fix #27554, deprecate try without catch or finally

NEWS.md

@@ -220,6 +220,9 @@ Language changes
     is deprecated. It will likely be reclaimed in a later version for passing keyword
     arguments. Note this does not affect updating operators like `+=` ([#25631]).
 
+  * `try` blocks without `catch` or `finally` are no longer allowed. An explicit empty
+    `catch` block should be written instead ([#27554]).
+
 Breaking changes
 ----------------
 

base/compiler/tfuncs.jl

@@ -994,6 +994,7 @@ function builtin_tfunction(@nospecialize(f), argtypes::Array{Any,1},
             argvals = anymap(a -> a.val, argtypes)
             try
                 return Const(f(argvals...))
+            catch
             end
         end
         iidx = Int(reinterpret(Int32, f::IntrinsicFunction)) + 1

base/docs/basedocs.jl

@@ -469,8 +469,7 @@ end
 
 `try`/`catch` statements also allow the `Exception` to be saved in a variable, e.g. `catch y`.
 
-The `catch` clause is not strictly necessary; when omitted, the default return value is
-[`nothing`](@ref). The power of the `try`/`catch` construct lies in the ability to unwind a deeply
+The power of the `try`/`catch` construct lies in the ability to unwind a deeply
 nested computation immediately to a much higher level in the stack of calling functions.
 """
 kw"try", kw"catch"

base/download.jl

@@ -33,6 +33,7 @@ else
                     Sys.which(checkcmd)
                     downloadcmd = checkcmd
                     break
+                catch
                 end
             end
         end

base/iostream.jl

@@ -485,6 +485,7 @@ function read(s::IOStream)
         if pos > 0
             sz -= pos
         end
+    catch
     end
     b = StringVector(sz<=0 ? 1024 : sz)
     nr = readbytes_all!(s, b, typemax(Int))

