type shall not be restrict-qualified.

---

Full diff: https://github.com/llvm/llvm-project/pull/120896.diff

3 Files Affected:

• (modified) clang/docs/ReleaseNotes.rst (+1)
• (modified) clang/lib/Sema/SemaType.cpp (+3-1)
• (modified) clang/test/Sema/types.c (+5-5)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 6b9e1109f3906e..52daea9b8eb2b6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -332,6 +332,7 @@ C Language Changes
 ------------------
 
 - Extend clang's ``<limits.h>`` to define ``LONG_LONG_*`` macros for Android's bionic.
+- Clang now allows ``restrict`` qualifier for array types with pointer elements (#GH92847).
 
 C2y Feature Support
 ^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 83464c50b4b238..e84daeee679a57 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -1595,12 +1595,14 @@ QualType Sema::BuildQualifiedType(QualType T, SourceLocation Loc,
     QualType ProblemTy;
 
     if (T->isAnyPointerType() || T->isReferenceType() ||
-        T->isMemberPointerType()) {
+        T->isMemberPointerType() || T->isArrayType()) {
       QualType EltTy;
       if (T->isObjCObjectPointerType())
         EltTy = T;
       else if (const MemberPointerType *PTy = T->getAs<MemberPointerType>())
         EltTy = PTy->getPointeeType();
+      else if (T->isArrayType())
+        EltTy = Context.getBaseElementType(T);
       else
         EltTy = T->getPointeeType();
 
diff --git a/clang/test/Sema/types.c b/clang/test/Sema/types.c
index e0a6ba4f0691b9..4c90634b7ce284 100644
--- a/clang/test/Sema/types.c
+++ b/clang/test/Sema/types.c
@@ -9,20 +9,20 @@ typedef int (*T)[2];
 restrict T x;
 
 typedef int *S[2];
-restrict S y; // expected-error {{restrict requires a pointer or reference ('S' (aka 'int *[2]') is invalid)}}
-
-
+restrict S y;
 
 // int128_t is available.
 int a(void) {
   __int128_t s;
   __uint128_t t;
-}
+} // expected-warning {{non-void function does not return a value}}
+
 // but not a keyword
 int b(void) {
   int __int128_t;
   int __uint128_t;
-}
+} // expected-warning {{non-void function does not return a value}}
+
 // __int128 is a keyword
 int c(void) {
   __int128 i;

[cor3ntin]

@AaronBallman ping

[AaronBallman]

I believe these changes are correct, but adding a few more folks interested in C to verify because existing compilers definitely disagree: https://godbolt.org/z/1Yb44WP9o

[AaronBallman]

I think this is pretty close, mostly just nits from me.

[AaronBallman]

LGTM! Please wait a bit before landing in case @efriedma-quic has any additional comments.