nunoplopes · Oct 8, 2026 · Oct 7, 2026 · Oct 7, 2026
diff --git a/cpp2rust/converter/converter.cpp b/cpp2rust/converter/converter.cpp
@@ -1382,13 +1382,15 @@ bool Converter::VisitIfStmt(clang::IfStmt *stmt) {
     stmt->setInit(init);
     return false;
   }
-  StrCat(keyword::kIf);
-  if (auto *cond = clang::dyn_cast<clang::ConstantExpr>(stmt->getCond());
-      cond && stmt->isConstexpr()) {
-    StrCat(cond->getResultAsAPSInt() != 0 ? keyword::kTrue : keyword::kFalse);
-  } else {
-    ConvertCondition(stmt->getCond());
+  if (bool taken = false;
+      !stmt->getConditionVariable() && !stmt->isConsteval() &&
+      !stmt->getCond()->isValueDependent() &&
+      stmt->getCond()->EvaluateAsBooleanCondition(taken, ctx_)) {
+    ConvertBody(taken ? stmt->getThen() : stmt->getElse());
+    return false;
   }
+  StrCat(keyword::kIf);
+  ConvertCondition(stmt->getCond());
   ConvertBody(stmt->getThen());
   if (stmt->hasElseStorage()) {
     StrCat(keyword::kElse);

diff --git a/tests/unit/if_constexpr.cpp b/tests/unit/if_constexpr.cpp
@@ -18,11 +18,22 @@ int keep_both(int x) {
   }
 }
 
+template <typename T> unsigned long long widen(T v) {
+  if (sizeof(T) > 4) {
+    T hi = v;
+    hi <<= 32;
+    return hi;
+  }
+  return v;
+}
+
 int main() {
   int v = 7;
   assert(classify(&v) == 7);
   assert(classify(1L) == 2);
   assert(classify(1) == 1);
   assert(keep_both(1) == 2);
+  assert(widen(1u) == 1);
+  assert(widen(1ull) == 4294967296ull);
   return 0;
 }
diff --git a/tests/unit/out/refcount/concepts.rs b/tests/unit/out/refcount/concepts.rs
@@ -27,21 +27,17 @@ pub fn has_size_3() -> bool {
     return false;
 }
 pub fn pick_4(mut x: i32) -> i32 {
-    if (true) && (true) {
+    {
         return 1;
     }
     return 2;
 }
 pub fn pick_5(mut x: i64) -> i32 {
-    if (true) && (false) {
-        return 1;
-    }
+    {}
     return 2;
 }
 pub fn pick_6(mut x: f32) -> i32 {
-    if (false) && (true) {
-        return 1;
-    }
+    {}
     return 2;
 }
 pub fn main() {

diff --git a/tests/unit/out/refcount/constexpr_function.rs b/tests/unit/out/refcount/constexpr_function.rs
@@ -37,9 +37,7 @@ pub fn checked_5(mut x: i32) -> i32 {
     return (x + 1);
 }
 pub fn in_constant_context_6() -> bool {
-    if false {
-        return true;
-    }
+    {}
     return (({ runtime_only_0(1) }) == 0);
 }
 const _: () = assert!(true, "in_constant_context()");

