Add type asserts to (try)parse(::TimeType, ...) to help inference.

Cthulhoni · Apr 7, 2021 · 8a14ef2 · 8a14ef2
1 parent 8218480
commit 8a14ef2
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/stdlib/Dates/src/parse.jl b/stdlib/Dates/src/parse.jl
@@ -282,7 +282,7 @@ function Base.parse(::Type{T}, str::AbstractString, df::DateFormat=default_forma
     val = tryparsenext_internal(T, str, pos, len, df, true)
     @assert val !== nothing
     values, endpos = val
-    return T(values...)
+    return T(values...)::T
 end
 
 function Base.tryparse(::Type{T}, str::AbstractString, df::DateFormat=default_format(T)) where T<:TimeType
@@ -292,7 +292,7 @@ function Base.tryparse(::Type{T}, str::AbstractString, df::DateFormat=default_fo
     values, endpos = res
     if validargs(T, values...) === nothing
         # TODO: validargs gets called twice, since it's called again in the T constructor
-        return T(values...)
+        return T(values...)::T
     end
     return nothing
 end

diff --git a/stdlib/Dates/test/io.jl b/stdlib/Dates/test/io.jl
@@ -572,4 +572,14 @@ end
     end
 end
 
+@testset "inference with dynamic dateformat string" begin
+    datetime = DateTime(2020, 4, 7)
+    f1() = DateTime("2020-04-07", "yyyy-mm-dd")
+    f2() = DateTime("2020-04-07", DateFormat("yyyy-mm-dd"))
+    f3() = parse(DateTime, "2020-04-07", DateFormat("yyyy-mm-dd"))
+    @test (@inferred f1()) == (@inferred f2()) == (@inferred f3()) == datetime
+    g() = tryparse(DateTime, "2020-04-07", DateFormat("yyyy-mm-dd"))
+    @test (@inferred Nothing g()) == datetime
+end
+
 end