compiler: combine `@intCast` safety checks

`castTruncatedData` was a poorly worded error (all shrinking casts
"truncate bits", it's just that we assume those bits to be zext/sext of
the other bits!), and `negativeToUnsigned` was a pointless distinction
which forced the compiler to emit worse code (since two separate safety
checks were required for casting e.g. 'i32' to 'u16') and wasn't even
implemented correctly. This commit combines those safety panics into one
function, `integerOutOfBounds`. The name maybe isn't perfect, but that's
not hugely important; what matters is the new default message, which is
clearer than the old ones: "integer does not fit in destination type".

1 files changed, 6 insertions, 10 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index 3c4fc555cb..f051a62af3 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -10263,7 +10263,7 @@ fn zirIntCast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
     const dest_ty = try sema.resolveDestType(block, src, extra.lhs, .remove_eu_opt, "@intCast");
     const operand = try sema.resolveInst(extra.rhs);
 
-    return sema.intCast(block, block.nodeOffset(inst_data.src_node), dest_ty, src, operand, operand_src, true, false);
+    return sema.intCast(block, block.nodeOffset(inst_data.src_node), dest_ty, src, operand, operand_src);
 }
 
 fn intCast(
@@ -10274,8 +10274,6 @@ fn intCast(
     dest_ty_src: LazySrcLoc,
     operand: Air.Inst.Ref,
     operand_src: LazySrcLoc,
-    runtime_safety: bool,
-    safety_panics_are_enum: bool,
 ) CompileError!Air.Inst.Ref {
     const pt = sema.pt;
     const zcu = pt.zcu;
@@ -10294,7 +10292,7 @@ fn intCast(
 
     if ((try sema.typeHasOnePossibleValue(dest_ty))) |opv| {
         // requirement: intCast(u0, input) iff input == 0
-        if (runtime_safety and block.wantSafety()) {
+        if (block.wantSafety()) {
             try sema.requireRuntimeBlock(block, src, operand_src);
             const wanted_info = dest_scalar_ty.intInfo(zcu);
             const wanted_bits = wanted_info.bits;
@@ -10311,7 +10309,7 @@ fn intCast(
                     const is_in_range = try block.addBinOp(.cmp_lte, operand, zero_inst);
                     break :ok is_in_range;
                 };
-                try sema.addSafetyCheck(block, src, ok, if (safety_panics_are_enum) .invalid_enum_value else .cast_truncated_data);
+                try sema.addSafetyCheck(block, src, ok, .integer_out_of_bounds);
             }
         }
 
@@ -10319,10 +10317,9 @@ fn intCast(
     }
 
     try sema.requireRuntimeBlock(block, src, operand_src);
-    if (runtime_safety and block.wantSafety()) {
+    if (block.wantSafety()) {
         if (zcu.backendSupportsFeature(.panic_fn)) {
-            _ = try sema.preparePanicId(src, .negative_to_unsigned);
-            _ = try sema.preparePanicId(src, .cast_truncated_data);
+            _ = try sema.preparePanicId(src, .integer_out_of_bounds);
         }
         return block.addTyOp(.intcast_safe, dest_ty, operand);
     }
@@ -37984,8 +37981,7 @@ fn getExpectedBuiltinFnType(sema: *Sema, decl: Zcu.BuiltinDecl) CompileError!Typ
         .@"panic.castToNull",
         .@"panic.incorrectAlignment",
         .@"panic.invalidErrorCode",
-        .@"panic.castTruncatedData",
-        .@"panic.negativeToUnsigned",
+        .@"panic.integerOutOfBounds",
         .@"panic.integerOverflow",
         .@"panic.shlOverflow",
         .@"panic.shrOverflow",