diff --git a/tests/unit/out/refcount/if_constexpr.rs b/tests/unit/out/refcount/if_constexpr.rs
@@ -7,33 +7,43 @@ use std::io::{Read, Seek, Write};
 use std::os::fd::AsFd;
 use std::rc::{Rc, Weak};
 pub fn classify_0(mut x: Ptr<i32>) -> i32 {
-    if true {
+    {
         return (x.read());
-    } else {
     }
     return 1;
 }
 pub fn classify_1(mut x: i64) -> i32 {
-    if false {
-    } else if true {
-        return 2;
+    {
+        {
+            return 2;
+        }
     }
     return 1;
 }
 pub fn classify_2(mut x: i32) -> i32 {
-    if false {
-    } else if false {
+    {
+        {}
     }
     return 1;
 }
 pub fn keep_both_3(mut x: i32) -> i32 {
-    if true {
+    {
         return (x + 1);
-    } else {
-        return (x - 1);
     }
     panic!("ub: non-void function does not return a value")
 }
+pub fn widen_4(mut v: u32) -> u64 {
+    {}
+    return (v as u64);
+}
+pub fn widen_5(mut v: u64) -> u64 {
+    {
+        let mut hi: u64 = v;
+        hi <<= 32;
+        return hi;
+    }
+    return v;
+}
 pub fn main() {
     __cpp2rust_init_globals();
     std::process::exit(main_0());
@@ -44,6 +54,8 @@ fn main_0() -> i32 {
     assert!((({ classify_1(1_i64,) }) == 2));
     assert!((({ classify_2(1,) }) == 1));
     assert!((({ keep_both_3(1,) }) == 2));
+    assert!((({ widen_4(1_u32,) }) == 1_u64));
+    assert!((({ widen_5(1_u64,) }) == 4294967296_u64));
     return 0;
 }
 pub fn __cpp2rust_init_globals() {}
diff --git a/tests/unit/out/unsafe/concepts.rs b/tests/unit/out/unsafe/concepts.rs
@@ -32,21 +32,17 @@ pub unsafe fn has_size_3() -> bool {
     return false;
 }
 pub unsafe fn pick_4(mut x: i32) -> i32 {
-    if (true) && (true) {
+    {
         return 1;
     }
     return 2;
 }
 pub unsafe fn pick_5(mut x: i64) -> i32 {
-    if (true) && (false) {
-        return 1;
-    }
+    {}
     return 2;
 }
 pub unsafe fn pick_6(mut x: f32) -> i32 {
-    if (false) && (true) {
-        return 1;
-    }
+    {}
     return 2;
 }
 pub fn main() {

diff --git a/tests/unit/out/unsafe/constexpr_function.rs b/tests/unit/out/unsafe/constexpr_function.rs
@@ -40,9 +40,7 @@ pub unsafe fn checked_5(mut x: i32) -> i32 {
     return ((x) + (1));
 }
 pub unsafe fn in_constant_context_6() -> bool {
-    if false {
-        return true;
-    }
+    {}
     return ((unsafe { runtime_only_0(1) }) == (0));
 }
 const _: () = assert!(true, "in_constant_context()");

diff --git a/tests/unit/out/unsafe/if_constexpr.rs b/tests/unit/out/unsafe/if_constexpr.rs
@@ -7,33 +7,43 @@ use std::io::{Read, Seek, Write};
 use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
 use std::rc::Rc;
 pub unsafe fn classify_0(mut x: *mut i32) -> i32 {
-    if true {
+    {
         return (*x);
-    } else {
     }
     return 1;
 }
 pub unsafe fn classify_1(mut x: i64) -> i32 {
-    if false {
-    } else if true {
-        return 2;
+    {
+        {
+            return 2;
+        }
     }
     return 1;
 }
 pub unsafe fn classify_2(mut x: i32) -> i32 {
-    if false {
-    } else if false {
+    {
+        {}
     }
     return 1;
 }
 pub unsafe fn keep_both_3(mut x: i32) -> i32 {
-    if true {
+    {
         return ((x) + (1));
-    } else {
-        return ((x) - (1));
     }
     panic!("ub: non-void function does not return a value")
 }
+pub unsafe fn widen_4(mut v: u32) -> u64 {
+    {}
+    return (v as u64);
+}
+pub unsafe fn widen_5(mut v: u64) -> u64 {
+    {
+        let mut hi: u64 = v;
+        hi <<= 32;
+        return hi;
+    }
+    return v;
+}
 pub fn main() {
     unsafe {
         __cpp2rust_init_globals();
@@ -46,6 +56,8 @@ unsafe fn main_0() -> i32 {
     assert!(((unsafe { classify_1(1_i64,) }) == (2)));
     assert!(((unsafe { classify_2(1,) }) == (1)));
     assert!(((unsafe { keep_both_3(1,) }) == (2)));
+    assert!(((unsafe { widen_4(1_u32,) }) == (1_u64)));
+    assert!(((unsafe { widen_5(1_u64,) }) == (4294967296_u64)));
     return 0;
 }
 pub unsafe fn __cpp2rust_init_globals() {}