syntax: Disallow using @goto to skip finally blocks

Add syntax errors when `@goto` is used to jump out of try, catch, or else blocks when a finally block is present.

Fixes #60972

Co-Authored-By: Claude <noreply@anthropic.com>

Author: IanButterworth

JuliaLowering/src/desugaring.jl

@@ -2120,6 +2120,7 @@ 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/test/exceptions.jl

@@ -352,4 +352,59 @@ 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

base/essentials.jl

@@ -991,6 +991,9 @@ end
 
 `@label` and `@goto` cannot create jumps to different top-level statements. Attempts cause an
 error. To still use `@goto`, enclose the `@label` and `@goto` in a block.
+
+Also, `@goto` is not allowed for jumping out of a `try`, `catch`, or `else` block when a `finally`
+block is present.
 """
 macro goto(name::Symbol)
     return esc(Expr(:symbolicgoto, name))

src/julia-syntax.scm

@@ -1433,6 +1433,12 @@
     (cond ((and (length> e 4) (not (equal? (caddddr e) '(false))))
            (if (has-unmatched-symbolic-goto? tryb)
                (error "goto from a try/finally block is not permitted"))
+           (if (and (not (equal? catchb '(false)))
+                    (has-unmatched-symbolic-goto? catchb))
+               (error "goto from a catch/finally block is not permitted"))
+           (if (and (length> e 5)
+                    (has-unmatched-symbolic-goto? (cons 'block (cdddddr e))))
+               (error "goto from an else/finally block is not permitted"))
            (let ((finalb (caddddr e)))
              (expand-forms
               `(tryfinally

test/exceptions.jl

@@ -131,16 +131,6 @@ end
         @goto outofcatch
     end
     @label outofcatch
-    try
-        error("A")
-    catch
-        @test length(current_exceptions()) == 1
-        @goto outofcatch2
-    finally
-        @test length(current_exceptions()) == 0
-    end
-    @label outofcatch2
-    @test length(current_exceptions()) == 0
 
     # Exiting from a try block in various ways should not affect the exception
     # stack state.

test/goto.jl

@@ -99,6 +99,34 @@ end
         end
     end)
 
+@test Expr(:error, "goto from a catch/finally block is not permitted around $(@__FILE__):$(3 + @__LINE__)") ==
+    Meta.lower(@__MODULE__, quote
+        function goto_test6_catch()
+            try
+                error()
+            catch
+                @goto a
+            finally
+            end
+            @label a
+            return
+        end
+    end)
+
+@test Expr(:error, "goto from an else/finally block is not permitted around $(@__FILE__):$(3 + @__LINE__)") ==
+    Meta.lower(@__MODULE__, quote
+        function goto_test6_else()
+            try
+            catch
+            else
+                @goto a
+            finally
+            end
+            @label a
+            return
+        end
+    end)
+
 
 function goto_test6()
     @goto a