syntax: Disallow using @goto to skip finally blocks (#60979)

Author: IanButterworth

JuliaLowering/src/binding_analysis.jl

@@ -183,7 +183,7 @@ function du_visit!(ctx, state::DefUseState, e)
         du_kill!(state)
         return false
 
-    elseif k in KSet"break symbolicgoto"
+    elseif k in KSet"break symbolicgoto oldsymbolicgoto"
         # this kill!() is not required for soundness since these are branch points
         # not merge points, but it's here for parity with flisp
         du_kill!(state)

JuliaLowering/src/compat.jl

@@ -539,6 +539,7 @@ function est_to_dst(st::SyntaxTree)
             [K"inert"(st[1]) ex]
         ]
         [K"symbolicgoto" lab] -> setattr!(mkleaf(st), :name_val, lab.name_val)
+        [K"oldsymbolicgoto" lab] -> setattr!(mkleaf(st), :name_val, lab.name_val)
         [K"symboliclabel" lab] -> setattr!(mkleaf(st), :name_val, lab.name_val)
         [K"symbolicblock" id body] -> if all(==('_'), id.name_val)
             @ast g st [K"symbolicblock" id=>K"Placeholder" rec(body)]

JuliaLowering/src/desugaring.jl

@@ -2118,6 +2118,7 @@ function expand_try(ctx, ex)
 
     if !isnothing(finally_)
         # TODO: check unmatched symbolic gotos in try.
+        # TODO: Disallow @goto from try/catch/else blocks when there's a finally clause
     end
 
     try_body = @ast ctx try_ [K"scope_block"(scope_type=:neutral) try_]

JuliaLowering/src/kinds.jl

@@ -41,6 +41,8 @@ function _register_kinds()
             "symboliclabel"
             # Goto named label
             "symbolicgoto"
+            # Goto named label (old syntax version, no try/finally check)
+            "oldsymbolicgoto"
             # Labeled block for `@label name expr` (block break)
             "symbolicblock"
             # Internal initializer for struct types, for inner constructors/functions

JuliaLowering/src/linear_ir.jl

@@ -774,7 +774,7 @@ function compile(ctx::LinearIRContext, ex, needs_value, in_tail_pos)
         elseif needs_value
             throw(LoweringError(ex, "misplaced label in value position"))
         end
-    elseif k == K"symbolicgoto"
+    elseif k == K"symbolicgoto" || k == K"oldsymbolicgoto"
         push!(ctx.symbolic_jump_origins, JumpOrigin(ex, length(ctx.code)+1, ctx))
         emit(ctx, newleaf(ctx, ex, K"TOMBSTONE")) # ? pop_exception
         emit(ctx, newleaf(ctx, ex, K"TOMBSTONE")) # ? leave

JuliaLowering/src/utils.jl

@@ -18,6 +18,7 @@ function _value_string(ex)
           k == K"static_parameter" ? "static_parameter" :
           k == K"symboliclabel" ? "label:$(ex.name_val)" :
           k == K"symbolicgoto" ? "goto:$(ex.name_val)" :
+          k == K"oldsymbolicgoto" ? "goto:$(ex.name_val)" :
           k == K"SourceLocation" ?
               "SourceLocation:$(JuliaSyntax.filename(ex)):$(join(source_location(ex), ':'))" :
           k == K"Value" && ex.value isa SourceRef ?

