[perl #80368] Fix implicit assignop in qq"a\U="

The bug report explains it all:
> $ perl -e 'print "a\U="'
> Can't modify constant item in concatenation (.) or string at -e line 1, near "print "a\U=""
> Execution of -e aborted due to compilation errors.
>
> The "a\U=" string constant ought to generate ops corresponding roughly to
> "a".uc("=") (which would then be constant-folded).  However, the "=" is
> being interpreted by the tokeniser as part of the concatenation operator,
> producing ops corresponding to "a".=uc("") (which generates the error).
>
> This happens because the implicit concatenation operator is generated
> in toke.c via the Aop() macro, which allows an addition-type operator
> to be mutated into an assignment operator if it is immediately followed
> by an "=".  It should instead be generated via one of the other macros,
> or possibly a new macro, that doesn't allow for mutation to an assignment
> operator.

This commit does the latter.

> There are multiple sites in toke.c making the same mistake.

The other two instances are harmless, but the next commit will change
them for a different reason (avoiding unnecessary PL_expect assign-
ments with a view to eventually removing PL_lex_expect).

diff --git a/t/base/lex.t b/t/base/lex.t
index 01ab208..d75fa57 100644 (file)
--- a/t/base/lex.t
+++ b/t/base/lex.t
@@ -1,6 +1,6 @@
 #!./perl
 
-print "1..91\n";
+print "1..92\n";
 
 $x = 'x';
 
@@ -434,3 +434,7 @@ print "ok $test - y <comment> <newline> ...\n"; $test++;
 print "not " unless (time
                      =>) eq time=>;
 print "ok $test - => quotes keywords across lines\n"; $test++;
+
+# [perl #80368]
+print "not " unless eval '"a\U="' eq "a=";
+print "ok $test - [perl #80368] qq <a\\U=>\n"; $test++;

diff --git a/toke.c b/toke.c
index 68cf152..a7ba403 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -196,6 +196,7 @@ static const char* const lex_state_names[] = {
  * PWop         : power operator
  * PMop         : pattern-matching operator
  * Aop          : addition-level operator
+ * AopNOASSIGN  : addition-level operator that is never part of .=
  * Mop          : multiplication-level operator
  * Eop          : equality-testing operator
  * Rop          : relational operator <= != gt
@@ -232,6 +233,7 @@ static const char* const lex_state_names[] = {
 #define PWop(f)  return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)POWOP)))
 #define PMop(f)  return(pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MATCHOP))
 #define Aop(f)   return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)ADDOP)))
+#define AopNOASSIGN(f) return (pl_yylval.ival=f, PL_bufptr=s, REPORT((int)ADDOP))
 #define Mop(f)   return ao((pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)MULOP)))
 #define Eop(f)   return (pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)EQOP))
 #define Rop(f)   return (pl_yylval.ival=f, PL_expect=XTERM, PL_bufptr=s, REPORT((int)RELOP))
@@ -4390,7 +4392,7 @@ Perl_yylex(pTHX)
                if (PL_lex_casemods == 1 && PL_lex_inpat)
                    OPERATOR(',');
                else
-                   Aop(OP_CONCAT);
+                   AopNOASSIGN(OP_CONCAT);
            }
            else
                return yylex();