Fix Issue 24135 - Eponymous template member overloads not shown as call candidates (#15572)

compiler/src/dmd/dtemplate.d

@@ -751,6 +751,17 @@ extern (C++) final class TemplateDeclaration : ScopeDsymbol
         return buf.extractChars();
     }
 
+    /****************************
+     * Similar to `toChars`, but does not print the template constraints
+     */
+    const(char)* toCharsNoConstraints() const
+    {
+        HdrGenState hgs = { skipConstraints: true };
+        OutBuffer buf;
+        toCharsMaybeConstraints(this, buf, hgs);
+        return buf.extractChars();
+    }
+
     override Visibility visible() pure nothrow @nogc @safe
     {
         return visibility;

compiler/src/dmd/frontend.h

@@ -1487,6 +1487,7 @@ public:
     bool hasStaticCtorOrDtor() override;
     const char* kind() const override;
     const char* toChars() const override;
+    const char* toCharsNoConstraints() const;
     Visibility visible() override;
     const char* getConstraintEvalError(const char*& tip);
     TemplateDeclaration* isTemplateDeclaration() override;
@@ -3981,6 +3982,7 @@ struct HdrGenState final
     bool doFuncBodies;
     bool vcg_ast;
     bool skipConstraints;
+    bool showOneMember;
     bool fullQual;
     int32_t tpltMember;
     int32_t autoMember;
@@ -3997,6 +3999,7 @@ struct HdrGenState final
         doFuncBodies(),
         vcg_ast(),
         skipConstraints(),
+        showOneMember(true),
         fullQual(),
         tpltMember(),
         autoMember(),
@@ -4007,7 +4010,7 @@ struct HdrGenState final
         inEnumDecl()
     {
     }
-    HdrGenState(bool hdrgen, bool ddoc = false, bool fullDump = false, bool importcHdr = false, bool doFuncBodies = false, bool vcg_ast = false, bool skipConstraints = false, bool fullQual = false, int32_t tpltMember = 0, int32_t autoMember = 0, int32_t forStmtInit = 0, int32_t insideFuncBody = 0, int32_t insideAggregate = 0, bool declstring = false, EnumDeclaration* inEnumDecl = nullptr) :
+    HdrGenState(bool hdrgen, bool ddoc = false, bool fullDump = false, bool importcHdr = false, bool doFuncBodies = false, bool vcg_ast = false, bool skipConstraints = false, bool showOneMember = true, bool fullQual = false, int32_t tpltMember = 0, int32_t autoMember = 0, int32_t forStmtInit = 0, int32_t insideFuncBody = 0, int32_t insideAggregate = 0, bool declstring = false, EnumDeclaration* inEnumDecl = nullptr) :
         hdrgen(hdrgen),
         ddoc(ddoc),
         fullDump(fullDump),
@@ -4015,6 +4018,7 @@ struct HdrGenState final
         doFuncBodies(doFuncBodies),
         vcg_ast(vcg_ast),
         skipConstraints(skipConstraints),
+        showOneMember(showOneMember),
         fullQual(fullQual),
         tpltMember(tpltMember),
         autoMember(autoMember),

compiler/src/dmd/funcsem.d

@@ -1746,10 +1746,24 @@ if (is(Decl == TemplateDeclaration) || is(Decl == FuncDeclaration))
     // max num of overloads to print (-v or -verror-supplements overrides this).
     const uint DisplayLimit = global.params.v.errorSupplementCount();
     const(char)* constraintsTip;
-    // determine if the first candidate was printed
-    int printed;
 
-    bool matchSymbol(Dsymbol s, bool print, bool single_candidate = false)
+    int printed = 0; // number of candidates printed
+    int count = 0; // total candidates
+    bool child; // true if inside an eponymous template
+    const(char)* errorPrefix() @safe
+    {
+        if (child)
+            return "  - Containing: ";
+
+        // align with blank spaces after first message
+        enum plural = "Candidates are: ";
+        enum spaces = "                ";
+        if (printed)
+            return spaces;
+
+        return (count == 1) ? "Candidate is: " : plural;
+    }
+    bool matchSymbol(Dsymbol s, bool print)
     {
         if (auto fd = s.isFuncDeclaration())
         {
@@ -1765,16 +1779,14 @@ if (is(Decl == TemplateDeclaration) || is(Decl == FuncDeclaration))
                 return true;
             auto tf = cast(TypeFunction) fd.type;
             OutBuffer buf;
-            buf.writestring(fd.toPrettyChars());
+            buf.writestring(child ? fd.toChars() : fd.toPrettyChars());
             buf.writestring(parametersTypeToChars(tf.parameterList));
             if (tf.mod)
             {
                 buf.writeByte(' ');
                 buf.MODtoBuffer(tf.mod);
             }
-            .errorSupplemental(fd.loc,
-                printed ? "                `%s`" :
-                single_candidate ? "Candidate is: `%s`" : "Candidates are: `%s`", buf.peekChars());
+            .errorSupplemental(fd.loc, "%s`%s`", errorPrefix(), buf.peekChars());
         }
         else if (auto td = s.isTemplateDeclaration())
         {
@@ -1782,35 +1794,43 @@ if (is(Decl == TemplateDeclaration) || is(Decl == FuncDeclaration))
 
