Add Base.alignment methods

src/display.jl

@@ -252,3 +252,13 @@ superscript(i::Integer) = map(repr(i)) do c
     c == '0' ? '\u2070' :
     error("unexpected character")
 end
+
+function Base.alignment(io::IO, x::Quantity)
+    if isunitless(unit(x))
+        return Base.alignment(io, x.val)
+    end
+    length = Base.alignment_from_show(io, x)
+    left, _ = Base.alignment(io, x.val)
+    left += BracketStyle(x.val) != NoBrackets()
+    return left, length - left
+end

src/logarithm.jl

@@ -315,6 +315,17 @@ function Base.show(io::IO, x::Level)
     nothing
 end
 
+function Base.alignment(io::IO, x::Gain)
+    length = Base.alignment_from_show(io, x)
+    left, _ = Base.alignment(io, x.val)
+    return left, length - left
+end
+function Base.alignment(io::IO, x::Level)
+    length = Base.alignment_from_show(io, x)
+    left, _ = Base.alignment(io, ustrip(x))
+    return left, length - left
+end
+
 BracketStyle(::Type{<:Union{Level,Gain}}) = SquareBrackets()
 
 """

test/runtests.jl

@@ -1710,6 +1710,12 @@ Base.show(io::IO, ::MIME"text/plain", ::Foo) = print(io, "42.0")
         @test repr(1.0 * u"m * s * kg^(-1//2)") ==
             (Sys.isapple() ? "1.0 m s kg⁻¹ᐟ²" : "1.0 m s kg^-1/2")
     end
+    @test Base.alignment(stdout, (1//3)m)  == Base.alignment(stdout, 1//3) .+ (0, 2)
+    @test Base.alignment(stdout, (2+3im)m) == Base.alignment(stdout, 2+3im) .+ (1, 3)
+    @test Base.alignment(stdout, 3.0dB)    == Base.alignment(stdout, 3.0) .+ (0, 3)
+    @test Base.alignment(stdout, 3.0dBm)   == Base.alignment(stdout, 3.0) .+ (0, 4)
+    @test Base.alignment(stdout, 3.0dB*s)  == Base.alignment(stdout, 3.0) .+ (1, 6)
+    @test Base.alignment(stdout, 3.0dBm*s) == Base.alignment(stdout, 3.0) .+ (1, 7)
 end
 
 @testset "DimensionError message" begin