fix(parser): warn on short final rows (#1193)

Only suppress the short-row warning at EOF when the parser consumed an explicit trailing delimiter. Preserve the valid empty-field behavior from #948 and add regression coverage with and without a final newline.

Fixes #1190

Author: quinnj

src/file.jl

@@ -678,13 +678,12 @@ Base.@propagate_inbounds function parserow(startpos, row, numwarnings, ctx::Cont
         else
             if i < ncols
                 if Parsers.newline(code) || pos > len
-                    # in https://github.com/JuliaData/CSV.jl/issues/948,
-                    # it was noticed that if we reached the EOF right before parsing
-                    # the last expected column, then the warning is a bit spurious.
-                    # The final value is `missing` and the csv writer chose to just
-                    # "close" the file w/o including a final newline
-                    # we can treat this special-case as "valid" and not emit a warning
-                    if !(pos > len && i == (ncols - 1))
+                    # In https://github.com/JuliaData/CSV.jl/issues/948,
+                    # the delimiter for an empty final field was the final byte of
+                    # the input. Treat that explicit empty field as valid even
+                    # without a trailing newline, but still warn if the row ended
+                    # before the final field's delimiter was present.
+                    if !(pos > len && i == (ncols - 1) && Parsers.delimited(code))
                         ctx.silencewarnings || numwarnings[] > ctx.maxwarnings || notenoughcolumns(i, ncols, rowoffset + row)
                         !ctx.silencewarnings && numwarnings[] == ctx.maxwarnings && toomanywwarnings()
                         numwarnings[] += 1

test/basics.jl

@@ -804,10 +804,16 @@ f = CSV.File(IOBuffer(data); header=false, types=Dict(1 => String), typemap=Dict
 @test f.types == [i == 1 ? String : Int8 for i = 1:60_000]
 
 # 948
-f = CSV.File(IOBuffer("a,b\n1,2\n3,"))
+f = @test_logs CSV.File(IOBuffer("a,b\n1,2\n3,"))
 @test f.a == [1, 3]
 @test isequal(f.b, [2, missing])
 
+# 1190
+for source in ("a,b,c\n1,2,3\n4,5", "a,b,c\n1,2,3\n4,5\n")
+    f = @test_logs (:warn, r"only found 2 / 3 columns around data row: 2") CSV.File(IOBuffer(source))
+    @test isequal(f.c, [3, missing])
+end
+
 # duplicate column names
 f = CSV.File(IOBuffer("a,a,a\n"))
 @test f.names == [:a, :a_1, :a_2]