[clang] Use operator<< for APSInt/APInt in array access diagnostics (PR #161474)

[Samarth Narang via cfe-commits]

https://github.com/snarang181 updated https://github.com/llvm/llvm-project/pull/161474

>From 0e21cdb94705ba053ed78bd3f9a5056bdaab61e1 Mon Sep 17 00:00:00 2001
From: Samarth Narang <snarang at umass.edu>
Date: Wed, 1 Oct 2025 09:47:41 +0530
Subject: [PATCH 1/2] Use operator<< for APSInt/APInt in array access
 diagnostics

---
 clang/lib/Sema/SemaChecking.cpp | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 39c3aa2243338..08e4a693bd556 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -14882,7 +14882,7 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
       // dependent CharUnits)
       DiagRuntimeBehavior(BaseExpr->getBeginLoc(), BaseExpr,
                           PDiag(DiagID)
-                              << toString(index, 10, true) << AddrBits
+                              << index << AddrBits
                               << (unsigned)ASTC.toBits(*ElemCharUnits)
                               << toString(ElemBytes, 10, false)
                               << toString(MaxElems, 10, false)
@@ -14970,10 +14970,10 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
     unsigned CastMsg = (!ASE || BaseType == EffectiveType) ? 0 : 1;
     QualType CastMsgTy = ASE ? ASE->getLHS()->getType() : QualType();
 
-    DiagRuntimeBehavior(
-        BaseExpr->getBeginLoc(), BaseExpr,
-        PDiag(DiagID) << toString(index, 10, true) << ArrayTy->desugar()
-                      << CastMsg << CastMsgTy << IndexExpr->getSourceRange());
+    DiagRuntimeBehavior(BaseExpr->getBeginLoc(), BaseExpr,
+                        PDiag(DiagID)
+                            << index << ArrayTy->desugar() << CastMsg
+                            << CastMsgTy << IndexExpr->getSourceRange());
   } else {
     unsigned DiagID = diag::warn_array_index_precedes_bounds;
     if (!ASE) {
@@ -14982,8 +14982,7 @@ void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
     }
 
     DiagRuntimeBehavior(BaseExpr->getBeginLoc(), BaseExpr,
-                        PDiag(DiagID) << toString(index, 10, true)
-                                      << IndexExpr->getSourceRange());
+                        PDiag(DiagID) << index << IndexExpr->getSourceRange());
   }
 
   const NamedDecl *ND = nullptr;

>From 840e875ea11f993ae38cd83a94e1d4ff1bf24660 Mon Sep 17 00:00:00 2001
From: Samarth Narang <snarang at umass.edu>
Date: Wed, 1 Oct 2025 13:45:31 +0530
Subject: [PATCH 2/2] InsertSeparator=false by default

---
 clang/test/SemaCXX/array-bounds.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/test/SemaCXX/array-bounds.cpp b/clang/test/SemaCXX/array-bounds.cpp
index b584e1e7cd453..6a40d1db0a6fd 100644
--- a/clang/test/SemaCXX/array-bounds.cpp
+++ b/clang/test/SemaCXX/array-bounds.cpp
@@ -237,7 +237,7 @@ void test_pr10771() {
     ((char*)foo)[sizeof(foo) - 1] = '\0';  // no-warning
     *(((char*)foo) + sizeof(foo) - 1) = '\0';  // no-warning
 
-    ((char*)foo)[sizeof(foo)] = '\0';  // expected-warning {{array index 32768 is past the end of the array (that has type 'double[4096]', cast to 'char *')}}
+    ((char*)foo)[sizeof(foo)] = '\0';  // expected-warning {{array index 32'768 is past the end of the array (that has type 'double[4096]', cast to 'char *')}}
 
     // TODO: This should probably warn, too.
     *(((char*)foo) + sizeof(foo)) = '\0';  // no-warning
@@ -248,7 +248,7 @@ int test_pr11007_aux(const char * restrict, ...);
 // Test checking with varargs.
 void test_pr11007() {
   double a[5]; // expected-note {{array 'a' declared here}}
-  test_pr11007_aux("foo", a[1000]); // expected-warning {{array index 1000 is past the end of the array (that has type 'double[5]')}}
+  test_pr11007_aux("foo", a[1000]); // expected-warning {{array index 1'000 is past the end of the array (that has type 'double[5]')}}
 }
 
 void test_rdar10916006(void)