Sema: rewrite analyzeMinMax

I only wanted to fix a bug originally, but this logic was kind of a
rat's nest. But now... okay, it still *is*, but it's now a slightly more
navigable nest, with cute little signs occasionally, painted by adorable
rats desparately trying to follow the specification.

Hopefully #3806 comes along at some point to simplify this logic a
little.

Resolves: #23139

test/behavior/maximum_minimum.zig

@@ -351,3 +351,44 @@ test "@min resulting in u0" {
     const x = S.min(0, 1);
     try expect(x == 0);
 }
+
+test "@min/@max with runtime signed and unsigned integers of same size" {
+    const S = struct {
+        fn min(a: i32, b: u32) i32 {
+            return @min(a, b);
+        }
+        fn max(a: i32, b: u32) u32 {
+            return @max(a, b);
+        }
+    };
+
+    const min = S.min(std.math.minInt(i32), std.math.maxInt(u32));
+    try expect(min == std.math.minInt(i32));
+
+    const max = S.max(std.math.minInt(i32), std.math.maxInt(u32));
+    try expect(max == std.math.maxInt(u32));
+}
+
+test "@min/@max with runtime vectors of signed and unsigned integers of same size" {
+    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_x86_64 and builtin.target.ofmt != .elf and builtin.target.ofmt != .macho) return error.SkipZigTest;
+
+    const S = struct {
+        fn min(a: @Vector(2, i32), b: @Vector(2, u32)) @Vector(2, i32) {
+            return @min(a, b);
+        }
+        fn max(a: @Vector(2, i32), b: @Vector(2, u32)) @Vector(2, u32) {
+            return @max(a, b);
+        }
+    };
+
+    const a: @Vector(2, i32) = .{ std.math.minInt(i32), std.math.maxInt(i32) };
+    const b: @Vector(2, u32) = .{ std.math.maxInt(u32), std.math.minInt(u32) };
+
+    try expectEqual(@Vector(2, i32){ std.math.minInt(i32), std.math.minInt(u32) }, S.min(a, b));
+    try expectEqual(@Vector(2, u32){ std.math.maxInt(u32), std.math.maxInt(i32) }, S.max(a, b));
+}