fix handling of unknown setting in @constprop, fix error message (#56946)

Co-authored-by: Shuhei Kadowaki <[email protected]>

Author: nsajko

base/expr.jl

@@ -401,13 +401,14 @@ macro constprop(setting)
 end
 
 function constprop_setting(@nospecialize setting)
+    s = setting
     isa(setting, QuoteNode) && (setting = setting.value)
     if setting === :aggressive
         return :aggressive_constprop
     elseif setting === :none
         return :no_constprop
     end
-    throw(ArgumentError(LazyString("@constprop "), setting, "not supported"))
+    throw(ArgumentError(LazyString("`Base.@constprop ", s, "` not supported")))
 end
 
 """

test/misc.jl

@@ -1612,3 +1612,15 @@ let errs = IOBuffer()
         '`, devnull, stdout, errs)
     @test occursin("disable_new_worlds", String(take!(errs)))
 end
+
+@testset "`@constprop`, `@assume_effects` handling of an unknown setting" begin
+    for x ∈ ("constprop", "assume_effects")
+        try
+            eval(Meta.parse("Base.@$x :unknown f() = 3"))
+            error("unexpectedly reached")
+        catch e
+            e::LoadError
+            @test e.error isa ArgumentError
+        end
+    end
+end