doc/src/manual/control-flow.md

@@ -790,12 +790,6 @@ catch
 end
 ```
 
-The `catch` clause is not strictly necessary; when omitted, the default return value is `nothing`.
-
-```jldoctest
-julia> try error() end # Returns nothing
-```
-
 The power of the `try/catch` construct lies in the ability to unwind a deeply nested computation
 immediately to a much higher level in the stack of calling functions. There are situations where
 no error has occurred, but the ability to unwind the stack and pass a value to a higher level

src/julia-parser.scm

@@ -1505,7 +1505,8 @@
              ((eq? nxt 'end)
               (list* 'try try-block (or catchv 'false)
                      ;; default to empty catch block in `try ... end`
-                     (or catchb (if finalb 'false '(block)))
+                     (or catchb (if finalb 'false (begin (parser-depwarn s "try without catch or finally" "")
+                                                         '(block))))
                      (if finalb (list finalb) '())))
              ((and (eq? nxt 'catch)
                    (not catchb))

stdlib/Distributed/src/clusterserialize.jl

@@ -212,6 +212,7 @@ function original_ex(s::ClusterSerializer, ex_str, remote_stktrace)
     local pid_str = ""
     try
         pid_str = string(" from worker ", worker_id_from_socket(s.io))
+    catch
     end
 
     stk_str = remote_stktrace ? "Remote" : "Local"

stdlib/Distributed/test/distributed_exec.jl

@@ -954,6 +954,7 @@ const get_num_threads = function() # anonymous so it will be serialized when cal
         if Sys.isapple()
             return tryparse(Cint, get(ENV, "VECLIB_MAXIMUM_THREADS", "1"))
         end
+    catch
     end
 
     return nothing

stdlib/InteractiveUtils/src/InteractiveUtils.jl

@@ -68,10 +68,10 @@ function versioninfo(io::IO=stdout; verbose::Bool=false, packages::Bool=false)
     if verbose
         lsb = ""
         if Sys.islinux()
-            try lsb = readchomp(pipeline(`lsb_release -ds`, stderr=devnull)) end
+            try lsb = readchomp(pipeline(`lsb_release -ds`, stderr=devnull)); catch; end
         end
         if Sys.iswindows()
-            try lsb = strip(read(`$(ENV["COMSPEC"]) /c ver`, String)) end
+            try lsb = strip(read(`$(ENV["COMSPEC"]) /c ver`, String)); catch; end
         end
         if !isempty(lsb)
             println(io, "      ", lsb)
@@ -95,7 +95,7 @@ function versioninfo(io::IO=stdout; verbose::Bool=false, packages::Bool=false)
 
     if verbose
         println(io, "  Memory: $(Sys.total_memory()/2^30) GB ($(Sys.free_memory()/2^20) MB free)")
-        try println(io, "  Uptime: $(Sys.uptime()) sec") end
+        try println(io, "  Uptime: $(Sys.uptime()) sec"); catch; end
         print(io, "  Load Avg: ")
         Base.print_matrix(io, Sys.loadavg()')
         println(io)

stdlib/LibGit2/src/LibGit2.jl

@@ -504,6 +504,7 @@ function checkout!(repo::GitRepo, commit::AbstractString = "";
                 head_name = string(GitHash(head_ref))
             end
         end
+    catch
     end
 
     # search for commit to get a commit object

stdlib/LibGit2/src/commit.jl

@@ -114,6 +114,7 @@ function commit(repo::GitRepo, msg::AbstractString;
     if isempty(parent_ids)
         try # if throws then HEAD not found -> empty repo
             Base.push!(parent_ids, GitHash(repo, refname))
+        catch
         end
     end
 

stdlib/LibGit2/src/config.jl

@@ -130,7 +130,7 @@ end
 
 function get(c::GitConfig, name::AbstractString, default::T) where T
     res = default
-    try res = get(T,c,name) end
+    try res = get(T,c,name); catch; end
     return res
 end
 

stdlib/LibGit2/test/libgit2.jl

@@ -2694,6 +2694,7 @@ mktempdir() do dir
                 # In some environments, namely Macs, the hostname "macbook.local" is bound
                 # to the external address while "macbook" is bound to the loopback address.
                 pushfirst!(hostnames, replace(gethostname(), r"\..*$" => ""))
+            catch
             end
 
             loopback = ip"127.0.0.1"

stdlib/LinearAlgebra/src/dense.jl

@@ -1201,6 +1201,7 @@ function factorize(A::StridedMatrix{T}) where T
                 if (herm & (T <: Complex)) | sym
                     try
                         return ldlt!(SymTridiagonal(diag(A), diag(A, -1)))
+                    catch
                     end
                 end
                 return lu(Tridiagonal(diag(A, -1), diag(A), diag(A, 1)))

stdlib/OldPkg/src/entry.jl

@@ -63,6 +63,7 @@ function add(pkg::AbstractString, vers::VersionSet)
                     try
                         LibGit2.fetch(repo)
                         outdated = LibGit2.isdiff(repo, "origin/$branch") ? (:yes) : (:no)
+                    catch
                     end
                 end
             else

