[osh] Promote a string to an array with str+=(...) (#2283)

* [osh/cmd_eval] Disallow string promotion with +=() with strict_array
* [osh/cmd_eval] Use tagswitch

Author: akinomyoga

builtin/assign_osh.py

@@ -20,7 +20,7 @@
 from display import ui
 from frontend import flag_util
 from frontend import args
-from mycpp.mylib import log
+from mycpp.mylib import log, tagswitch
 from osh import cmd_eval
 from osh import sh_expr_eval
 from data_lang import j8_lite
@@ -242,20 +242,36 @@ def _AssignVarForBuiltin(mem, rval, pair, which_scopes, flags, arith_ev,
                     "Can't convert type %s into BashArray" %
                     ui.ValType(old_val), pair.blame_word)
         elif flag_A:
-            if old_val.tag() in (value_e.Undef, value_e.Str):
-                # Note: We explicitly initialize BashAssoc for Undef.
-                val = bash_impl.BashAssoc_New()
-            elif old_val.tag() == value_e.BashAssoc:
-                # We do not need adjustments for -A.
-                pass
-            else:
-                # Note: BashArray cannot be converted to a BashAssoc
-                e_die(
-                    "Can't convert type %s into BashAssoc" %
-                    ui.ValType(old_val), pair.blame_word)
+            with tagswitch(old_val) as case:
+                if case(value_e.Undef):
+                    # Note: We explicitly initialize BashAssoc for Undef.
+                    val = bash_impl.BashAssoc_New()
+                elif case(value_e.Str):
+                    # Note: We explicitly initialize BashAssoc for Str.  When
+                    #   applying +=() to Str, we associate an old value to the
+                    #   key '0'.  OSH disables this when strict_array is turned
+                    #   on.
+                    assoc_val = bash_impl.BashAssoc_New()
+                    if pair.plus_eq:
+                        if mem.exec_opts.strict_array():
+                            e_die(
+                                "Can't convert Str to BashAssoc (strict_array)",
+                                pair.blame_word)
+                        bash_impl.BashAssoc_SetElement(
+                            assoc_val, '0',
+                            cast(value.Str, old_val).s)
+                    val = assoc_val
+                elif case(value_e.BashAssoc):
+                    # We do not need adjustments for -A.
+                    pass
+                else:
+                    # Note: BashArray cannot be converted to a BashAssoc
+                    e_die(
+                        "Can't convert type %s into BashAssoc" %
+                        ui.ValType(old_val), pair.blame_word)
 
         val = cmd_eval.ListInitializeTarget(val, initializer, pair.plus_eq,
-                                            pair.blame_word)
+                                            mem.exec_opts, pair.blame_word)
     elif pair.plus_eq:
         old_val = sh_expr_eval.OldValue(
             lval,

doc/ref/chap-osh-assign.md

@@ -81,9 +81,7 @@ In the first phase, the type adjustment is performed in the following way:
   element, where the original value is stored at index `0`.  If the assignment
   is performed through an assignment builtin and flag `-A` is supplied to the
   builtin, the assignment creates a BashAssoc with one element, where the
-  original value is stored at key `"0"`, instead of a BashArray.  If the
-  assignment operator is `+=`, OSH issues an error "Can't append an array to
-  string", while Bash is permissive.
+  original value is stored at key `"0"`, instead of a BashArray.
 - When the LHS is an indexed or associative arrays, the original array is
   directly used for the modification target.  If the
   assignment is performed through an assignment builtin and mismatching flag
@@ -121,17 +119,17 @@ These rules are summarized in the following table.
   - Str
   - (none)
   - BashArray with one element, with the original string at index 0
-  - OSH does not accept `+=`, so the element is never used
+  - Error with `strict_array`
 - tr
   - <!-- empty -->
   - `-a`
   - BashArray with one element, with the original string at index 0
-  - OSH does not accept `+=`, so the element is never used
+  - Error with `strict_array`
 - tr
   - <!-- empty -->
   - `-A`
   - BashAssoc with one element, with the original string at key `"0"`
-  - OSH does not accept `+=`, so the element is never used
+  - Error with `strict_array`
 - tr
   - BashArray
   - (none)

