Sema: rewrite semantic analysis of function calls

This rewrite improves some error messages, hugely simplifies the logic,
and fixes several bugs. One of these bugs is technically a new rule
which Andrew and I agreed on: if a parameter has a comptime-only type
but is not declared `comptime`, then the corresponding call argument
should not be *evaluated* at comptime; only resolved. Implementing this
required changing how function types work a little, which in turn
required allowing a new kind of function coercion for some generic use
cases: function coercions are now allowed to implicitly *remove*
`comptime` annotations from parameters with comptime-only types. This is
okay because removing the annotation affects only the call site.

Resolves: #22262

5 files changed, 15 insertions, 7 deletions

diff --git a/lib/std/math/log_int.zig b/lib/std/math/log_int.zig
index 376aa69a4d..96227639d0 100644
--- a/lib/std/math/log_int.zig
+++ b/lib/std/math/log_int.zig
@@ -61,6 +61,7 @@ pub fn log_int(comptime T: type, base: T, x: T) Log2Int(T) {
 }
 
 test "log_int" {
+    @setEvalBranchQuota(2000);
     // Test all unsigned integers with 2, 3, ..., 64 bits.
     // We cannot test 0 or 1 bits since base must be > 1.
     inline for (2..64 + 1) |bits| {
diff --git a/lib/std/os/windows.zig b/lib/std/os/windows.zig
index c56e27d8ec..ceed0618d1 100644
--- a/lib/std/os/windows.zig
+++ b/lib/std/os/windows.zig
@@ -1468,6 +1468,7 @@ fn mountmgrIsVolumeName(name: []const u16) bool {
 }
 
 test mountmgrIsVolumeName {
+    @setEvalBranchQuota(2000);
     const L = std.unicode.utf8ToUtf16LeStringLiteral;
     try std.testing.expect(mountmgrIsVolumeName(L("\\\\?\\Volume{383da0b0-717f-41b6-8c36-00500992b58d}")));
     try std.testing.expect(mountmgrIsVolumeName(L("\\??\\Volume{383da0b0-717f-41b6-8c36-00500992b58d}")));
diff --git a/lib/std/zig.zig b/lib/std/zig.zig
index 7af8bacb34..6fec585326 100644
--- a/lib/std/zig.zig
+++ b/lib/std/zig.zig
@@ -749,6 +749,8 @@ pub const SimpleComptimeReason = enum(u32) {
     array_mul_factor,
     slice_cat_operand,
     comptime_call_target,
+    inline_call_target,
+    generic_call_target,
     wasm_memory_index,
     work_group_dim_index,
 
@@ -791,7 +793,6 @@ pub const SimpleComptimeReason = enum(u32) {
     struct_field_default_value,
     enum_field_tag_value,
     slice_single_item_ptr_bounds,
-    comptime_param_arg,
     stored_to_comptime_field,
     stored_to_comptime_var,
     casted_to_comptime_enum,
@@ -828,6 +829,8 @@ pub const SimpleComptimeReason = enum(u32) {
             .array_mul_factor     => "array multiplication factor must be comptime-known",
             .slice_cat_operand    => "slice being concatenated must be comptime-known",
             .comptime_call_target => "function being called at comptime must be comptime-known",
+            .inline_call_target   => "function being called inline must be comptime-known",
+            .generic_call_target  => "generic function being called must be comptime-known",
             .wasm_memory_index    => "wasm memory index must be comptime-known",
             .work_group_dim_index => "work group dimension index must be comptime-known",
 
@@ -865,7 +868,6 @@ pub const SimpleComptimeReason = enum(u32) {
             .struct_field_default_value   => "struct field default value must be comptime-known",
             .enum_field_tag_value         => "enum field tag value must be comptime-known",
             .slice_single_item_ptr_bounds => "slice of single-item pointer must have comptime-known bounds",
-            .comptime_param_arg           => "argument to comptime parameter must be comptime-known",
             .stored_to_comptime_field     => "value stored to a comptime field must be comptime-known",
             .stored_to_comptime_var       => "value stored to a comptime variable must be comptime-known",
             .casted_to_comptime_enum      => "value casted to enum with 'comptime_int' tag type must be comptime-known",
diff --git a/lib/std/zig/AstGen.zig b/lib/std/zig/AstGen.zig
index d318a9f3e5..1355c7cc77 100644
--- a/lib/std/zig/AstGen.zig
+++ b/lib/std/zig/AstGen.zig
@@ -10209,9 +10209,6 @@ fn callExpr(
 
     const callee = try calleeExpr(gz, scope, ri.rl, call.ast.fn_expr);
     const modifier: std.builtin.CallModifier = blk: {
-        if (gz.is_comptime) {
-            break :blk .compile_time;
-        }
         if (call.async_token != null) {
             break :blk .async_kw;
         }
diff --git a/lib/std/zig/Zir.zig b/lib/std/zig/Zir.zig
index 21f59f8e83..3b27f1cf5b 100644
--- a/lib/std/zig/Zir.zig
+++ b/lib/std/zig/Zir.zig
@@ -4735,6 +4735,7 @@ pub const FnInfo = struct {
     body: []const Inst.Index,
     ret_ty_ref: Zir.Inst.Ref,
     total_params_len: u32,
+    inferred_error_set: bool,
 };
 
 pub fn getParamBody(zir: Zir, fn_inst: Inst.Index) []const Zir.Inst.Index {
@@ -4774,8 +4775,9 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
         body: []const Inst.Index,
         ret_ty_ref: Inst.Ref,
         ret_ty_body: []const Inst.Index,
+        ies: bool,
     } = switch (tags[@intFromEnum(fn_inst)]) {
-        .func, .func_inferred => blk: {
+        .func, .func_inferred => |tag| blk: {
             const inst_data = datas[@intFromEnum(fn_inst)].pl_node;
             const extra = zir.extraData(Inst.Func, inst_data.payload_index);
 
@@ -4805,6 +4807,7 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
                 .ret_ty_ref = ret_ty_ref,
                 .ret_ty_body = ret_ty_body,
                 .body = body,
+                .ies = tag == .func_inferred,
             };
         },
         .func_fancy => blk: {
@@ -4812,7 +4815,7 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
             const extra = zir.extraData(Inst.FuncFancy, inst_data.payload_index);
 
             var extra_index: usize = extra.end;
-            var ret_ty_ref: Inst.Ref = .void_type;
+            var ret_ty_ref: Inst.Ref = .none;
             var ret_ty_body: []const Inst.Index = &.{};
 
             if (extra.data.bits.has_cc_body) {
@@ -4828,6 +4831,8 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
             } else if (extra.data.bits.has_ret_ty_ref) {
                 ret_ty_ref = @enumFromInt(zir.extra[extra_index]);
                 extra_index += 1;
+            } else {
+                ret_ty_ref = .void_type;
             }
 
             extra_index += @intFromBool(extra.data.bits.has_any_noalias);
@@ -4839,6 +4844,7 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
                 .ret_ty_ref = ret_ty_ref,
                 .ret_ty_body = ret_ty_body,
                 .body = body,
+                .ies = extra.data.bits.is_inferred_error,
             };
         },
         else => unreachable,
@@ -4860,6 +4866,7 @@ pub fn getFnInfo(zir: Zir, fn_inst: Inst.Index) FnInfo {
         .ret_ty_ref = info.ret_ty_ref,
         .body = info.body,
         .total_params_len = total_params_len,
+        .inferred_error_set = info.ies,
     };
 }