Fix dockerfile parsing issue (#7224)

Author: sambsnyd

rewrite-docker/src/main/antlr/DockerLexer.g4

@@ -88,7 +88,14 @@ EQUALS     : '=' { if (!afterHealthcheck) atLineStart = false; };
 // Flag with optional value: --name or --name=value
 // Captures the entire flag as a single token, stopping at whitespace
 // This avoids the greedy flagValue+ parsing issue while keeping shell commands working
-FLAG : '--' [a-zA-Z] [a-zA-Z0-9_-]* ('=' ~[ \t\r\n]+)? { if (!afterHealthcheck) atLineStart = false; };
+// Flag values can contain quoted strings (which may include spaces)
+FLAG : '--' [a-zA-Z] [a-zA-Z0-9_-]* ('=' FLAG_VALUE_PART+)? { if (!afterHealthcheck) atLineStart = false; };
+fragment FLAG_VALUE_PART
+    : '"' ( '\\' ~[\r\n] | ~["\\\r\n] )* '"'   // Double-quoted string (with escapes)
+    | '\'' ~['\r\n]* '\''                        // Single-quoted string (literal)
+    | ~[ \t\r\n"'\\]                             // Unquoted character
+    | '\\' ~[\r\n]                               // Escaped character
+    ;
 
 // Standalone -- (double dash without flag name) - used in shell commands
 DASH_DASH  : '--' { if (!afterHealthcheck) atLineStart = false; };
@@ -134,6 +141,10 @@ fragment COMMAND_SUBST_INNER : COMMAND_SUBST | ~[()];
 // Content cannot span newlines (backtick command substitution doesn't support that)
 BACKTICK_SUBST : '`' ~[ \t\r\n`] ~[`\r\n]* '`' { atLineStart = false; };
 
+// Lone dollar sign that doesn't match ENV_VAR, SPECIAL_VAR, or COMMAND_SUBST
+// This handles cases like $'hello' (bash ANSI-C quoting) where $ precedes a quote
+DOLLAR : '$' { atLineStart = false; };
+
 // Unquoted text (arguments, file paths, etc.)
 // This should be after more specific tokens
 // Note: comma is NOT excluded here - it's only special in JSON arrays

rewrite-docker/src/main/antlr/DockerParser.g4

@@ -169,6 +169,7 @@ shellFormTextElement
     | COMMAND_SUBST      // Allow $(command) in shell commands
     | BACKTICK_SUBST     // Allow `command` in shell commands
     | SPECIAL_VAR        // Allow $!, $$, $?, etc. in shell commands
+    | DOLLAR             // Allow lone $ in shell commands (e.g., $'hello' ANSI-C quoting)
     | EQUALS
     | FLAG               // Allow --option or --option=value in shell commands
     | DASH_DASH
@@ -200,6 +201,7 @@ preambleElement
     | COMMAND_SUBST
     | BACKTICK_SUBST
     | SPECIAL_VAR
+    | DOLLAR
     | EQUALS
     | FLAG
     | DASH_DASH
@@ -273,6 +275,7 @@ labelOldValueElement
     | COMMAND_SUBST
     | BACKTICK_SUBST
     | SPECIAL_VAR
+    | DOLLAR
     | EQUALS
     | FLAG
     | DASH_DASH
@@ -327,6 +330,7 @@ envTextElementEquals
     | COMMAND_SUBST
     | BACKTICK_SUBST
     | SPECIAL_VAR
+    | DOLLAR
     // NOTE: EQUALS is explicitly NOT included to allow multiple KEY=value pairs
     ;
 
@@ -410,6 +414,7 @@ textElement
     | COMMAND_SUBST   // Allow $(command) in text
     | BACKTICK_SUBST  // Allow `command` in text
     | SPECIAL_VAR     // Allow $!, $$, $?, etc. in text
+    | DOLLAR          // Allow lone $ in text (e.g., $'hello' ANSI-C quoting)
     | EQUALS     // Allow = in shell form text (e.g., ENV_VAR=value in RUN commands)
     | FLAG       // Allow --option or --option=value in text
     | DASH_DASH  // Allow -- in shell form text (e.g., --option in shell commands)