osh/cmd_eval.py

@@ -193,18 +193,23 @@ def _HasManyStatuses(node):
 def ListInitializeTarget(old_val,
                          initializer,
                          has_plus,
+                         exec_opts,
                          blame_loc,
                          destructive=True):
-    # type: (value_t, value.InitializerList, bool, loc_t, bool) -> value_t
+    # type: (value_t, value.InitializerList, bool, optview.Exec, loc_t, bool) -> value_t
     UP_old_val = old_val
     with tagswitch(old_val) as case:
         if case(value_e.Undef):
             return bash_impl.BashArray_New()
         elif case(value_e.Str):
             if has_plus:
-                e_die("Can't append array to string")
-
-            return bash_impl.BashArray_New()
+                if exec_opts.strict_array():
+                    e_die("Can't convert Str to BashArray (strict_array)",
+                          blame_loc)
+                old_val = cast(value.Str, UP_old_val)
+                return bash_impl.BashArray_FromList([old_val.s])
+            else:
+                return bash_impl.BashArray_New()
         elif case(value_e.BashArray):
             old_val = cast(value.BashArray, UP_old_val)
             if not destructive:
@@ -624,6 +629,7 @@ def _EvalTempEnv(self, more_env, flags):
                 val = ListInitializeTarget(old_val,
                                            initializer,
                                            has_plus,
+                                           self.exec_opts,
                                            e_pair.left,
                                            destructive=False)
 
@@ -1040,7 +1046,7 @@ def _DoShAssignment(self, node, cmd_st):
                                                 node.left)
 
                 val = ListInitializeTarget(old_val, initializer, has_plus,
-                                           pair.left)
+                                           self.exec_opts, pair.left)
 
             elif has_plus:
                 # do not respect set -u

spec/append.test.sh

@@ -48,13 +48,11 @@ argv.py "${y[@]}"
 #### error: s+=(my array)
 s='abc'
 s+=(d e f)
-echo $s
-## status: 1
-## stdout-json: ""
-## BUG bash/mksh status: 0
-## BUG bash/mksh stdout: abc
-## OK zsh status: 0
-## OK zsh stdout: abc d e f
+argv.py "${s[@]}"
+## status: 0
+## STDOUT:
+['abc', 'd', 'e', 'f']
+## END
 
 #### error: myarray+=s
 
@@ -78,16 +76,16 @@ typeset s+=(d e f)
 echo status=$?
 argv.py "${s[@]}"
 
-## status: 1
+## status: 0
 ## STDOUT:
 abc
-## END
-## OK bash status: 0
-## OK bash STDOUT:
-abc
 status=0
 ['abc', 'd', 'e', 'f']
 ## END
+## N-I mksh/zsh status: 1
+## N-I mksh/zsh stdout: abc
+## N-I mksh stderr: mksh: <stdin>[4]: syntax error: '(' unexpected
+## N-I zsh stderr: typeset: not valid in this context: s+
 
 #### error: typeset myarray+=s
 typeset a=(x y)

spec/array-literal.test.sh

@@ -57,3 +57,57 @@ status=1
 status=1
 ['x', 'y', 'z']
 ## END
+
+#### s+=() with strict_array
+case $SH in bash) ;; *) shopt --set strict_array;; esac
+
+s1=hello
+s2=world
+
+# Overwriting Str with a new BashArray is allowed
+eval 's1=(1 2 3 4)'
+echo status=$?
+declare -p s1
+# Promoting Str to a BashArray is disallowed
+eval 's2+=(1 2 3 4)'
+echo status=$?
+declare -p s2
+## STDOUT:
+status=0
+declare -a s1=(1 2 3 4)
+status=1
+declare -- s2=world
+## END
+## N-I bash STDOUT:
+status=0
+declare -a s1=([0]="1" [1]="2" [2]="3" [3]="4")
+status=0
+declare -a s2=([0]="world" [1]="1" [2]="2" [3]="3" [4]="4")
+## END
+
+#### declare -A s+=() with strict_array
+case $SH in bash) ;; *) shopt --set strict_array;; esac
+
+s1=hello
+s2=world
+
+# Overwriting Str with a new BashAssoc is allowed
+eval 'declare -A s1=([a]=x [b]=y)'
+echo status=$?
+declare -p s1
+# Promoting Str to a BashAssoc is disallowed
+eval 'declare -A s2+=([a]=x [b]=y)'
+echo status=$?
+declare -p s2
+## STDOUT:
+status=0
+declare -A s1=(['a']=x ['b']=y)
+status=1
+declare -- s2=world
+## END
+## N-I bash STDOUT:
+status=0
+declare -A s1=([b]="y" [a]="x" )
+status=0
+declare -A s2=([0]="world" [b]="y" [a]="x" )
+## END