Fix #35231 improve type error message (#35238)

JuliaLang · Mar 24, 2020 · f449765 · f449765 · nanosoldier · Mar 25, 2020
1 parent e3e9def
commit f449765
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diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
@@ -2203,7 +2203,7 @@ julia> "Hello!" :: IntOrString
 "Hello!"
 
 julia> 1.0 :: IntOrString
-ERROR: TypeError: in typeassert, expected Union{Int64, AbstractString}, got Float64
+ERROR: TypeError: in typeassert, expected Union{Int64, AbstractString}, got a value of type Float64
 ```
 """
 Union
@@ -2237,7 +2237,7 @@ Outside of declarations `::` is used to assert that expressions and variables in
 # Examples
 ```jldoctest
 julia> (1+2)::AbstractFloat
-ERROR: TypeError: typeassert: expected AbstractFloat, got Int64
+ERROR: TypeError: typeassert: expected AbstractFloat, got a value of type Int64
 
 julia> (1+2)::Int
 3
@@ -2320,7 +2320,7 @@ The syntax `x::type` calls this function.
 # Examples
 ```jldoctest
 julia> typeassert(2.5, Int)
-ERROR: TypeError: in typeassert, expected Int64, got Float64
+ERROR: TypeError: in typeassert, expected Int64, got a value of type Float64
 Stacktrace:
 [...]
 ```

diff --git a/base/errorshow.jl b/base/errorshow.jl
@@ -139,7 +139,7 @@ function showerror(io::IO, ex::TypeError)
         elseif isa(ex.got, Type)
             targs = ("Type{", ex.got, "}")
         else
-            targs = (typeof(ex.got),)
+            targs = ("a value of type $(typeof(ex.got))",)
         end
         if ex.context == ""
             ctx = "in $(ex.func)"

diff --git a/doc/src/manual/types.md b/doc/src/manual/types.md
@@ -70,7 +70,7 @@ an exception is thrown, otherwise, the left-hand value is returned:
 
 ```jldoctest
 julia> (1+2)::AbstractFloat
-ERROR: TypeError: in typeassert, expected AbstractFloat, got Int64
+ERROR: TypeError: in typeassert, expected AbstractFloat, got a value of type Int64
 
 julia> (1+2)::Int
 3
@@ -493,7 +493,7 @@ julia> "Hello!" :: IntOrString
 "Hello!"
 
 julia> 1.0 :: IntOrString
-ERROR: TypeError: in typeassert, expected Union{Int64, AbstractString}, got Float64
+ERROR: TypeError: in typeassert, expected Union{Int64, AbstractString}, got a value of type Float64
 ```
 
 The compilers for many languages have an internal union construct for reasoning about types; Julia
@@ -812,7 +812,7 @@ julia> Pointy{AbstractString}
 ERROR: TypeError: in Pointy, in T, expected T<:Real, got Type{AbstractString}
 
 julia> Pointy{1}
-ERROR: TypeError: in Pointy, in T, expected T<:Real, got Int64
+ERROR: TypeError: in Pointy, in T, expected T<:Real, got a value of type Int64
 ```
 
 Type parameters for parametric composite types can be restricted in the same manner:

diff --git a/test/errorshow.jl b/test/errorshow.jl
@@ -301,15 +301,15 @@ let undefvar
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"
     err_str = @except_str 0::AbstractFloat TypeError
-    @test err_str == "TypeError: in typeassert, expected AbstractFloat, got $Int"
+    @test err_str == "TypeError: in typeassert, expected AbstractFloat, got a value of type $Int"
     err_str = @except_str 0::7 TypeError
-    @test err_str == "TypeError: in typeassert, expected Type, got $Int"
+    @test err_str == "TypeError: in typeassert, expected Type, got a value of type $Int"
     err_str = @except_str "" <: AbstractString TypeError
-    @test err_str == "TypeError: in <:, expected Type, got String"
+    @test err_str == "TypeError: in <:, expected Type, got a value of type String"
     err_str = @except_str AbstractString <: "" TypeError
-    @test err_str == "TypeError: in <:, expected Type, got String"
+    @test err_str == "TypeError: in <:, expected Type, got a value of type String"
     err_str = @except_str Type{""} TypeError
-    @test err_str == "TypeError: in Type, in parameter, expected Type, got String"
+    @test err_str == "TypeError: in Type, in parameter, expected Type, got a value of type String"
     err_str = @except_str TypeWithIntParam{Any} TypeError
     @test err_str == "TypeError: in TypeWithIntParam, in T, expected T<:Integer, got Type{Any}"
     err_str = @except_str Type{Vararg} TypeError