JuliaLowering/src/validation.jl

@@ -259,6 +259,7 @@ vst1(vcx::Validation1Context, st::SyntaxTree)::ValidationResult = @stm st begin
         all(vst1, vcx, [argt, lb, ub, bool]) & vst1_lam(vcx, lam)
     [K"symboliclabel" lab] -> vst1_ident(vcx, lab; lhs=true)
     [K"symbolicgoto" lab] -> vst1_ident(vcx, lab; lhs=true)
+    [K"oldsymbolicgoto" lab] -> vst1_ident(vcx, lab; lhs=true)
     [K"symbolicblock" lab body] ->
         vst1_ident(vcx, lab; lhs=true) & vst1(with(vcx; in_symblock=true), body)
     [K"gc_preserve" x ids...] -> vst1(vcx, x) & all(vst1_ident, vcx, ids)
@@ -1119,6 +1120,7 @@ function _assert_syntaxtree(st::SyntaxTree, parents::Vector{NodeId}, vr)
             [K"label"] -> (:id,)
             [K"symboliclabel"] -> (:name_val,)
             [K"symbolicgoto"] -> (:name_val,)
+            [K"oldsymbolicgoto"] -> (:name_val,)
             [K"Value"] -> (:value,)
             [K"slot"] -> (:var_id,)
             [K"static_parameter"] -> (:var_id,)
@@ -1176,7 +1178,7 @@ vst2(vcx::Validation2Context, st::SyntaxTree) = @stm st begin
     Identifier BindingId Placeholder
     Bool Char Float Float32 BinInt OctInt HexInt Integer
     SourceLocation String Symbol Value core top
-    latestworld latestworld_if_toplevel symbolicgoto symboliclabel TOMBSTONE
+    latestworld latestworld_if_toplevel symbolicgoto oldsymbolicgoto symboliclabel TOMBSTONE
     """ ? pass() : @fail(st, "unrecognized leaf kind")
 
     [K"call" [K"static_eval" cg] xs...] -> get(cg, :name_val, nothing) == "cglobal" ?

JuliaLowering/test/exceptions.jl

@@ -347,4 +347,60 @@ begin
     )
 end
 """) == (1,2)
+
+@testset "goto from try/catch/else with finally" begin
+    # Test that @goto from try block with finally is prevented
+    @test_throws JuliaLowering.LoweringError r"goto from a try/finally block is not permitted" JuliaLowering.include_string(test_mod, """
+    function f()
+        try
+            @goto skip
+        finally
+            println("cleanup")
+        end
+        @label skip
+    end
+    """) broken=true
+
+    # Test that @goto from catch block with finally is prevented
+    @test_throws JuliaLowering.LoweringError r"goto from a catch/finally block is not permitted" JuliaLowering.include_string(test_mod, """
+    function f()
+        try
+            error()
+        catch
+            @goto skip
+        finally
+            println("cleanup")
+        end
+        @label skip
+    end
+    """) broken=true
+
+    # Test that @goto from else block with finally is prevented
+    @test_throws JuliaLowering.LoweringError r"goto from an else/finally block is not permitted" JuliaLowering.include_string(test_mod, """
+    function f()
+        try
+        catch
+        else
+            @goto skip
+        finally
+            println("cleanup")
+        end
+        @label skip
+    end
+    """) broken=true
+
+    # Test that @goto within try/catch/else is allowed when there's no finally
+    @test JuliaLowering.include_string(test_mod, """
+    function f()
+        try
+            @goto skip
+        catch
+        end
+        @label skip
+        return 42
+    end
+    f()
+    """) == 42
+end
+
 end

JuliaSyntax/src/integration/expr.jl

@@ -367,7 +367,12 @@ end
             if kind(secondchildhead) == K"VERSION"
                 # Encode the syntax version into `loc` so that the argument order
                 # matches what ordinary macros expect.
-                loc = Core.MacroSource(loc, popat!(args, 2))
+                # Core.MacroSource was added in Julia 1.13+; fall back to plain loc on older versions.
+                if isdefined(Core, :MacroSource)
+                    loc = Core.MacroSource(loc, popat!(args, 2))
+                else
+                    popat!(args, 2)  # discard the version argument
+                end
             end
         end
         do_lambda = _extract_do_lambda!(args)

JuliaSyntax/src/julia/kinds.jl

@@ -242,6 +242,7 @@ register_kinds!(JuliaSyntax, 0, [
             "abstract"
             "as"
             "doc"
+            "goto"
             "mutable"
             "outer"
             "primitive"