             if (!print)
                 return true;
+
+            // td.onemember may not have overloads set
+            // (see fail_compilation/onemember_overloads.d)
+            // assume if more than one member it is overloaded internally
+            bool recurse = td.onemember && td.members.length > 1;
             OutBuffer buf;
             HdrGenState hgs;
             hgs.skipConstraints = true;
+            hgs.showOneMember = !recurse;
             toCharsMaybeConstraints(td, buf, hgs);
             const tmsg = buf.peekChars();
-            const cmsg = td.getConstraintEvalError(constraintsTip);
-
-            // add blank space if there are multiple candidates
-            // the length of the blank space is `strlen("Candidates are: ")`
+            const cmsg = child ? null : td.getConstraintEvalError(constraintsTip);
 
             if (cmsg)
-            {
-                .errorSupplemental(td.loc,
-                        printed ? "                `%s`\n%s" :
-                        single_candidate ? "Candidate is: `%s`\n%s" : "Candidates are: `%s`\n%s",
-                        tmsg, cmsg);
-            }
+                .errorSupplemental(td.loc, "%s`%s`\n%s", errorPrefix(), tmsg, cmsg);
             else
+                .errorSupplemental(td.loc, "%s`%s`", errorPrefix(), tmsg);
+
+            if (recurse)
             {
-                .errorSupplemental(td.loc,
-                        printed ? "                `%s`" :
-                        single_candidate ? "Candidate is: `%s`" : "Candidates are: `%s`",
-                        tmsg);
+                child = true;
+                foreach (d; *td.members)
+                {
+                    if (d.ident != td.ident)
+                        continue;
+
+                    if (auto fd2 = d.isFuncDeclaration())
+                        matchSymbol(fd2, print);
+                    else if (auto td2 = d.isTemplateDeclaration())
+                        matchSymbol(td2, print);
+                }
+                child = false;
             }
         }
         return true;
     }
     // determine if there's > 1 candidate
-    int count = 0;
     overloadApply(declaration, (s) {
         if (matchSymbol(s, false))
             count++;
@@ -1820,7 +1840,7 @@ if (is(Decl == TemplateDeclaration) || is(Decl == FuncDeclaration))
     overloadApply(declaration, (s) {
         if (global.params.v.verbose || printed < DisplayLimit)
         {
-            if (matchSymbol(s, true, count == 1))
+            if (matchSymbol(s, true))
                 printed++;
         }
         else

compiler/src/dmd/hdrgen.d

@@ -62,6 +62,7 @@ struct HdrGenState
     bool doFuncBodies;  /// include function bodies in output
     bool vcg_ast;       /// write out codegen-ast
     bool skipConstraints;  // skip constraints when doing templates
+    bool showOneMember = true;
 
     bool fullQual;      /// fully qualify types when printing
     int tpltMember;
@@ -1974,7 +1975,7 @@ void toCharsMaybeConstraints(const TemplateDeclaration td, ref OutBuffer buf, re
     }
     buf.writeByte(')');
 
-    if (td.onemember)
+    if (hgs.showOneMember && td.onemember)
     {
         if (const fd = td.onemember.isFuncDeclaration())
         {

compiler/test/fail_compilation/onemember_overloads.d

@@ -0,0 +1,38 @@
+/*
+TEST_OUTPUT:
+---
+fail_compilation/onemember_overloads.d(29): Error: none of the overloads of `skipOver` are callable using argument types `()`
+fail_compilation/onemember_overloads.d(25):        Candidates are: `onemember_overloads.skipOver(string)`
+fail_compilation/onemember_overloads.d(18):                        `skipOver(alias pred = (a, b) => a == b)`
+fail_compilation/onemember_overloads.d(20):          - Containing: `skipOver(Haystack, Needles...)(ref Haystack haystack, Needles needles)`
+fail_compilation/onemember_overloads.d(21):          - Containing: `skipOver(R)(ref R r1)`
+fail_compilation/onemember_overloads.d(22):          - Containing: `skipOver(R, Es...)(ref R r, Es es)`
+fail_compilation/onemember_overloads.d(30): Error: template `t2` is not callable using argument types `!()()`
+fail_compilation/onemember_overloads.d(33):        Candidate is: `t2(T)`
+fail_compilation/onemember_overloads.d(35):          - Containing: `t2(string)`
+fail_compilation/onemember_overloads.d(36):          - Containing: `t2(int[])`
+fail_compilation/onemember_overloads.d(37):          - Containing: `t2(R)(R)`
+---
+*/
+
+template skipOver(alias pred = (a, b) => a == b)
+{
+    bool skipOver(Haystack, Needles...)(ref Haystack haystack, Needles needles) => true;
+    bool skipOver(R)(ref R r1) => true;
+    bool skipOver(R, Es...)(ref R r, Es es) => true;
+}
+
+void skipOver(string);
+
+void main()
+{
+    skipOver();
+    t2();
+}
+
+template t2(T)
+{
+    bool t2(string);
+    bool t2(int[]);
+    bool t2(R)(R);
+}