Issue #9232: Support trailing commas in function declarations.

For example, "def f(*, a = 3,): pass" is now legal.

Patch from Mark Dickinson.

2 files changed, 74 insertions, 55 deletions

diff --git a/Python/ast.c b/Python/ast.c
index b572088..c1c3907 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -1260,16 +1260,20 @@ ast_for_arguments(struct compiling *c, const node *n)
        and varargslist (lambda definition).
 
        parameters: '(' [typedargslist] ')'
-       typedargslist: ((tfpdef ['=' test] ',')*
-           ('*' [tfpdef] (',' tfpdef ['=' test])* [',' '**' tfpdef]
-           | '**' tfpdef)
-           | tfpdef ['=' test] (',' tfpdef ['=' test])* [','])
+       typedargslist: (tfpdef ['=' test] (',' tfpdef ['=' test])* [',' [
+               '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
+             | '**' tfpdef [',']]]
+         | '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
+         | '**' tfpdef [','])
        tfpdef: NAME [':' test]
-       varargslist: ((vfpdef ['=' test] ',')*
-           ('*' [vfpdef] (',' vfpdef ['=' test])*  [',' '**' vfpdef]
-           | '**' vfpdef)
-           | vfpdef ['=' test] (',' vfpdef ['=' test])* [','])
+       varargslist: (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
+               '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
+             | '**' vfpdef [',']]]
+         | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
+         | '**' vfpdef [',']
+       )
        vfpdef: NAME
+
     */
     int i, j, k, nposargs = 0, nkwonlyargs = 0;
     int nposdefaults = 0, found_default = 0;
@@ -1371,7 +1375,8 @@ ast_for_arguments(struct compiling *c, const node *n)
                 i += 2; /* the name and the comma */
                 break;
             case STAR:
-                if (i+1 >= NCH(n)) {
+                if (i+1 >= NCH(n) ||
+                    (i+2 == NCH(n) && TYPE(CHILD(n, i+1)) == COMMA)) {
                     ast_error(c, CHILD(n, i),
                         "named arguments must follow bare *");
                     return NULL;
diff --git a/Python/graminit.c b/Python/graminit.c
index 8212b2a..354dc12 100644
--- a/Python/graminit.c
+++ b/Python/graminit.c
@@ -204,11 +204,13 @@ static arc arcs_9_6[2] = {
     {32, 7},
     {0, 6},
 };
-static arc arcs_9_7[2] = {
+static arc arcs_9_7[3] = {
     {30, 12},
     {34, 3},
+    {0, 7},
 };
-static arc arcs_9_8[1] = {
+static arc arcs_9_8[2] = {
+    {32, 13},
     {0, 8},
 };
 static arc arcs_9_9[2] = {
@@ -221,35 +223,39 @@ static arc arcs_9_10[3] = {
     {0, 10},
 };
 static arc arcs_9_11[3] = {
-    {30, 13},
-    {32, 14},
+    {30, 14},
+    {32, 15},
     {0, 11},
 };
 static arc arcs_9_12[3] = {
     {32, 7},
-    {31, 15},
+    {31, 16},
     {0, 12},
 };
-static arc arcs_9_13[2] = {
-    {32, 14},
+static arc arcs_9_13[1] = {
     {0, 13},
 };
 static arc arcs_9_14[2] = {
-    {30, 16},
+    {32, 15},
+    {0, 14},
+};
+static arc arcs_9_15[3] = {
+    {30, 17},
     {34, 3},
+    {0, 15},
 };
-static arc arcs_9_15[1] = {
+static arc arcs_9_16[1] = {
     {26, 6},
 };
-static arc arcs_9_16[3] = {
-    {32, 14},
-    {31, 17},
-    {0, 16},
+static arc arcs_9_17[3] = {
+    {32, 15},
+    {31, 18},
+    {0, 17},
 };
-static arc arcs_9_17[1] = {
-    {26, 13},
+static arc arcs_9_18[1] = {
