Constant folding for integer casts (#8095)

1 files changed, 60 insertions, 0 deletions

diff --git a/tests/arithm/tcast.nim b/tests/arithm/tcast.nim
new file mode 100644
index 000000000..954e2e677
--- /dev/null
+++ b/tests/arithm/tcast.nim
@@ -0,0 +1,60 @@
+discard """
+  output: '''
+B0
+B1
+B2
+B3
+'''
+"""
+
+template crossCheck(ty: untyped, exp: untyped) =
+  let rt = ty(exp)
+  const ct = ty(exp)
+  if $rt != $ct:
+    echo "Got ", ct
+    echo "Expected ", rt
+
+block:
+  when true:
+    echo "B0"
+    crossCheck(int8, 0'i16 - 5'i16)
+    crossCheck(int16, 0'i32 - 5'i32)
+    crossCheck(int32, 0'i64 - 5'i64)
+
+    echo "B1"
+    crossCheck(uint8, 0'u8 - 5'u8)
+    crossCheck(uint16, 0'u16 - 5'u16)
+    crossCheck(uint32, 0'u32 - 5'u32)
+    crossCheck(uint64, 0'u64 - 5'u64)
+
+    echo "B2"
+    crossCheck(uint8, uint8.high + 5'u8)
+    crossCheck(uint16, uint16.high + 5'u16)
+    crossCheck(uint32, uint32.high + 5'u32)
+    crossCheck(uint64, (-1).uint64 + 5'u64)
+
+    echo "B3"
+    crossCheck(int8, 0'u8 - 5'u8)
+    crossCheck(int16, 0'u16 - 5'u16)
+    crossCheck(int32, 0'u32 - 5'u32)
+    crossCheck(int64, 0'u64 - 5'u64)
+
+  # crossCheck(int8, 0'u16 - 129'u16)
+  # crossCheck(uint8, 0'i16 + 257'i16)
+
+  # Signed integer {under,over}flow is guarded against
+
+  # crossCheck(int8, int8.high + 5'i8)
+  # crossCheck(int16, int16.high + 5'i16)
+  # crossCheck(int32, int32.high + 5'i32)
+  # crossCheck(int64, int64.high + 5'i64)
+
+  # crossCheck(int8, int8.low - 5'i8)
+  # crossCheck(int16, int16.low - 5'i16)
+  # crossCheck(int32, int32.low - 5'i32)
+  # crossCheck(int64, int64.low - 5'i64)
+
+  # crossCheck(uint8, 0'i8 - 5'i8)
+  # crossCheck(uint16, 0'i16 - 5'i16)
+  # crossCheck(uint32, 0'i32 - 5'i32)
+  # crossCheck(uint64, 0'i64 - 5'i64)