stdlib/REPL/src/LineEdit.jl

@@ -2020,6 +2020,7 @@ AnyDict(
     "^C" => (s,o...)->begin
         try # raise the debugger if present
             ccall(:jl_raise_debugger, Int, ())
+        catch
         end
         cancel_beep(s)
         move_input_end(s)

stdlib/REPL/src/REPL.jl

@@ -217,6 +217,7 @@ function run_frontend(repl::BasicREPL, backend::REPLBackendRef)
                 if isa(e,InterruptException)
                     try # raise the debugger if present
                         ccall(:jl_raise_debugger, Int, ())
+                    catch
                     end
                     line = ""
                     interrupted = true

stdlib/Random/src/RNGs.jl

@@ -247,6 +247,7 @@ function make_seed()
             seed = hash(seed, parse(UInt64,
                                     read(pipeline(`ifconfig`, `sha1sum`), String)[1:40],
                                     base = 16))
+        catch
         end
         return make_seed(seed)
     end

stdlib/SHA/test/runtests.jl

@@ -278,6 +278,7 @@ for f in sha_funcs
         f(UInt32[0x23467, 0x324775])
         warn("Non-UInt8 Arrays should fail")
         nerrors += 1
+    catch
     end
 end
 

stdlib/SparseArrays/test/sparse.jl

@@ -1065,11 +1065,11 @@ end
 
     A = Matrix{Int}(I, 0, 0)
     S = sparse(A)
-    iA = try argmax(A) end
-    iS = try argmax(S) end
+    iA = try argmax(A); catch; end
+    iS = try argmax(S); catch; end
     @test iA === iS === nothing
-    iA = try argmin(A) end
-    iS = try argmin(S) end
+    iA = try argmin(A); catch; end
+    iS = try argmin(S); catch; end
     @test iA === iS === nothing
 end
 

test/char.jl

@@ -205,7 +205,7 @@ end
             @test eof(io)
             close(io)
         end
-   finally
+    finally
         rm(file, force=true)
     end
 end

test/compiler/compiler.jl

@@ -1515,6 +1515,7 @@ function h25579(g)
     try
         h = -1.25
         error("continue at catch block")
+    catch
     end
     return t ? typeof(h) : typeof(h)
 end

test/core.jl

@@ -770,6 +770,7 @@ begin
             global try_finally_glo_after = 1
         end
         global gothere = 1
+    catch
     end
     @test try_finally_loc_after == 0
     @test try_finally_glo_after == 1
@@ -799,7 +800,7 @@ begin
     @test retfinally() == 5
     @test glo == 18
 
-    @test try error() end === nothing
+    @test try error(); catch; end === nothing
 end
 
 # issue #12806
@@ -1270,6 +1271,7 @@ let
     function f()
         try
             return 1
+        catch
         end
     end
     @test f() == 1
@@ -1658,6 +1660,7 @@ try
     (function() end)(1)
     # should throw an argument count error
     @test false
+catch
 end
 
 # issue #4526
@@ -1881,6 +1884,7 @@ try
     # try running this code in a different context that triggers the codegen
     # assertion `assert(isboxed || v.typ == typ)`.
     f5142()
+catch
 end
 
 primitive type Int5142b 8 end
@@ -2282,6 +2286,7 @@ let
     # This can throw an error, but shouldn't segfault
     try
         issue7897!(sa, zeros(10))
+    catch
     end
 end
 
@@ -2605,6 +2610,7 @@ try
     mutable struct Foo{T}
         val::Bar{T}
     end
+catch
 end
 GC.gc()
 redirect_stdout(OLD_STDOUT)

test/error.jl

@@ -55,7 +55,7 @@ end
     @test c[1] == 1
 
     c = [0]
-    ex = try retry(foo_error, check=(s,e)->(s,try e.http_status_code == "503" end != true))(c,2) catch e; e end
+    ex = try retry(foo_error, check=(s,e)->(s,try e.http_status_code == "503"; catch; end != true))(c,2) catch e; e end
     @test typeof(ex) == ErrorException
     @test ex.msg == "foo"
     @test c[1] == 2

test/read.jl

@@ -127,7 +127,7 @@ end
 open_streams = []
 function cleanup()
     for s_ in open_streams
-        try close(s_) end
+        try close(s_); catch; end
     end
     empty!(open_streams)
     for tsk in tasks

test/runtests.jl

@@ -192,7 +192,7 @@ cd(dirname(@__FILE__)) do
         isa(e, InterruptException) || rethrow(e)
         # If the test suite was merely interrupted, still print the
         # summary, which can be useful to diagnose what's going on
-        foreach(task->try; schedule(task, InterruptException(); error=true); end, all_tasks)
+        foreach(task->try; schedule(task, InterruptException(); error=true); catch; end, all_tasks)
         foreach(wait, all_tasks)
     finally
         if isa(stdin, Base.TTY)

test/spawn.jl

@@ -165,6 +165,7 @@ let r, t
     t = @async begin
         try
             wait(r)
+        catch
         end
         p = run(`$sleepcmd 1`, wait=false); wait(p)
         @test p.exitcode == 0

test/threads.jl

@@ -465,6 +465,7 @@ function test_load_and_lookup_18020(n)
             ccall(:jl_load_and_lookup,
                   Ptr{Cvoid}, (Cstring, Cstring, Ref{Ptr{Cvoid}}),
                   "$i", :f, C_NULL)
+        catch
         end
     end
 end