+    {26, 14},
 };
-static state states_9[18] = {
+static state states_9[19] = {
     {3, arcs_9_0},
     {3, arcs_9_1},
     {3, arcs_9_2},
@@ -257,17 +263,18 @@ static state states_9[18] = {
     {1, arcs_9_4},
     {4, arcs_9_5},
     {2, arcs_9_6},
-    {2, arcs_9_7},
-    {1, arcs_9_8},
+    {3, arcs_9_7},
+    {2, arcs_9_8},
     {2, arcs_9_9},
     {3, arcs_9_10},
     {3, arcs_9_11},
     {3, arcs_9_12},
-    {2, arcs_9_13},
+    {1, arcs_9_13},
     {2, arcs_9_14},
-    {1, arcs_9_15},
-    {3, arcs_9_16},
-    {1, arcs_9_17},
+    {3, arcs_9_15},
+    {1, arcs_9_16},
+    {3, arcs_9_17},
+    {1, arcs_9_18},
 };
 static arc arcs_10_0[1] = {
     {23, 1},
@@ -319,11 +326,13 @@ static arc arcs_11_6[2] = {
     {32, 7},
     {0, 6},
 };
-static arc arcs_11_7[2] = {
+static arc arcs_11_7[3] = {
     {36, 12},
     {34, 3},
+    {0, 7},
 };
-static arc arcs_11_8[1] = {
+static arc arcs_11_8[2] = {
+    {32, 13},
     {0, 8},
 };
 static arc arcs_11_9[2] = {
@@ -336,35 +345,39 @@ static arc arcs_11_10[3] = {
     {0, 10},
 };
 static arc arcs_11_11[3] = {
-    {36, 13},
-    {32, 14},
+    {36, 14},
+    {32, 15},
     {0, 11},
 };
 static arc arcs_11_12[3] = {
     {32, 7},
-    {31, 15},
+    {31, 16},
     {0, 12},
 };
-static arc arcs_11_13[2] = {
-    {32, 14},
+static arc arcs_11_13[1] = {
     {0, 13},
 };
 static arc arcs_11_14[2] = {
-    {36, 16},
+    {32, 15},
+    {0, 14},
+};
+static arc arcs_11_15[3] = {
+    {36, 17},
     {34, 3},
+    {0, 15},
 };
-static arc arcs_11_15[1] = {
+static arc arcs_11_16[1] = {
     {26, 6},
 };
-static arc arcs_11_16[3] = {
-    {32, 14},
-    {31, 17},
-    {0, 16},
+static arc arcs_11_17[3] = {
+    {32, 15},
+    {31, 18},
+    {0, 17},
 };
-static arc arcs_11_17[1] = {
-    {26, 13},
+static arc arcs_11_18[1] = {
+    {26, 14},
 };
-static state states_11[18] = {
+static state states_11[19] = {
     {3, arcs_11_0},
     {3, arcs_11_1},
     {3, arcs_11_2},
@@ -372,17 +385,18 @@ static state states_11[18] = {
     {1, arcs_11_4},
     {4, arcs_11_5},
     {2, arcs_11_6},
-    {2, arcs_11_7},
-    {1, arcs_11_8},
+    {3, arcs_11_7},
+    {2, arcs_11_8},
     {2, arcs_11_9},
     {3, arcs_11_10},
     {3, arcs_11_11},
     {3, arcs_11_12},
-    {2, arcs_11_13},
+    {1, arcs_11_13},
     {2, arcs_11_14},
-    {1, arcs_11_15},
-    {3, arcs_11_16},
-    {1, arcs_11_17},
+    {3, arcs_11_15},
+    {1, arcs_11_16},
+    {3, arcs_11_17},
+    {1, arcs_11_18},
 };
 static arc arcs_12_0[1] = {
     {23, 1},
@@ -1879,11 +1893,11 @@ static dfa dfas[85] = {
      "\000\000\100\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
     {264, "parameters", 0, 4, states_8,
      "\000\040\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
-    {265, "typedargslist", 0, 18, states_9,
+    {265, "typedargslist", 0, 19, states_9,
      "\000\000\200\000\006\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
     {266, "tfpdef", 0, 4, states_10,
      "\000\000\200\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
-    {267, "varargslist", 0, 18, states_11,
+    {267, "varargslist", 0, 19, states_11,
      "\000\000\200\000\006\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},
     {268, "vfpdef", 0, 2, states_12,
      "\000\000\200\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"},