fix(pgfmath): Strip spaces around each function arg pgf-tikz#1123

Signed-off-by: muzimuzhi <muzimuzhi@gmail.com>

doc/generic/pgf/CHANGELOG.md

@@ -57,7 +57,9 @@ lot of contributed changes. Thanks to everyone who volunteered their time!
 - Update Debian installation instructions
 - Suppress white space at line end when `datavisualization` reads from a file 
   #1112
-- Form-only patterns have no specified color #1122 
+- Form-only patterns have no specified color #1122
+- Functions defined by `/pgf/declare function` now allow spaces in their arg 
+  list #1123
 
 ### Changed
 

tex/generic/pgf/math/pgfmathfunctions.code.tex

@@ -184,7 +184,7 @@
             \expandafter\pgfmath@toks\expandafter=\expandafter{\pgfmath@local@body}%
         \else%
             \pgfmath@toks={}%
-            \expandafter\pgfmath@local@function@@body\pgfmath@local@args,,%
+            \expandafter\pgfmath@local@function@@body@trimspaces\pgfmath@local@args,,%
         \fi%
         \xdef\pgfmath@local@temp{%
             \noexpand\pgfmathnotifynewdeclarefunction{\pgfmath@local@name}{\the\c@pgf@counta}%
@@ -202,7 +202,13 @@
     \pgfmathdeclarefunction{#1}{#2}{\pgfmathparse{#3}}%
 }%
 
-\def\pgfmath@local@function@@body#1,{%
+\def\pgfmath@local@function@@body@trimspaces#1,{%
+  % strip spaces on both sides of #1 in case it starts with a space,
+  % e.g., #1 is ` \y` which comes from `func(\x, \y)=...;`
+  \expandafter\pgfmath@local@function@@body\expanded{{\pgfutil@trimspaces@noexp{#1}}}%
+}
+
+\def\pgfmath@local@function@@body#1{%
     \def\pgfmath@local@test{#1}%
     \ifx\pgfmath@local@test\pgfutil@empty%
         \let\pgfmath@local@next=\relax%
@@ -215,7 +221,7 @@
         \pgfmath@toks={}%
         \expandafter\pgfmath@local@function@@@body\pgfmath@local@body @%
         \edef\pgfmath@local@body{\the\pgfmath@toks}%
-        \let\pgfmath@local@next=\pgfmath@local@function@@body%
+        \let\pgfmath@local@next=\pgfmath@local@function@@body@trimspaces%
     \fi%
     \pgfmath@local@next%
 }

tex/generic/pgf/utilities/pgfutil-common.tex

@@ -49,6 +49,15 @@
 \def\pgfutil@trimspaces@@#1Q#2{#1}
 \catcode`\Q=11
 
+% \pgfutil@trimspaces@noexp{<token list>}
+%
+% Variant of \pgfutil@trimspaces that after full expansion leaves stripped
+% original text unexpanded in the input stream. Same as \trim@spaces@noexp
+% in trimspaces.sty
+\def\pgfutil@trimspaces@noexp#1{%
+  \unexpanded\expandafter\expandafter\expandafter{\pgfutil@trimspaces{#1}}%
+}
+
 % \pgfutil@ifx{<token 1>}{<token 2>}{<true code>}{<false code>}
 %
 % This macro is expandable.