[clang] [analyzer] Add support for consteval in ConditionBRVisitor::VisitTerminator (PR #146859)

[Imad Aldij via cfe-commits]

https://github.com/imdj updated https://github.com/llvm/llvm-project/pull/146859

>From 1077e164158965e824097542dc4c3ecc8821d6dc Mon Sep 17 00:00:00 2001
From: Imad Aldij <os at imadij.com>
Date: Thu, 3 Jul 2025 13:50:55 +0300
Subject: [PATCH 1/5] Add support for consteval if in ConditionBRVisitor

---
 clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index 3686bd4488877..d81a3f5a2858b 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -2794,6 +2794,9 @@ PathDiagnosticPieceRef ConditionBRVisitor::VisitTerminator(
   default:
     return nullptr;
   case Stmt::IfStmtClass:
+    // Handle if consteval which doesn't have a traditional condition
+    if (cast<IfStmt>(Term)->isConsteval())
+      return nullptr;
     Cond = cast<IfStmt>(Term)->getCond();
     break;
   case Stmt::ConditionalOperatorClass:

>From 27b793fcf2347d631991f9f83df7ef5787df17d6 Mon Sep 17 00:00:00 2001
From: Imad Aldij <os at imadij.com>
Date: Thu, 3 Jul 2025 15:52:35 +0300
Subject: [PATCH 2/5] add test case for consteval and ConditionBRVisitor

---
 clang/test/Analysis/consteval-if.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 clang/test/Analysis/consteval-if.cpp

diff --git a/clang/test/Analysis/consteval-if.cpp b/clang/test/Analysis/consteval-if.cpp
new file mode 100644
index 0000000000000..2ce9a69067951
--- /dev/null
+++ b/clang/test/Analysis/consteval-if.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_analyze_cc1 -std=c++23 -analyzer-checker=core -verify %s
+
+void test_consteval() {
+  if consteval {
+    int *ptr = nullptr;
+    *ptr = 42; // expected-warning{{Dereference of null pointer (loaded from variable 'ptr')}}
+  }
+}
\ No newline at end of file

>From 90a235dfff9c6eaaa47f62d542de03868154a806 Mon Sep 17 00:00:00 2001
From: Imad Aldij <mail at imadij.com>
Date: Thu, 3 Jul 2025 16:30:32 +0300
Subject: [PATCH 3/5] Update test formatting

Co-authored-by: Balazs Benics <benicsbalazs at gmail.com>
---
 clang/test/Analysis/consteval-if.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/Analysis/consteval-if.cpp b/clang/test/Analysis/consteval-if.cpp
index 2ce9a69067951..b7eae9db6a239 100644
--- a/clang/test/Analysis/consteval-if.cpp
+++ b/clang/test/Analysis/consteval-if.cpp
@@ -5,4 +5,4 @@ void test_consteval() {
     int *ptr = nullptr;
     *ptr = 42; // expected-warning{{Dereference of null pointer (loaded from variable 'ptr')}}
   }
-}
\ No newline at end of file
+}

>From d5015902c9faadffff0858c99b7b462055e48cc4 Mon Sep 17 00:00:00 2001
From: Imad Aldij <os at imadij.com>
Date: Mon, 7 Jul 2025 10:47:18 +0300
Subject: [PATCH 4/5] Improve code style

---
 clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index d81a3f5a2858b..4631e0cad5546 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -2793,12 +2793,14 @@ PathDiagnosticPieceRef ConditionBRVisitor::VisitTerminator(
   // more tricky because there are more than two branches to account for.
   default:
     return nullptr;
-  case Stmt::IfStmtClass:
-    // Handle if consteval which doesn't have a traditional condition
-    if (cast<IfStmt>(Term)->isConsteval())
+  case Stmt::IfStmtClass: {
+    const auto *IfStatement = cast<IfStmt>(Term);
+    // Handle if consteval which doesn't have a traditional condition.
+    if (IfStatement->isConsteval())
       return nullptr;
-    Cond = cast<IfStmt>(Term)->getCond();
+    Cond = IfStatement->getCond();
     break;
+  }
   case Stmt::ConditionalOperatorClass:
     Cond = cast<ConditionalOperator>(Term)->getCond();
     break;

>From 82a47298049a11d918e4e0d2a62bbd2683ce9aa1 Mon Sep 17 00:00:00 2001
From: Imad Aldij <os at imadij.com>
Date: Mon, 7 Jul 2025 10:47:23 +0300
Subject: [PATCH 5/5] Add test for not consteval

---
 clang/test/Analysis/consteval-if.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/clang/test/Analysis/consteval-if.cpp b/clang/test/Analysis/consteval-if.cpp
index b7eae9db6a239..f9caacf2949c9 100644
--- a/clang/test/Analysis/consteval-if.cpp
+++ b/clang/test/Analysis/consteval-if.cpp
@@ -6,3 +6,10 @@ void test_consteval() {
     *ptr = 42; // expected-warning{{Dereference of null pointer (loaded from variable 'ptr')}}
   }
 }
+
+void test_not_consteval() {
+  if !consteval {
+    int *ptr = nullptr;
+    *ptr = 42; // expected-warning{{Dereference of null pointer (loaded from variable 'ptr')}}
+  }
+}